Search

Recently, pipelines have replaced more carbon-intensive transportation methods making them more environmentally friendly for transporting energy and water supplies. However, pipelines can pollute the air, water, soil, and climate when they leak, causing economic, and environmental damage. Pipeline online monitoring provides data analysis and suitable controlling strategies to contain the risk. This paper proposes a three-dimensional numerical model simulation taking advantage of the fluids moving through pipelines at specific speeds. The transport speeds depend on many conditions, such as pipe diameter, the pressure through which the fluid is being transported, and other factors, such as terrain's topography and viscosity of the fluid. Under these conditions, the inspection approach uses a self-charging movable ball. The sensors inside the ball capture data as it travels through the pipe. The simulation focuses on spherical flow and pipe noise with and without leakage based on the COMSOL software platform. The paper shows the effect of several parameters, including leak location, sensor placement, ball diameter, sound pressure level propagation along a pipe and around the sphere, velocity, and temperature distribution that give the background for future smart ball design in a promising practical pipeline test project.

The membrane gas separation process has gained significant attention using the computational fluid dynamics (CFD) technique. This study considered the CFD method to find gas concentration profiles in a hollow fiber membrane (HFM) module to separate the binary gas mixture. The membrane was considered with a fiber thickness where each component’s mass fluxes could be obtained based on the local partial pressures, solubility, diffusion, and the membrane’s selectivity. COMSOL Multiphysics was used to solve the numerical solution at corresponding operating conditions and results were compared to experimental data. The two different mixtures, CO2/CH4 and N2/O2, were investigated to obtain concentration gradient and mass flux profiles of CO2 and O2 species in an axial direction. This study allows assessing the feed pressure’s impact on the HFM system’s overall performance. These results demonstrate that the increment in feed pressures decreased the membrane system’s separation performance. The impact of hollow fiber length indicates that increasing the active fiber length has a higher effective mass transfer region but dilutes the permeate-side purities of O2 (46% to 28%) and CO2 (93% to 73%). The results show that increasing inlet pressure and a higher concentration gradient resulted in higher flux through the membrane.

This article deals with the numerical simulation of a two-dimensional instantaneous heat and mass transfer processes within a commonly used intermetallic compound (a.k.a. Mischmetal) packed in a unit disc of an annulus-disc reactors, during hydrogen gas desorption. Using the finite volumes technique bundled in the OpenFOAM® CFD code, temperature and amount of desorbed hydrogen and their time-averaged quantities inside the metal-hydride packed bed are obtained for various temperatures of fluids used in heat transfer, and several outlet pressure magnitudes. Using a set of numerical simulations, we have emphasized the impacts of both parameters on metal-hydride reactor performance related to discharging time. An excellent accord was recorded for the present simulations results compared against the literature-reported experimental data [20].

This paper presents a method for evaluating the risk of autoignition for the canonical problem of an enclosed hydrogen jet in crossflow (JICF), which is highly relevant to the design of mixing ducts. The proposed method is based on the separation of the underlying mixing pattern from the evolution of the chemical reactions, whereas the effect of mixing is maintained on the latter with the purpose of creating a reliable yet computationally efficient design tool for hydrogen gas turbines. Two variants of the incompletely stirred reactor network (ISRN) approach are proposed that provide the evolution of preignition radicals and autoignition kernel location, leveraging a nonreacting computational fluid dynamics solution or an analytical mixing pattern. The ISRN governing equations include all the salient features of hydrogen transport and lead to a conservative estimate of autoignition risk. Application to a few model problems with varied operating conditions suggests that radical buildup in the JICF can lead to autoignition in the vicinity of a most reactive mixture fraction, which is consistent with other laminar or turbulent hydrogen flows. However, the radical formation and autoignition kernel location strongly depend on the prediction of the underlying mixing field and the amount of differential diffusion within the JICF, which here primarily favors lower values of the composite mixture fraction and the transport of hydrogen and radicals away from the jet trajectory.

The formulation of the CFD-DEM model, CD-MELT, is established in this study to include three-phase non-isothermal processes with simultaneous combustion and melting for gasification simulations. To demonstrate the model capability, CD-MELT is used to assess the need for slag recycling for the non-isothermal melting of municipal solid wastes (MSW) in a prototype waste-to-energy research facility. The simulation encompasses the full fixed-bed slagging gasification process, including chemical reactions and melting of MSW and slag. In order to assess the need for slag recycling, comparisons are made for the two cases of with and without, in terms of the slag mass, liquid slag volume fraction, exit gas composition, and temperature distribution in the gasifier. The prediction results enable the tracking of liquid molten slag as it permeates through the solids-packed bed for the first time in the literature as far as we are aware, which is crucial to address design considerations such as distribution of bed temperature and optimal location for slag-tap holes at the bottom, as well as potential slag clogging within the porous media. The model also predicts an uneven and intermittent slag permeation through the packed bed without the recycling, and provides a plausible explanation for the operators’ experience of why slag recycling is important for process stability. Finally, the predicted slag outlet temperature using the proposed CFD approach also agrees well with the measurement data published in an earlier case study for the same facility.

In the present paper, a new strategy of multigrid method is introduced to accelerate the convergence speed of numerical simulations via lattice Boltzmann method. Based on the popular V-cycle multigrid algorithm, a simplified multigrid algorithm is presented and validated through the simulations of the classic lid-driven cavity flow for steady states. The novelty of the present algorithm resides in the construction of the information transferring process, in which, for a full cycle, the numerical simulation starts on the coarse mesh, transferring to medium mesh and then streams to the fine mesh through a prolongation operator. Afterwards, instead of using a restriction operator, the fluid information jumps back directly from the fine mesh to the coarse mesh via an assignment operator. The accuracy and efficiency of the simplified new algorithm are validated by comparing the results obtained when employing the classic V-cycle multigrid algorithm and the traditional lattice Boltzmann method with uniform Cartesian grid This research was founded by the project provided by the Northwestern Polytechnical University (G2021KY05103). This work was also sponsored by the foundation of National Key Laboratory of Science and Technology on Aerodynamic Design and Research (No. 614220121030101)

The selective deoxygenation of palm oil to produce green diesel has been investigated over Ni catalysts supported on ZrO2 (Ni/Zr) and CeO2–ZrO2 (Ni/CeZr) supports. The modification of the support with CeO2 acted to improve the Ni dispersion and oxygen lability of the catalyst, while reducing the overall surface acidity. The Ni/CeZr catalyst exhibited higher triglyceride (TG) conversion and yield for the desirable C15–C18 hydrocarbons, as well as improved stability compared to the unmodified Ni/Zr catalyst, with TG conversion and C15–C18 yield remaining above 85% and 80% respectively during 20 h of continuous operation at 300 oC. The high C17 yields also revealed the dominance of the deCOx (decarbonylation/decarboxylation) pathway. A fully comprehensive process simulation model has been developed to validate the experimental findings in this study, and a very good validation with the experimental data has been demonstrated. The model was then further utilised to investigate the effects of temperature, H2 partial pressure, H2/oil feed ratio and LHSV. The model predicted that maximum triglyceride conversion was attainable at reaction conditions of 300 °C temperature, 30 bar H2 partial pressure, H2/oil of 1000 cm3/cm3 feed ratio and 1.2 h−1 LHSV., MAG and NDC gratefully acknowledge that this researched was co-financed by Greece and the European Union (European Social Fund-ESF) through the Operational Programme “Human Resources Development, Education and Lifelong Learning” (MIS-5050170). KP and SA acknowledge the financial support from the Abu Dhabi Department of Education and Knowledge through the grant AARE-2019-233 and the support from Khalifa University through the grant RC2-2018-024. VS acknowledges the ICTS ELECMI-LMA for offering access to their instruments and expertise.

An investigation of various eddy viscosity models for accurate scale-resolving simulation of aerodynamics and aeroacoustics of a turbulent jet is presented. The models are considered from the perspective of solving the so-called gray area problem. This problem is related to nonphysical delay in the transition from Reynolds-averaged Navier–Stokes (RANS) to large-eddy simulation (LES) in hybrid RANS–LES approaches such as detached eddy simulation (DES) when applied to shear-layer flows. The performance of recently developed dynamic adapting subgrid length scales ([Formula: see text], [Formula: see text], and [Formula: see text]) and subgrid LES models ([Formula: see text] and S3QR) separately and together is demonstrated. The object of the investigation is an immersed subsonic turbulent jet. The simulations are carried out on a set of refining meshes using two different scale-resolving numerical algorithms with basic and higher-accuracy schemes on unstructured meshes. The evaluation of various eddy-viscosity models within the DES approach is mostly focused on the analysis of far-field noise. The study has clearly demonstrated the importance of both a numerical scheme and a subgrid turbulence model. The results show that some of the considered techniques provide the necessary accuracy to predict the noise generated by a turbulent jet. The features of the considered approaches are identified and discussed. Recommendations are formulated for the choice of the LES model and subgrid length scale for this kind of problem. The work of Jesús Ruano, F. Xavier Trias, and Joaquim Rigola has been financially supported by the project RETOtwin (PDC2021- 120970-I00) funded by MCIN/AEI/10.13039/501100011033 and European Union Next Generation European Union / Plan de Recuperación, Transformación y Resiliencia (EU/PRTR). The work of Alexey P. Duben and Andrey V. Gorobets was carried out within the state assignment of Ministry of Science and Higher Education of the Russian Federation (Theme No. 122041100137-4). NOISEtte computations were carried out using the equipment of the shared research facilities of high performance computing (HPC) computing resources at Lomonosov Moscow State University, the computing resources of the federal collective usage center Complex for Simulation and Data Processing for Mega-science Facilities at National Research Centre (NRC) “Kurchatov Institute” (http://ckp.nrcki.ru/), and the hybrid supercomputer K60 installed in the Supercomputer Centre of Collective Usage of Keldysh Institute of Applied Mathematics of Russian Academy of Sciences (KIAM RAS). The authors thankfully acknowledge these institutions.

Cardiovascular diseases are the leading cause of mortality, morbidity, and hospitalization around the world. Recent technological advances have facilitated analyzing, visualizing, and monitoring cardiovascular diseases using emerging computational fluid dynamics, blood flow imaging, and wearable sensing technologies. Yet, computational cost, limited spatiotemporal resolution, and obstacles for thorough data analysis have hindered the utility of such techniques to curb cardiovascular diseases. We herein discuss how leveraging machine learning techniques, and in particular deep learning methods, could overcome these limitations and offer promise for translation. We discuss the remarkable capacity of recently developed machine learning techniques to accelerate flow modeling, enhance the resolution while reduce the noise and scanning time of current blood flow imaging techniques, and accurate detection of cardiovascular diseases using a plethora of data collected by wearable sensors.

In contemporary power plants, poor air temperature is one of the primary causes of rising unit temperatures and deteriorating boiler performance. The primary issue with an air preheater is air leakage on the gas flue side, which results in poor thermal performance. The high ash content of Indian coal exacerbates the issues with air tube heating. Air preheaters re developed to fulfill operational needs while taking into account the most important factors. Heat transmission, leakage, and pressure reduction are all factors to consider. The performance of the air-conditioning heater is being evaluated in this study using the Fluent 14.0 analytical tool from Computational Fluid Dynamics (CFD).

Seepage-induced instabilities pose a challenge in many geotechnical applications. Particle-scale mechanisms govern the initiation of instability. However, current understanding is based on a macro-scale perspective that draws on continuum mechanics. Recent developments in imaging and numerical analysis can provide the particle-scale fundamental perspective needed to develop a comprehensive insight. This contribution demonstrates the value of combining particle-scale experimental and numerical studies. The experiments consider transparent soil samples created using refractive image matching and monitored by particle image velocimetry (PIV). Three-dimensional pore topology is extracted from a series of two-dimensional images and imported into computational fluid dynamics (CFD) simulations. Permeability is estimated by three distinct approaches: using flow rate, PIV- and CFD-generated data. The flow fields obtained from PIV and CFD are in good agreement considering both flow rate contour plots and flow rate distributions; this demonstrates the successful reconstruction of three-dimensional pore structure and flow-field analysis. The comparison also reveals that the side boundary effects in CFD simulations are constrained within a limited region. The multi-plane results characterise the variance of flow velocity with the three-dimensional pore topology. Finally, the fluid–particle interactions obtained from CFD results show a larger variance in the angular particle packings.

Abrasive flow jet machining (ASJM) is modern manufacturing technique which uses comparatively low-pressure abrasive flow jet for machining various machined surfaces like holes, channels and intricate shapes which is not possible from conventional machining processes. The effect of abrasive particle concentration on the impacting slurry velocity on the surface was examined in the present CFD simulation, resulting in target surface erosion. To predict the impact velocity of abrasive particles hitting the surface, a 2D CFD model was used. The depth of machined surface, surface irregularity and surface removal rate at normal incidence mainly depend on the KE of particle, impact angle, etc. in line with previously published research work on highly pressurised air and water driven abrasive jet. In the present work CFD simulation is performed to predict the effect of solid particle concentration on the impacting slurry jet velocity at the target surface and also turbulence kinetic energy near the surface is studied. As per the CFD results the simulation model predictions the velocity of impacting particle goes on decreasing due to internal frictional resistance between solid and liquid phase and it shows scope of further parametric analysis in this area.

When agricultural goods begin to be transported by those temperatures where value added products can be transported, cold room assessments in industrial applications must be validated. Computational feedback can improve the process consistency. Data on coolant and boundary dynamics can be evaluated by means of computer fluid dynamics (CFD). Air speed and air temperature are the distribution parameters in this analysis. When the vegetable temperature is preserved with less variations in the storage room, as well as the required air distribution, the best effects of proper preservations are achieved. With proper air circulation, temperature difference is minimised. Air speed is necessary to protect the cold storage of agricultural products. This project's main objective was to observe the decrease in temperature when PCMs are used within the cold storage space. Most of the experimental results demonstrated that in the event of regular openings of doors, also in the context of electricity failures using PCM, the temperature retained inside the cool space was 1–4.5 °C lower than without PCM, even in the cases of electrical failures using PCM. The present study focuses on applying guidelines to enhance cold room technology for improved outcomes in cold storage. Present work discussed about the reference methods and the techniques used in previous literature with future recommendations.

This study addresses performances and behaviors of the multi-cross-section HAWT blade design with and without fences. The FX66-S-196 V, FX63-137 S and SG6043, supercritical airfoils were used and distributed along the blade radius; further, the NACA4412 single-cross-section HAWT blade having the same dimensions was used to compare the behaviors and overall performances of all the blades. Analyses were then performed numerically using blade elements momentum BEM theory with a self-code (F.90) and CFD as well as experimentally with three multi-cross-section blades designed using SOLIDWORKS and 3D- printed with polylactic acid. the multi-cross-section HAWT blades show good performance compared with the single- cross-section blade, with an approximately 8% increase in power coefficient, i.e., 40 W, for a miniature wind turbine (127 cm diameter 500 W output power) and greater improvements for wind turbines with large diameters. The fences were designed using boundary layer theory and installed on multi-cross-section blades in experimentally determined positions. The fences showed high performance, with a 16% increase in total power coefficient and high flutter stability.

In the current study, numerical analysis of passive control flow with a control rod for Ahmed body is performed at different slant angles and velocities and placed rod locations on the slant surface. The aim of the study is to improve aerodynamic performance by preventing flow separation on the slant surface of Ahmed body using a control rod. This passive flow control method uses a control rod that has not been applied for simplified ground vehicles before. Therefore, it can be said that this study is a new example in point of a passive flow control application for Ahmed body. The solution of the study is performed by using the Computational Fluid Dynamics (CFD) method. The solutions are firstly performed for baseline geometry, and the results are compared with experimental data reported in the literature for validation. CFD solutions are carried out by means of the ANSYS and RNG k-(sic) turbulence model is used to simulate flow -field since it captures the effect of turbulent flow. The solutions used a control rod with a 20 mm diameter performed at a dimensionless location (X/L=0.057 and 0.153) for Ahmed body. The results are presented visually in the figures, and drag coefficient values are also given in Table format. It is concluded that the rod application is useful for some specified slant angles and velocities since flow separation delays and suppresses the slant surface. The maximum drag reduction is achieved at about 6.153% at a slant angle of 35 degrees and 20 m/s velocity of air, and location of control rod of 0.057, while the minimum drag reduction is about 1.048% at slant angle of 25 degrees and velocity of air at 40 m/s and location of control rod of 0.153.

In this work we study the blood dynamics in the pulmonary arteries by means of a 3D-0D geometric multiscale approach, where a detailed 3D model for the pulmonary arteries is coupled with a lumped parameters (0D) model of the cardiovascular system. We propose to investigate three strategies for the numerical solution of the 3D-0D coupled problem: the Splitting-Explicit and Implicit algorithms, where information are exchanged between 3D and 0D models at each time step at the interfaces, and the One-Way algorithm, where the 0D is solved first off-line. In our numerical experiments performed in a realistic patient-specific 3D domain with a physiologically calibrated 0D model, we discuss first the issue on instabilities that may arise when not suitable connections are considered between 3D and 0D models; second we compare the performance and accuracy of the three proposed numerical strategies. Finally, we report a comparison between a healthy and a hypertensive case, providing a preliminary result highlighting how our method could be used in future for clinical purposes.

Purpose This study aims to predict dynamic responses of aileron and spoiler control surfaces in subsonic flight via the use of surrogate models. The prepared reduced order models prove useful when quick estimations for a large number of variations are required. Design/methodology/approach The linear frequency domain (LFD) method was used for the simulation study. Each surrogate contained a database of 100 control surface dynamic responses over a spectrum of 200 harmonics computed with LFD. To interpolate new results, the DLR surrogate modelling toolbox, SMARTy, was used. The database’s samples were prepared in a Halton sequence, making interpolation reliable. The surrogate’s parameter space was the Mach number, Reynold’s number, angle of attack, control surface deflection angle and the control surface chord length. Findings The LFD method proved effective for the mentioned purpose: the surrogates were accurate, up to 15% of relative error, in reproducing dynamic responses of aileron and spoiler deflections at low speed, within the limitations of flow field linearity, as well as surrogate prediction capability. The restrictions of the surrogate, and the reasoning thereof, are also presented in detail in the study. Future load alleviation studies are a potential of the findings here. Originality/value LFD is an innovative technique for load prediction and alleviation studies. This paper provides a reference for engineers wishing to use the method for the two mentioned control surfaces, or the like.

The linearity assumption is widely used when acquiring the hydrodynamic coefficients of a floating structure. However, the linear damping is frequently underestimated, especially for the natural frequency. To investigate the sloping seafloor effects on the damping terms of a single module of a semi-submersible Very Large Floating Structure (VLFS), this paper revisits the conventional formulation and further proposes the direct integration method for obtaining the linear and quadratic damping coefficients from free-decay tests. Numerical free-decay simulations of the single module over variable bathymetry are carried out by the CFD numerical tank. Corresponding model tests are also implemented to verify and validate against the numerical solutions. The effects of the sloping seafloor, as well as the water depth, on the hydrodynamic coefficients are investigated based on the validated CFD modeling. Both numerical and experimental results indicate that the acquisition of the linear and quadratic damping coefficients is sensitive to the data-processing and identification approaches. For the case studied in present paper, the identification errors introduced by the conventional method are 1.5 % while they are 0.5 % using the direct integration method. The quadratic damping coefficient for heave mode decreases about 10.4 % when the sloping angle increases from 0 to 6 deg.

A novel single-use bioreactor was recently introduced to the market that is agitated by impellers suspended on flexible ropes rather than a rigid shaft. Computational fluid dynamics (CFD) models were created and validated by particle image velocimetry (PIV) to predict the bioreactor’s fluid flow and mixing. The data were then used to scale-up a Spodoptera frugiperda, subclone 9 (Sf9) insect cell-based production of recombinant adeno-associated virus (AAV) from a benchtop glass bioreactor to the single-use system with 30 L working volume. This viral vector is one of the most commonly used in gene therapies. The volumetric power input was kept constant while maintaining reasonable mixing times and shear stresses between the scales. Peak cell densities of up to 7.2·10^6 cells/mL and maximum virus titers of 1.7·10^11vg/mL were achieved. Similar cell growth and metabolite profiles further proved the successful process transfer between the two geometrically non-similar bioreactor systems. The pilot bioreactor yielded between 3.3 and 4.8·10^15 vg that, depending on the therapy, can be sufficient for the treatment of a single patient.

Based on thermoelectric analogy method, a thermal network model coupled with electromagnetic loss is presented. According to the actual structure of dry-type transformer windings, an accurate thermal network is established. Considering the distribution characteristics of heat source along cooling ducts inside the dry-type transformer, the thermal parameters such as heat flux and convective heat transfer coefficients are calculated by finite element method analysis (FEM) and computational fluid dynamics (CFD). Based on temperature rise experiment, the hottest spot located at the top of outmost high voltage winding is 151.8 °C, which verified the correctness of thermal network model.

Background: Thousands of refrigerated containers transport fresh fruit and vegetables to feed the world yearly. These containers should preserve fresh-food quality as uniformly as possible throughout the cargo. Scope and approach: Several simulation studies have suggested the presence of a systematic hot spot in these containers near the supply-air inlet when warm cargo is cooled down in the container. Induced by airflow recirculation inside the ventilated packaging, the hot spot is located at the bottom of the pallets near the refrigeration unit. The fruit at the bottom of these pallets is well known to be exposed to cold air. However, the existence and impact of this apparent hot spot were not acknowledged explicitly. Interestingly, full-scale experiments and computational fluid dynamics (CFD) simulations contradict the existence of this recirculation-zone-induced hot spot. Key findings and conclusions: We analyzed the literature and the physical phenomena at play to identify if and why this recirculation-driven hot spot occurs. We found that the airflow recirculation can be partially hidden in full-scale experiments and that we are often not looking for it at that location. Physically, the presence of the recirculation zone is plausible. The CFD simulations that predict this zone include all relevant physical processes. However, we still need proof by detailed full-scale experiments to confirm its existence. It is likely that the recirculation only occurs in some ventilated shipments, but then we need to identify for which shipments this happens. If this recirculation zone is present in a ventilated cargo of perishables, we need to solve this problem urgently. We suggest a roadmap with steps to do so. Otherwise, we would be systematically losing food quality in many shipped containers. Besides slowing down fruit cooling, such a recirculation vortex can trap respiration heat, moisture, and metabolic gases. Mitigating this hot spot thus can considerably impact the quality of the fruit and vegetables shipped worldwide.

We are developing a universal, advanced ventricular assist device (AVAD) with automatic pressure regulation suitable for both left and right ventricular support. The primary goal of this computational fluid dynamics (CFD) study was to analyze the biventricular performance of the AVAD across its wide range of operating conditions. An AVAD CFD model was created and validated using in vitro hydraulic performance measurements taken over conditions spanning both left ventricular assist device (LVAD) and right ventricular assist device (RVAD) operation. Static pressure taps, placed throughout the pump, were used to validate the CFD results. The CFD model was then used to assess the change in hydraulic performance with varying rotor axial positions and identify potential design improvements. The hydraulic performance was simulated and measured at rotor speeds from 2,300 to 3,600 revolutions/min and flow rates from 2.0 to 8.0 L/min. The CFD-predicted hydraulic pressure rise agreed well with the in vitro measured data, within 6.5% at 2300 rpm and within 3.5% for the higher rotor speeds. The CFD successfully predicted wall static pressures, matching experimental values within 7%. High degree of similarity and circumferential uniformity in the pump's flow fields were observed over the pump operation as an LVAD and an RVAD. A secondary impeller axial clearance reduction resulted in a 10% decrease in peak flow residence time and lower static pressures on the secondary impeller. These lower static pressures suggest a reduction in the upwards rotor forces from the secondary impeller and a desired increase in the pressure sensitivity of the pump. The CFD analyses supported the feasibility of the proposed AVAD's use as an LVAD or an RVAD, over a wide range of operating conditions. The CFD results demonstrated the operability of the pump in providing the desired circumferential flow similarity over the intended range of flow/speed conditions and the intended functionality of the AVAD's automated pressure regulation.

Curved tip extensions are among the rotor innovation concepts that can contribute to the higher performance and lower cost of horizontal axis wind turbines. One of the key drivers to exploit their advantages is the use of accurate and efficient computational aerodynamic models during the design stage. The present work gives an overview of the performance of different state-of-the-art models. The following tools were employed, in descending order of complexity: (i) a blade-resolved Navier Stokes solver, (ii) a lifting line model, (iii) a vortex-based method coupling a near-wake model with a far-wake model, and (iv) two implementations of the widely used blade element momentum method (BEM), with and without radial induction. The predictions of the codes were compared when simulating the baseline geometry of a reference wind turbine and different tip extension designs with relatively large sweep angle and/or dihedral angle. Four load cases were selected for this comparison, to cover several aspects of the aerodynamic modeling: steady power curve, pitch step, extreme operating gust impact, and standstill in deep stall. The present study highlighted the limitations of the BEM-based formulations to capture the trends attributed to the introduction of curvature at the tip. This was true even when using the radial induction submodel. The rest of the computational methods showed relatively good agreement in most of the studied load cases. An exception to this was the standstill configuration, as the blade-resolved Navier-Stokes solver was the only code able to capture the highly unsteady effects of deep stall.

This paper is a short retrospective review of the predictive methods of turbulent flows in Computational Fluid Dynamics over the last 50 years since the first development of computers. The different schools of turbulence modeling are presented with the aim to guide both users and researchers involved in numerical simulation of turbulent flows.; Cet article est une courte rétrospective de synthèse des méthodes prédictibles des écoulements turbulents.Des simulations des écoulements sur ces 50 dernières années depuis les premiers développement des ordinateurs.Les différentes écoles de la modélisation des turbulences sont présentées dans le but de guider à la fois les utilisateurs et les chercheurs impliqués en simulation numérique des écoulements turbulents.

Occurrences such as the global climate change have presented critical challenges to humanity and necessitated studies into how greenhouse gas emissions can be minimized. One practical solution is the generation of power from renewable and sustainable sources; hence, tidal current energy which, however, also gives rise to the concept of fluid-structure interaction (FSI). The pressure and fluid flow aspects affect the structural deformations and the structural deformations in turn affect pressure and flow. This paper presents a perspective review of FSI based optimisation in tidal turbines with a focus on low-order aerodynamic, computational fluid dynamics (CFD) and structural modeling. It was acknowledged that, to aid humanity amidst the issue of using renewable or non-renewable sources of energy, practical solutions such as generating renewable energy from sustainable sources are effective. Tidal current energy was found to be one of the most reliable solutions but further studies regarding its practicality was advised.

Mechanical Ventilation with Heat Recovery (MVHR) systems are gaining increasing interest in buildings with low energy demand, for improvement of the Indoor Air Quality (IAQ) and reduction of the ventilation energy loss. In retrofitted buildings, MVHRs are often integrated with an additional air heater to cover space heating demand. Hence, evaluation of the interactions between MVHR and heat emitter, and their effects on indoor airflow characteristics is of significant importance. The present study aims to investigate effects of a combined MVHR-fan-coil system in heating mode on IAQ and thermal comfort parameters inside a retrofitted room, by means of a computational fluid dynamic (CFD) code. The proposed CFD model is validated by comparing the numerical results with experimental data. The results yielded by numerical simulations allow evaluating the indoor environmental quality characteristics as well as addressing the MVHR and fan coil interactions. The results indicate that the airflow discharged from the fan coil could have a significant impact on the age of the air; while it provides a desirable thermal comfort condition within the room, it may hinder to some extent delivery of the fresh air to the occupied zone due to creation of counterflow fields. Furthermore, it is shown that although increasing the fan speed (ON mode) would slightly enhance the air change efficiency, the OFF mode yields not only a better distribution of the fresh air but also a higher ventilation efficiency than when fan coil operates.

Thermal comfort inside classrooms located in an institutional building is examined as a function of air temperature, relative humidity and wind velocity. The effect of east-west orientation on the thermal comfort inside the classrooms located in different floor levels is understood based on field experiments and validated using computational fluid dynamics simulations. The air temperature inside the classrooms shows an increasing trend with the floor level. Air temperature and relative humidity inside the classrooms reveal an inverse relationship as a function of east-west orientation with different floor level. As time progresses, the air temperature inside classrooms located on the eastern side of the building is apparently higher than rooms situated on the western side of the building, both field experiments and simulation acknowledge the same. Appropriate reasons have been proposed behind the discussed phenomenon using computational fluid dynamics simulation.

Computational fluid dynamics model parameters highly depend on the storage structure, grain conditions, and airflow properties. Solution methods obtained for the lab-scale bins cannot be extrapolated for a relatively large on-farm silo. To validate the above hypothesis, a model was developed and validated with stored barley aeration in a 1000t silo. A mathematical function was used to initialize the discrete initial conditions in the silo followed by using DEFINE_macros to execute parallel computing. Time-step analysis was conducted followed by optimization of the solution methods in terms of the accuracy and time frame of the model's output. Results showed that with a time-step of 4 s, temperature and moisture error were 1.1-1.7 degrees C and 0.3% wb while mean relative deviation were 3.1-4.4% and 2.2%, respectively. COUPLED algorithm resulted in a similar accuracy as of SIMPLE scheme except within spatial and transient formulations. However, the former algorithm was observed to take almost 190% more time than the latter scheme, limiting the simulation efficiency in an on-farm silo. Green Gauss Node-based gradient technique was found to be the appropriate for discretizing large silos. Model showed 45 kJ kg(-1) energy emission that decreased the cooling potential of air in silo. As field evaluation of aeration strategies are time-consuming, this model can be used to obtain results that could shape the stored grain management practice. Refereed/Peer-reviewed

In hazardous gas leakage accidents in chemical clusters, quickly and accurately locating the diffusion source via mobile sensors (searcher) can effectively speed up emergency response. While state-of-the-art researches designed kinds of autonomous sensing and searching techniques, e.g. cognitive-based strategies to complete the localization of the leakage source; the current studies cannot meet chemical cluster’s requirements with complex road network constraints and spatial scales. To address this problem, we firstly combine a cognitive search strategy with great theoretical performance (Entrotaxis algorithm) with an intermittent search strategy and propose a fresh searching algorithm, namely Entrotaxis-Turn (ET). The hybrid algorithm can make use of the triggered turn motion to bypass obstacles to avoid falling into a loop, thereby improving the success rate and saving the searching time. Secondly, we extend the ET algorithm to the multi-robot collaboration pattern (Multi-ET algorithm), in which each mobile sensor shares the information collected along its route with each other. To reveal the performance of the proposed algorithms, a simulation scene is built in a typical chemical cluster scene and diffused gas is generated based on the advection-diffusion equation. Through Monte Carlo simulations, the optimal parameter combinations in the ET and Multi-ET algorithm are obtained. Finally, a verification experiment is carried out based on the simulation scene generated by the computational fluid dynamics (CFD) model. Results show that compared with the Entrotaxis algorithm, the efficiency and success rate of the ET algorithm are dramatically improved. Moreover, the Multi-ET algorithm obtains the optimal source searching performance.

Modeling of fluid-structure interactions (FSIs) between the deformable arterial wall and blood flow is necessary to obtain physiologically realistic computational models of cardiovascular systems. However, lack of information on the nature of contact between the outer vessel wall and surrounding tissue presents challenges in prescribing appropriate structural boundary conditions. Imaging techniques used to visualize wall deformation in vivo may be useful for estimating simulation parameters that capture the effects of both vascular composition and surrounding tissue support on the vessel wall displacement. Here, we present a method to calibrate external tissue support parameters in FSI simulations against four-dimensional ultrasound (4DUS) of the murine thoracic aortae. We collected ultrasound, blood pressure, and histological data from several mice infused with angiotensin II (n = 4) and created a representative model of healthy and diseased (at 28 days post-angiotensin II infusion) murine aortae. We ran pulsatile FSI simulations after accounting for increased arterial wall stiffness with varying levels of tissue support, which demonstrated non-trivial variation in not only structural quantities, such as vessel wall deformation, but also hemodynamic quantities, such as wall shear stress across simulations. Furthermore, we compared simulation results with in vivo 4DUS imaging data and observed that the suitable range of the tissue support spring parameter was identical for both healthy and diseased states. This indicated that the same tissue support parameter estimates could be used for modeling the healthy and diseased states of the vessel, provided that changes in arterial wall stiffness had been considered. We anticipate this technique and the tissue support estimates reported herein will help inform computational models of blood flow and vasculature that incorporate the influence of external tissue.

Tecnologia FCT/MCTES (PIDDAC) and Centro2020, Grant/Award Number: UIDB/04044/2020 and UIDP/04044/2020; Associate Laboratory ARISEand PAMI, Grant/Award Number: LA/P/0112/2020 and ROTEIRO/0328/2013; Research Unit INESC MN and FCT, Grant/Award Number: UID/05367/2020 and UIDB/50022/2020. Aim: This study aimed to experimentally validate a computational fluid dynamics (CFD) model, using micro-particle image velocimetry (micro-PIV) measurements of the irrigation flow velocity field developed in confluent canals during irrigation with a side-vented needle. Methodology: A microchip with confluent canals, manufactured in polydimethylsiloxane was used in a micro-PIV analysis of the irrigation flow using a side-vented needle placed 3 mm from the end of the confluence of the canals. Velocity fields and profiles were recorded for flow rates of 0.017 and 0.1 ml/s and compared with those predicted in CFD numerical simulations (using a finite volume commercial code –FLUENT) for both laminar and turbulent regimes. Results: The overall flow pattern, isovelocity and vector maps as well as velocity profiles showed a close agreement between the micro-PIV experimental and CFD predicted data. No relevant differences were observed between the results obtained with the laminar and turbulent flow models used. Conclusions: Results showed that the laminar CFD modelling is reliable to predict the flow in similar domains. info:eu-repo/semantics/publishedVersion

Floating treatment wetlands (FTWs) use plants' roots for water quality improvement. The plants are supported by a buoyant structure deployed at the water surface. The roots form a porous zone beneath the structure and remove pollutants carried in suspension through filtering, absorption and uptake. This paper used CFD simulation to model FTWs arranged in series and spanning the channel width and to study the effects of root length and spacing between FTWs on flow distribution and mass removal. The root zone was modelled as a porous media, and removal was computed using first-order decay, for which a range of removal constants was tested. Longer roots increased the reactive volume of the root zone, which increased the fraction of pollutant inflow entering the FTWs. Increasing the distance between FTWs allowed greater mixing between water that went through and beneath the upstream FTW. This increased the concentration entering each FTW, which enhanced mass removal per FTW. However, a larger distance between FTWs reduced the number of FTWs in the channel, reducing the reactive volume. In the tradeoff between mixing and reactive volume, the reactive volume was more important, such that total removal in the channel increased with longer roots and more units of FTW (shorter gap distance). However, removing the gap entirely was detrimental, as FTWs in series removed more mass than a continuous FTW of same volume. This study points to two design recommendations for FTWs in series. First, if resources for building FTWs are not limiting, but the channel length is, it is preferable to prioritize higher reactive volume (shorter gap distance) to achieve maximum removal per channel length. Second, if resources for FTWs are limiting, but channel length is not, it is better to place the FTWs with a longer gap distance, preferably along enough to allow mixing over the full depth between FTWs, as this will achieve maximum removal per FTW. Refereed/Peer-reviewed

Liquid–solid fluidized beds (LSFB) modeling validation is crucial for establishing design rules and monitoring tools. However, it generally relies on comparing global variables, which overlook dynamic features that influence reaction outputs. This work aims to implement time series analysis tools to compare Radioactive Particle Tracking data with a simulation consisting of Computational Fluid Dynamics coupled with Discrete-Element Method. Experiments have been performed in a pilot-scale LSFB of calcium alginate spheres fluidized with a calcium chloride solution. The Diks’ test indicates that the simulation can capture the LSFB behavior. It also allows diagnosing flow regime transitions from the simulation. Trends of solid dispersion coefficients and mixing times predicted by the simulation are in good agreement with the experiments.

Vessels entering and leaving ports are faced with the challenge of maneuvering due to weather conditions, bad currents, and traffic dues to congestion in the channels near coastal waters. In order to berth or manoeuver properly the use of tugs is necessary which incurs more cost and more turnaround time for the vessel owner. Over the years, bow thrusters have been introduced to aid easy maneuverability despite these conditions in order to eliminate the cost of hiring tugs as well as reduce turnaround time for the vessels. In this project, a 4-blade bow thruster propeller of 500mm diameter was successfully modelled using Solidworks 2021 (CAD) software. Computational flow dynamics (CFD) was done using flow simulation in Solidworks 2021 and 260 iterations was carried out. The velocity at the body of the propeller was found to be 13.67m/s while the velocities at the front and back of the propeller was 6.841m/s. The values for the performance factors were also gotten for a varying range of BT propeller diameters and charts were develop to show the relationship between the propeller diameter and the performance factors necessary for maneuvering a vessel. It can be concluded that the performance factors necessary for maneuvering a vessel is dependent on the diameter of the bow thruster. For further studies, number of thruster to be fitted to the bow or stern of a vessel should be considered for larger vessel sizes.

The modelling of wave-structure interaction (WSI) has significant applications in understanding natural processes as well as securing the safety and efficiency of marine engineering. Based on the technique of Computational Fluid Dynamics (CFD) and the open-source simulation framework - OpenFOAM, this paper provides a state-of-the-art review of WSI modelling methods. The review categorises WSI scenarios and suggests their suitable computational approaches, concerning a rigid, deformable or porous structure in regular, irregular, non-breaking or breaking waves. Extensions of WSI modelling for wave-structure-seabed interactions and various wave energy converters are also introduced. As a result, the present review aims to help understand the CFD modelling of WSI and guide the use of OpenFOAM for target WSI problems.

Sudden releases of pressurised hydrogen may spontaneously ignite by the so-called “diffusion ignition” mechanism. Several experimental and numerical studies have been performed on spontaneous ignition for compressed hydrogen at ambient temperature. However, there is no knowledge of the phenomenon for compressed hydrogen at cryogenic temperatures. The study aims to close this knowledge gap by performing numerical experiments using a computational fluid dynamics model, validated previously against experiments at atmospheric temperatures, to assess the effect of temperature decrease from ambient 300 K to cryogenic 80 K. The ignition dynamics is analysed for a T-shaped channel system. The cryo-compressed hydrogen is initially separated from the air in the T-shaped channel system by a burst disk (diaphragm). The inertia of the burst disk is accounted for in the simulations. The numerical experiments were carried out to determine the hydrogen storage pressure limit leading to spontaneous ignition in the configuration under investigation. It is found that the pressure limit for spontaneous ignition of the cryo-compressed hydrogen at temperature 80 K is 9.4 MPa. This is more than 3 times larger than pressure limit for spontaneous ignition of 2.9 MPa in the same setup at ambient temperature of 300 K.

In this paper, we revisit a turbulent mixing of gas and air in a gas burner with computational fluid dynamics (CFD) models. The quality of such a turbulent mixture is based on temperature, pressure, and velocity distributions as well as the distributions of different molecules, turbulent kinetic energy, and turbulent dissipation rate. In order to identify a precise combination of a gas and air mixture in a gas burner, which directly influences the quality of the combustion flame and reduces the amount of carbon monoxide (CO) emission in flue gases, thermodynamic principles are utilized based on the balancing ratio of molecular weights and the balancing ratio of mass flows between gas and air. Moreover, input parameters, such as volume flow rates, pressure, mass ratio, temperature, turbulent kinetic energy, and turbulent dissipation rate, are judiciously chosen with proper boundary conditions for both axisymmetric two-dimensional and three-dimensional models. It is confirmed that the effectiveness of gas and air mixture and combustion depends on the gas burner model, more specifically, on the sizes and locations of gas and air inlets and outlets as well as operation conditions.

The three-dimensional computational fluid dynamics (3D-CFD) of a pulsating flow applied to the fluid catalytic cracking (FCC) reaction was investigated in the riser of a circulating fluidized bed reactor. The kinetic parameters of the FCC and coke burning reactions for predicting the reactant conversion and product yield percentages were applied. To increase the reactant conversion level and product yield, the effect of the pulsating flow operating parameters was considered using a 2k statistical experimental design with four factors (amplitude, frequency, types of the waveform, and amplitude ratio). The 3D-CFD simulation was successfully validated from the experimental literature data. The frequency and type of the waveform were found to be the significant operating parameters. The expression of the fitted regression model and response surface contour were derived and revealed that the pulsating flow provides a higher reactant conversion level and product yield percentages compared to a non-pulsating or steady flow.

Enhancing damping characteristic is one of the effective methods to solve the instability problem of the rotor system. The three-dimensional numerical analysis model of scallop damper seal was established, and the effects of inlet pressures, preswirl ratios, rotational speeds, interlaced angles and seal cavity depths on the rotordynamic characteristics of scallop damper seal were studied based on dynamic mesh method and multi-frequencies elliptic whirling model. Results show that the direct stiffness of the scallop damper seal increases with decreasing inlet pressure and increasing rotational speed and cavity depth. When the seal cavity is interlaced by a certain angle, which shows positive direct stiffness. The effective damping of the scallop damper seal increases with the increasing inlet pressure, the decreasing preswirl ratio and the rotational speed and cavity depth. There exists an optimal interlaced angle to maximize the effective damping and the system stability. The leakage of the scallop damper seal is significantly reduced with decreasing inlet pressure. The preswirl will reduce the leakage flowrate, and the rotational speed has a slight effect on the leakage performance. The leakage of the scallop damper seal decreases with increasing seal cavity depth.

An integrated boost impeller can effectively improve the suction performance of an aircraft hydraulic pump (AHP). It must be designed very carefully; however, few studies thus far have investigated boost impellers. To explore the effect of the boost impeller, this study developed a three-dimensional computational fluid dynamics (CFD) model for an AHP based on the k-e turbulence model and full cavitation model. The results of verification tests demonstrated that the model is reliable for simulating the delivery characteristics of piston pumps and the boost capacity of the inlet impeller. Steady-state simulations reveal that the boost impeller can remarkably improve the suction performance and mitigate the cavitation damage due to insufficient fluid filling while only consuming a small proportion of the total input power. Transient-state simulations show that the pump with an impeller is more capable of catching up with a sudden increase in flow demand, and it has a lower suction flow ripple and impact. However, such a boost impeller also has some limitations such as magnifying the suction pressure fluctuation and having little effect on mitigating the cavitation caused by the back-flow jet.

Although considerable methods have been developed for the performance evaluation of signalized intersections using sampled vehicle trajectories, most of them aim at estimating a single parameter and cannot describe the entire arrival-departure process of the traffic flow. This significantly constrains the application of these methods for a comprehensive evaluation and efficient optimization of signalized intersections. In this paper, we propose a cumulative flow diagram (CFD) estimation and prediction method using sampled vehicle trajectories. It can be used to calculate multiple performance measures--traffic volume, queue length, average delay, and total delay--based on the estimated CFD for the current signal timing plan. Concurrently, it can be further employed for signal control optimization based on the predicted CFDs for candidate signal timing plans. The core idea of the proposed method is to generate the cumulative arrival curve based on the arrival characteristics of the sampled vehicles, and then fit the queue leaving points to obtain the cumulative departure curve. Thereby, given the current or any candidate signal timing plan, we can estimate or predict the CFDs by updating the sampled vehicle arrivals. The proposed method is evaluated using both simulation and empirical data. The simulation results yield that the average estimation error of the four performance measures is 10.3% under a real-world level penetration rate of 10%. Meanwhile, similar accuracies are achieved for the CFD prediction. The empirical results show that under a penetration rate of 8.6%, the estimation errors of the traffic volume and queue length are 2.7% and 3.3%, respectively.

Bridge aerodynamic studies are essential in ensuring the safety and acceptable performance of long-span bridges vulnerable to the effects of crosswinds. Aerodynamic studies were traditionally carried out in wind tunnel facilities, but there are now greater opportunities for using computational fluid dynamics modelling. Few studies of three-dimensional aerodynamic simulations of lightweight vehicles on bridges exist but there has been limited validation and verification work done to date. In the study reported in this paper, three-dimensional computational fluid dynamics models were developed for the Queensferry Crossing cable-stayed bridge in Scotland, containing wind shields and sample vehicles. The models considered the wind effects from a range of yaw wind angles and subsequently determined the aerodynamic coefficients of vehicles. The models were verified by means of a mesh sensitivity study, a domain sensitivity study and comparisons with wind-tunnel test results. The models were then validated by using the same modelling process with a different type of wind shield, and again comparing results with wind-tunnel test data for the same configuration. Results demonstrated that the modelling can determine the aerodynamic coefficients to a similar level of accuracy to that of wind tunnel tests. University College Dublin China Scholarship Council 2022-09-28 JG: PDF replaced with correct version. Titles conflict has been verified with the author. Ahead of print to check citing and date details in 6 m

The motivation of this work is to produce an integrated mathematical formulation for the numerical modelling of material response due to detonation wave loading. In particular, we are interested to capture miscible and immiscible behaviour within condensed-phase explosives arising from the co-existence of a reactive carrier mixture of miscible materials, and several material interfaces due to the presence of immiscible impurities such as particles or cavities. The dynamic and thermodynamic evolution of the explosive is communicated to one or more inert confiners through their shared interfaces, which may undergo severe topological change. We also wish to consider elastic and plastic structural response of the confiners, rather than make a hydrodynamic assumption for their behaviour. Recently developed methodologies meet these requirements by means of the simultaneous solution of appropriate systems of equations for the behaviour of the condensed-phase explosive and the elastoplastic response of the confiners. In the present work, we employ a mathematical model proposed by Peshkov and Romenski, which unifies fluid and solid mechanics by means of generalising the concept of distortion tensors beyond solids. We amalgamate this model with a single system of partial differential equations (PDEs) which meets the requirement of co- existing miscible and immiscible explosive mixtures. We present the mathematical derivation of our unified model and construct appropriate algorithms for its solution. The model is extensively verified and validated against exact numerical or analytical solutions and available experimental results. To enable the application of the model to a wider range of problems, we consider two further extensions. The first addresses the extension to multiple inert or reactive materials and its assessment on realistic scenarios like the mechanical sensitisation of liquid explosives. The second is concerned with the use of hyperbolic thermal impulse equations to model the conduction of heat across material interfaces. This is assessed in the scenario of thermal-induced ignition and transition to detonation in explosives. Results of this work indicate that the developed formulation provides a powerful alternative to existing combustion models, able to seamlessly account for the complex and highly non-linear multi-material interactions present in combustion applications.

Submesoscale fronts with large horizontal density gradients and O(1) Rossby numbers are common in the upper ocean. These fronts are associated with large vertical transport and are hotspots for biological activity. Submesoscale fronts are susceptible to symmetric instability — a form of convective–inertial instability which occurs when the potential vorticity is of opposite sign to the Coriolis parameter. Symmetric instability is characterised by growing slantwise convection cells nearly aligned with isopycnals and which encourage vertical transport of important biogeochemical tracers in addition to geostrophic momentum. This momentum transport destabilises the balanced thermal wind and can prompt geostrophic adjustment and re-stratification which often leaves remnant inertial oscillations. This thesis sets out to model the impacts of symmetric instability on the structure, evolution, and equilibration of the broad range of submesoscale fronts. We develop a theory for the linear growth and weakly-nonlinear saturation of symmetric instability in the Eady model. This idealised front configuration is motivated by nearly-uniform symmetrically-unstable frontal zones observed during the SUNRISE field campaign in the Gulf of Mexico. Both the fraction of the balanced thermal wind mixed down by symmetric instability and the primary source of energy are strongly dependent on the front strength, defined as the ratio of the horizontal buoyancy gradient to the square of the Coriolis frequency. Strong fronts with steep isopycnals develop a flavour of symmetric instability we call 'slantwise inertial instability' by extracting kinetic energy from the background flow and rapidly mixing down the thermal wind profile. In contrast, weak fronts extract more potential energy from the background density profile, which results in 'slantwise convection.' Using a set of direct numerical simulations, we further investigate the non-linear consequences of these flavours of symmetric instability together with the effect of lateral constraints imposed on the growing modes within finite-width fronts by varying the balanced Rossby number. While weak fronts develop narrow frontlets and excite small-amplitude vertically-sheared inertial oscillations, stronger fronts generate large inertial oscillations and produce bore-like gravity currents that propagate along the top and bottom boundaries. Furthermore, fronts with a super-critical balanced Rossby number equilibrate to a nearly self-similar profile dependent only on the deformation radius, but for small enough Rossby number, self-similar frontlets form and sub-divide the frontal region. We describe each of these mechanisms and energy pathways as the front evolves towards the final adjusted state. These emergent front properties are incorporated into a scaling model framework to describe the ultimate state of the equilibrated front, and broader implications of these results are discussed in the context of current parameterisations of symmetric instability affecting the upper ocean mixed layer and ultimately climate & earth system models.

Climate change has become a major cause for concern over the last 20 years, with the passenger vehicle being a major contributor to greenhouse gas emissions. This paper looks to address what policy decisions and what solutions can be found in order to reduce consumer grade passenger vehicle emissions in a manner that is equitable. In order to answer this problem, a cost benefit analysis was conducted on four policy solution archetypes which were identified through research. When analyzing this problem, it was important to consider the vehicle market itself and identify areas in which certain policy decisions might unfairly support different groups, and how to avoid that. STS research will be conducted by collecting information gathered from other researchers on the various topics at hand within the paper, and synthesizing these findings in order to determine what appropriate solutions might look like. In order to analyze these findings in a fair and overarching manner Utilitarian Ethics was used as a lens. It is likely that current environmental policy decisions unfairly distribute aid and tax incentives to middle to upper middle-class households, which needs to be addressed. Through the research done through the capstone project and the research paper it can be found that current passenger vehicles have numerous technologies which can be utilized in order to reduce the auto industries carbon footprint, primarily by increasing fuel economy. These technologies can be implemented equitably by providing incentive to install new emissions control technology onto preexisting vehicles, allowing lower income households to benefit from emissions control legislation.

My Mechanical Engineering capstone project focused on optimizing the intake system of the University of Virginia’s (UVA) 2023 Formula Society of Automotive Engineers (FSAE) vehicle intended to compete in the Formula SAE competition in Brooklyn, Michigan in May 2023. The intake system includes three main components: Restrictor, Plenum, and Runners. Goals included decreasing the weight of the system, increasing engine horsepower, and improving fuel efficiency. My capstone group went through design constraint screening and scoring over 12 potential intake designs which were completed in the first half of the Fall 2022 semester before focusing on one design. This is UVA’s FSAE team’s third year of competition and improving the functionality of the intake system can help propel the team to a higher overall ranking at the Michigan competition. My capstone group went through extensive research and development of the intake system in the Fall 2022 semester while manufacturing components in the Spring 2023 semester. In the Fall, multiple designs of each component were created on Fusion 360 and went through numerous computation fluids dynamics (CFD) and vibrational analysis simulations to adjust each part’s designs and wall thicknesses. 3D-printers and a computer numerical control (CNC) milling machine were used to manufacture the intake components. This vehicle runs on a 600 cubic centimeter (cc) motorcycle internal combustion engine (ICE) and the UVA team is hoping to transition to an electric Formula SAE car within the next few years. It is important to consider the impact that ICE vehicles and the use of fossil fuels have on the environment. Switching to an electric vehicle will have a positive impact on the environment in addition to giving UVA students an opportunity to enter the workforce with electric vehicle experience. My STS research discusses the need to transition away from a majority fossil fuel source of energy and to nuclear which is much cleaner and sustainable for the environment. Additionally, my research discusses the need for accountability in nuclear disasters. Actor-network-theory (ANT) is used to explore the relationships between the various people and objects involved in producing, regulating, and obtaining nuclear energy. The social construction of technology (SCOT) also explores the technology that safeguards nuclear energy. By exploring the impacts of the Chernobyl nuclear disaster of 1986, the actions of the Soviet Union can be shown to have negatively impacted residents in the area. I expect to discuss the flaws in the reaction to the disaster by the Soviets and how the entire world was needed to help impacted residents. My capstone project and STS research have similar themes of positively impacting the environment and transitioning to more sustainable energy sources: electricity for cars and nuclear for power.

This research aims to address the technical and social aspects to consider when transitioning from an Internal-Combustion Engine (ICE) vehicle to an Electric vehicle (EV). The findings from this paper are intended to serve as proving grounds for the Virginia Motorsports Formula SAE Team as they begin their transition from the ICE to EV competition. The technical project outlines an optimal design structure to follow when developing a new subsystem from scratch. It utilizes methods such as a design matrix, mathematical analysis, advanced simulation, and thoughtful choices backed by engineering science to define the steps to take to design, quantify, manufacture, and test a system from concept to production. The technical aspects are extremely important to consider when understanding how to build a brand-new system from the ground up; however, there are social aspects that are equally significant in ensuring a seamless transition from ICE to EV for the Formula SAE team. It is important to understand how certain social factors, such as competition and economy, inform and bias certain technical decisions, which could lead to the success or the demise of the transition. Actor-Network Theory (ANT) will be utilized to understand the development of certain technical and social actors, and how they interact with one another to stabilize and destabilize the network. Demonstrating an understanding of how the social actors can limit the technical aspects in the scope of the transition from ICE to EV is important to ensure a successful network. A case study of the development and eventual downfall of the 2011 Ford Focus Electric will be analyzed to understand how the associated actor-network was destabilized due to the failures in gaining a complete understanding of the social impacts on the vehicle. The goal of this case-study analysis is to gain a deeper understanding of what aspects were important to the company, in this case Ford, when they were taking their first step into the world of electric vehicles. The Ford Focus Electric had successful elements within the network that aided in generating and establishing it; however, it was ultimately the lack of understanding in the interaction between the social and technical actors that caused the network to destabilize. The capstone research creates an optimized technical framework to follow when developing a new system, while the STS research aims to insight an overall understanding of the limitation of technical decisions because of social aspects. In concert, they both aim to provide sociotechnical findings that will aid the Virginia Motorsports Formula SAE Team to undertake a successful transition from ICE to EV.

IntroductionThoracic endovascular aortic repair (TEVAR) of the arch is challenging given its complex geometry and the involvement of supra-aortic arteries. Different branched endografts have been designed for use in this region, but their haemodynamic performance and the risk for post-intervention complications are not yet clear. This study aims to examine aortic haemodynamics and biomechanical conditions following TVAR treatment of an aortic arch aneurysm with a two-component single-branched endograft.MethodsComputational fluid dynamics and finite element analysis were applied to a patient-specific case at different stages: pre-intervention, post-intervention and follow-up. Physiologically accurate boundary conditions were used based on available clinical information.ResultsComputational results obtained from the post-intervention model confirmed technical success of the procedure in restoring normal flow to the arch. Simulations of the follow-up model, where boundary conditions were modified to reflect change in supra-aortic vessel perfusion observed on the follow-up scan, predicted normal flow patterns but high levels of wall stress (up to 1.3M MPa) and increased displacement forces in regions at risk of compromising device stability. This might have contributed to the suspected endoleaks or device migration identified at the final follow up.DiscussionOur study demonstrated that detailed haemodynamic and biomechanical analysis can help identify possible causes for post-TEVAR complications in a patient-specific setting. Further refinement and validation of the computational workflow will allow personalised assessment to aid in surgical planning and clinical decision making.