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Today's world witnesses an unprecedented augmentation in energy consumption which has tipped the balance of attention toward the renewable energies, especially solar energy as the most promising type. With recent developments in the field of solar heating units, evacuated tube solar units have played a prominent role in solar energy absorption process in recent years due to the existence of a vacuum envelope in the structure of the tubes. Following this, a three-dimensional transient numerical study has been carried out by employing computational fluid dynamics aimed to appraise the water flow, natural circulation process and convective rate inside the evacuated tube along with a storage tank. A comparison has been made using water and CuO/H2O nanomaterial as the operate fluid for the purpose of evaluating the efficacy of nanofluid on the functionality of the system. The results in the form of velocity distribution, temperature and velocity contours served as an array of reasons on serviceability of CuO nanoparticles in the given application. This is evidenced by the natural circulation rate and heat transfer sustaining more desirable magnitudes, while observing an increase in the average temperatures of the tube and tank, respectively. Implementation of CuO/water over plain water has been reasserted categorically and thus justified. [ABSTRACT FROM AUTHOR]

Due to the anatomical complexity of the aortic arch for the development of stent-grafts for total repair, this region remains without a validated and routinely used endovascular option. In this work, a modular stent-graft for aneurysms that covers all aortic arch zones, proposed by us and previously structurally evaluated, was evaluated from the point of view of haemodynamics using fluid-structural numerical simulations. Blood was assumed to be non-Newtonian shear-thinning using the Carreau model, and the arterial wall was assumed to be anisotropic hyperelastic using the Holzapfel model. Nitinol and expanded polytetrafluoroethylene (PTFE-e) were used as materials for the stents and the graft, respectively. Nitinol was modelled as a superelastic material with shape memory by the Auricchio model, and PTFE-e was modelled as an isotropic linear elastic material. To validate the numerical model, a silicone model representative of the aneurysmal aorta was subjected to tests on an experimental bench representative of the circulatory system. The numerical results showed that the stent-graft restored flow behaviour, making it less oscillatory, but increasing the strain rate, turbulence kinetic energy, and viscosity compared to the pathological case. Taking the mean of the entire cycle, the increase in turbulence kinetic energy was 198.82% in the brachiocephalic trunk, 144.63% in the left common carotid artery and 284.03% in the left subclavian artery after stent-graft implantation. Based on wall shear stress parameters, it was possible to identify that the internal branches of the stent-graft and the stent-graft fixation sites in the artery were the most favourable regions for the deposition and accumulation of thrombus. In these regions, the oscillating shear index reached the maximum value of 0.5 and the time-averaged wall shear stress was close to zero, which led the relative residence time to reach values above 15 Pa−1. The stent-graft was able to preserve flow in the supra-aortic branches. [ABSTRACT FROM AUTHOR]

Dielectric oil has been recently used in wire electrical discharge machining (wire EDM) for achieving high-precision machining. However, the influence of dielectric oil properties on wire EDM characteristics has not been clarified sufficiently. This study fundamentally investigated the influence of dielectric oil viscosity on wire EDM characteristics. In this study, three types of dielectric oil differing only in viscosity were prepared and examined. Linear cutting experiment results showed that the removal rate and the machined surface roughness increase with dielectric oil viscosity. Then, the influence of viscosity on crater removal volume was investigated to discuss the cause of the change in removal rate, and it was found that crater removal volume increases with the viscosity. Furthermore, CFD (computational fluid dynamics) analysis results and discharge observation results showed that the debris exclusion becomes worse in higher viscosity oil, and the discharge concentration occurs frequently, resulting in the deterioration in machined surface roughness. Next, the difference in machining accuracy with dielectric oil viscosity was investigated. It was found that the corner shape accuracy deteriorates with the increase of viscosity while the machined surface waviness and straightness improve slightly. Structural analysis results showed that wire deflection increases with viscosity, resulting in the deterioration in corner shape accuracy. On the other hand, high-speed observation of wire vibration was carried out, and it was found that the wire vibration decreases in the case of higher viscosity, which leads to the improvement in machined surface waviness and straightness. [ABSTRACT FROM AUTHOR]

This study investigates, for the first time ever, the suffusion on gap‐graded granular soils under torsional shear conditions from a microscopic perspective. A numerical model of the hollow cylinder torsional shear test (HCTST) using the discrete element method (DEM) is first developed, where an algorithm for simulating the real inner and outer rubber membranes of the hollow cylinder apparatus (HCA) is introduced. After the validation, the computational fluid dynamics (CFD) approach is introduced for the coupling between the particle and fluid phases. Then, a series of the coupled CFD‐DEM suffusion simulations considering the rotation of the major principal stress axis (α) and intermediate principal stress ratio (b) are conducted. It is found that more fine particles are eroded in cases having smaller α and b, and the clogging phenomenon in the middle zones becomes more significant as both α and b increase. From the microscopic perspective, the specimens whose contact anisotropy principal direction is close to the fluid direction will lose more fines, and the anisotropy magnitude also plays an important role. In addition, the differences in structure and vertical connectivity of the pores in HCTST samples under various complex loading conditions cause fine particles to have different migration paths, further resulting in different fines mass loss. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to evaluate the changes of upper airway ventilation function after molar distalization with aligners in adult patients by computational fluid dynamic simulation. Materials and methods: A total of 15 subjects were included (3 males and 12 females, with an average age of 20.00 ± 0.50 years) who required en masse distal movement of the whole dentition using Invisalign aligners. The software Mimics 19.0 was used to reconstruct the upper airway based on their CBCT images and measure the minimum cross-sectional area and volume before and after treatment. Then the upper airway flow during inspirations was simulated and evaluated using Ansys software. At last, the morphologic and hydrodynamic parameters before and after treatment were compared using paired T-test. Results: For morphological evaluation, the volume changes of velopharynx, glossopharynx and hypopharynx volume revealed no statistically significance after treatment compared to the data before treatment, the minimum cross section of upper airway decreased significantly. For hydrodynamics parameters, the minimum pressure, maximum shear force, velopharynx and glossopharynx pressure drop increased 50.2 Pa, 0.66 Pa, 5.78 Pa and 5.32 Pa respectively. At last, the correlation analysis between CFD data and MCA is of no statistical significance. Conclusion: Non-extraction molar distalization using invisible aligners and mini-screws may lead to adverse changes in upper airway fluid dynamics, potentially increasing the risk of pharyngeal collapse. Clinical relevance: The combination of invisible appliances with anchorage implants for the distalization of maxillary and/or mandibular teeth has emerged as a prevalent orthodontic technique. Clinicians should consider the potential impact on respiratory function when contemplating such treatment for patients with pre-existing respiratory conditions or those at a higher risk of ventilation issues. [ABSTRACT FROM AUTHOR]

This article explores the utilization of a synthetic jet as an approach to cool microelectronic devices, addressing their thermal management needs. The study includes both experimental measurements and numerical simulations to gain a comprehensive understanding of the heat transfer characteristics and fluid flow patterns generated by the synthetic jet actuator. The average Nusselt number (Nu) of the synthetic jet impinging flow with the dimensionless separation distances of the orifice to the heated surface (H/D) is investigated at different Reynolds numbers. A dynamic mesh scheme is employed in performing the simulations of the fluid domain to showcase the diaphragm's vibration and its deformation over time. The velocity profiles exhibit that the synthetic jet flow prompts the formation of two countervortices during every vibrating cycle of the diaphragm. The experimental results align closely with the predicted outcomes, indicating that the synthetic jet significantly enhances heat transfer by 3.1 times relative to the natural convection in the case of (H/D = 8.4) across different Reynolds numbers while maintaining low power consumption, a compact size, and a noise‐free operation. [ABSTRACT FROM AUTHOR]

This study optimizes the main parameters of the cold‐side heat exchanger (CHE) longitudinal fin, including fin quantity (Nf), fin thickness (Tf), and fin height (Hf), to enhance the performance of motorcycle exhaust thermoelectric generator units (TGUs) utilizing the computational fluid dynamics approach. The investigation shows that these parameters significantly affect the dissipation area of the CHE heat and the outside air velocity distribution in fin gaps, resulting in the fluctuation of TGU output power. The output power increases with respect to Hf; nevertheless, it first increases as Nf and Tf increase but decreases dramatically when Nf or Tf becomes too large. Besides, Hf significantly affects output power, and its impact is almost independent of Tf and Nf, and vice versa; meanwhile, Tf and Nf have a strong relation. This study proposes two Hf of 40 and 60 mm along with the optimal Tf of 1 mm and Nf of 29, providing significantly high output power, low weight, and compact size for TGU. This work contributes insight into the effect of CHE parameters on the TGU performance, and it is a crucial case study for selecting suitable heat sink parameters for TGU, considering practical requirements and conditions. [ABSTRACT FROM AUTHOR]

Exposure to cement dust can cause respiratory problems and structural changes in respiratory airways. Computed tomography (CT) has shown that the airways of individuals with cement dust exposure (CDE) exhibit narrowing, wall thickening, and altered bifurcation angles. This study aimed to investigate the differences in airflow structure and particle transport between individuals with CDE and those with non-cement dust exposure (NCDE). To this end, computational fluid dynamics and Lagrangian particle tracking specialized for the respiratory system were employed, and two particle models representing cement dust and microdust were established. To construct three-dimensional airway models, CT images were obtained from four subjects with CDE and four with NCDE. Physiologically accurate small airways were virtually established to explore the flow structures in CT-unresolved regions. Subjects with NCDE showed higher wall shear stress and pressure drops in the lower lobes than in the upper lobes of the lungs. Conversely, subjects with CDE showed higher wall shear stress and pressure drops in the upper lobes than in the lower lobes. Furthermore, the narrowed airways of subjects with CDE caused strong dissipation, turbulence, and secondary flows, exacerbating the deposition of cement dust in the corresponding regions. However, the microdust model showed consistently low deposition fractions in all airway models, indicating deep penetration into the lungs, regardless of respiratory health. Thus, CDE alters the airway structure and parenchymal function, which further affects fluid dynamics and particle deposition characteristics. This study elucidates the fluid flow and particle deposition patterns within airways narrowed by CDE. Copyright © 2024 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

In this study, the hydrodynamics and thermal behavior in the crossflow of air passing over hybrid tubes in the staggered configuration were numerically investigated. CFD (Computational Fluid Dynamics) study were conducted with the help of the ANSYS Fluent program. In the study, 12 different tube bundle models were created with a combination of circular and wing-shaped tubes. The wing-shaped tubes were placed in the tube bundle at different attack angles (θ: 0° and 180°). Reynolds numbers in the range of 4000 ≤ Re ≤ 12,000 were used. To observe the effects of hybrid tubes and Reynolds numbers on thermal and flow fields, velocity, pressure, and temperature contours were acquired. According to the findings, Nusselt number (Nu) and performance criteria (PC) increased, and friction factor (f) decreased with increasing Re for all tube bundle models. The friction factor of hybrid tube bundles was higher than wing-shaped tube bundles but considerably lower than circular tube bundles. Among the hybrid models, the best heat transfer was obtained in Model 6, the lowest friction factor in Model 11, and the best PC in Model 4. Also, three different stacked ensemble models were created to predict Nu, f, and PC values for CFD analysis. These models are the ensemble of XGBoosts, the ensemble of DNNs, and the ensemble of DNN, XGBoost, and RF. This study revealed that ensemble of XGBoosts is more beneficial than the other in the CFD analysis. [ABSTRACT FROM AUTHOR]

Coronary arteries serve a crucial purpose in the circulatory system as they supply blood to the human heart, a highly oxidative organ. As the blood flows through these arteries, the constituents of blood such as proteins and fatty acid molecules may start depositing on the arterial lining. These depositions narrow down the arteries and obstruct the blood flow to the heart. This phenomenon is termed as atherosclerosis, responsible for coronary artery disease, a leading cause of death globally. The progression of disease is affected by coronary hemodynamics which strongly depends on the geometrical complexities such as branching and tapering, and the associated parameters such as curvature and tortuosity. These geometrical parameters vary across the population and are affected by factors such as dietary habits, gender, lifestyle and genetics. Technological advancements in the past few decades have resulted in emergence of patient-specific computational fluid dynamics (CFD) modelling as an important tool in cardiovascular engineering and technology. Patient-specific CFD modelling utilises the clinically obtained patient-specific geometrical and boundary condition data to model the flow and gain an insight in the detailed hemodynamic behaviour, calculate different parameters which can be used as biomarkers and assess different treatment options. In this article, we provide a brief overview of the human coronary circulation and typical steps involved in patient-specific modelling. Further, the studies on patient-specific coronary hemodynamics are extensively reviewed and a perspective on future trends is provided. We believe that the article will serve as a beginner's guide for the researchers working in this emerging area. [ABSTRACT FROM AUTHOR]

The novel coronavirus (SARS-CoV-2) outbreak has spread worldwide, and the World Health Organization (WHO) declared a global pandemic in March 2020. The transmission mechanism of SARS-CoV-2 in indoor environments has begun to be investigated in all aspects. In this regard, many numerical studies on social distancing and the protection of surgical masks against infection risk have neglected the evaporation of the particles. Meanwhile, a 1.83 m (6 feet) social distancing rule has been recommended to reduce the infection risk. However, it should be noted that most of the studies were conducted in static air conditions. Air movement in indoor environments is chaotic, and it is not easy to track all droplets in a ventilated room experimentally. Computational Fluid Dynamics (CFD) enables the tracking of all particles in a ventilated environment. This study numerically investigated the airborne transmission of infectious droplets in a hospital examination room cooled by a split-type air conditioner with the CFD method. Different inlet velocities (1, 2, 3 m/s) were considered and investigated separately. Besides, the hospital examination room is a model of one of the Bursa Uludag University Hospital examination rooms. The patient, doctor, and some furniture are modeled in the room. Particle diameters considered ranged from 2 to 2000 μm. The evaporation of the droplets is not neglected, and the predictions of particle tracks are shown. As a result, locations with a high infection risk were identified, and the findings that could guide the design/redesign of the hospital examination rooms were evaluated. [ABSTRACT FROM AUTHOR]

In this paper, the Edinburgh Elasto-Plastic Adhesion (EEPA) model is used to characterize discrete-element particles. Based on the coupling technology of the computational fluid dynamics (CFD)-discrete-element method (DEM), the Euler–Lagrange interface is used to realize the solid–liquid coupling of muck and slurry in order to establish the numerical analysis model of jet crushing mud cake, and the correctness of the model is verified by jet testing. In order to investigate the crushing characteristics of mud cake under hydrodynamic action, further research is conducted on the crushing process of mud cake under different amounts of adhesion, compaction strength, and adhesion strength by jet impact. The mechanism of jet scouring mud cake is revealed by the force of fluid on mud cake particles, the form of mud cake breaking, and its breaking effect. The research results show that when the change in the amount of mud cake is proportional to the change in the contact area of the cutterhead, the crushing amount of the mud cake by the jet remains unchanged at first and then decreases. Whether the mud cake can be broken under different compaction strengths depends on its shear strength and its elastic–plastic state. The adhesion strength of particles greatly influences whether the mud cake can be broken. When the surface energy of the adhesion strength parameter increases to 1,200 J/m3, the jet force is not sufficient to break the mud cake. The research in this paper can provide new ideas and methods to guide the design of the scouring system of the anti-mud-cake cutterhead. [ABSTRACT FROM AUTHOR]

Solid fluidization is a promising method for the development of marine hydrate resources. The back pressure makes it difficult to backfill the separated sand to the well bottom, resulting in a decrease in separation performance and serious failure of hydrocyclone. This study is intended to study the effect of underflow diameter on the performance of the hydrocyclone by computational fluid dynamics method. The results show that with the increase of back pressure, the split ratio basically decreases linearly, and the LAVV gradually increases. Under the same back pressure, the underflow diameter is larger, the pressure drop is smaller. No matter how large the underflow diameter is, the hydrocyclone may fail once back pressure exceeds 60 kPa. Under the same back pressure, the larger the underflow diameter is, the higher the desanding efficiency is, while the purification efficiency is opposite. When back pressure exceeds 60 kPa, the desanding efficiency drops sharply, while the purification efficiency remains basically unchanged. This study is applicable to downhole in-situ separation for solid fluidization of marine hydrate. The purpose of this study is to guide the structure design of hydrocyclone and the optimization of hydrate production process parameters. [ABSTRACT FROM AUTHOR]

A low-order physics-based model to simulate the unsteady flow response to airfoils undergoing large-amplitude variations of the camber is presented in this paper. Potential-flow theory adapted for unsteady airfoils and numerical methods using discrete-vortex elements are combined to obtain rapid predictions of flow behavior and force evolution. To elude the inherent restriction of thin-airfoil theory to small flow disturbances, a time-varying chord line is proposed in this work over which to satisfy the appropriate boundary condition, enabling large deformations of the camber line to be modeled. Computational fluid dynamics simulations are performed to assess the accuracy of the low-order model for a wide range of dynamic trailing-edge flap deflections. By allowing the chord line to rotate with trailing-edge deflections, aerodynamic loads predictions are greatly enhanced as compared to the classical approach where the chord line is fixed. This is especially evident for large-amplitude deformations. [ABSTRACT FROM AUTHOR]

This study explored the aerodynamic aspects of the Hyundai Universe Express Noble bus, a common passenger bus model in Bangladesh, and proposed modifications to improve its performance. The airflow around the bus was analyzed using Computational Fluid Dynamics (CFD) simulations. Consequently, areas of high drag and turbulence were identified. These results led to the redesign and testing of several shape modifications for the bus, including adjustments to the roof spoiler, side mirrors, and front grille. After finding the bus model with the lowest drag coefficient, that model is further analyzed to find the aerodynamic effects of side windows on a bus and their impact on fuel efficiency. The aim is to determine how much side windows significantly affect fuel efficiency. The aerodynamic effect with windows open and closed is also evaluated after identifying an appropriate model. Model 1.2 uses 7.72% less fuel than base Model 1.0. Model 1.2 with windows uses 2.5% more fuel than Model 1.2. The study also evaluates the fuel cost per 500 km for all models suggesting that non-ac buses with side windows consume slightly more fuel than AC buses. Changing the bus shape to Model 1.2 will reduce the drag coefficient by 8.67% and fuel consumption by 7.72%. The study offers insights into reducing drag force, minimizing air resistance, enhancing exterior styling, and improving vehicle stability. Furthermore, these findings have practical implications for the transportation industry as they demonstrate the potential for improving the efficiency and sustainability of large vehicles through aerodynamic design. [ABSTRACT FROM AUTHOR]

The current study analyzed the piezoelectrically driven mechanism responsible for generating force in both rectangular and hummingbird wings, which mimicked the flapping motion of the micro air vehicles, utilizing a combination of numerical simulation and experimental approaches. Digital image correlation technology was employed within the experimental setup to capture the dynamic deformation pattern of the flapping wing, yielding dynamic deformation data. This dataset was subsequently integrated into the computational fluid dynamics (CFD) simulation software to explain the aeroelastic effects. In this way, the dynamic deformation data played a crucial role in computing inertial forces regarding wing flexibility. In addition, temporal force variations generated by the flapping wing were measured using a load cell. The numerical results provided a full understanding of the flapping wing's unsteady aerodynamics, with an emphasis on vortex formations and pressure distribution. We thoroughly examined the force produced by the piezo-actuated flapping wing system. This analysis was then rigorously compared with the data obtained from the load cell measurements. Our primary emphasis was on the vertical forces along the z-axis. Moreover, a thorough comparison of the combined CFD and experimental data inertial results revealed an overall agreement in the total forces from the load cell. [ABSTRACT FROM AUTHOR]

Administering fluids and drugs intravenously is crucial in caring for vulnerable patient cohorts such as critically ill patients as well as neonatal and paediatrics patient populations. Studies have revealed severe contamination of infusion solution that could be avoided by utilizing in-line filters. The filtration performance consequently depends on the geometry of the filter housing. The purpose of our numerical study was to analyse the flow situation in filter housings depending on the geometry (diameter of the filter housing and distance between entrance and membrane). We compared the flow of two circular filter system with different housing width (D = 25 mm; L = 1.5 mm/3.0 mm) by means of computational fluid dynamics (CFD). The filter membrane was modelled by a porous jump condition. Both filter systems showed a highly reduced inflow on the membrane compared to the velocity in the Luer Lock ports. The wide filter housing facilitates a more homogenous inflow on the membrane (>92% of the membrane area is applied within a range of 5% of the mean velocity) compared to the narrow filter housing. Despite that difference both filter housings induced a well distributed flow through the filter membrane. However, for large filter systems (>50 mm diameter) the design of the filter housing could play a crucial role in optimising filter performance and therefore CFD should be considered. [ABSTRACT FROM AUTHOR]

Oxygenators are a lifesaving technology used for blood oxygenation and decarboxylation in case of acute respiratory failure, chronic lung disease, and during open-heart surgery. Devices typically consist of a bundle of thousands of fibre membranes in a housing, with gas flowing inside the fibres and blood flowing in the opposite direction outside the fibres. Both ends of the fibre-membranes are fixed with an adhesive to separate gas and blood. The shape of the volume through which the blood flows is determined by the housing of the oxygenator and the internal end surfaces of the fixed ends of the fibre-membrane bundle. The traditional potting process results in a volume shape that is associated with stagnation zones, which are known to promote thrombus formation. In this study, an adapted potting process is proposed which results in a blood compartment with bevelled end faces of the glued bundle parts. Using a numerical study, we have demonstrated that the novel oxygenator design results in optimized flow conditions. [ABSTRACT FROM AUTHOR]

Purpose: Angioplasty with stent placement is a widely used treatment strategy for patients with stenotic blood vessels. However, it is often challenging to predict the outcomes of this procedure for individual patients. Image-based computational fluid dynamics (CFD) is a powerful technique for making these predictions. To perform CFD analysis of a stented vessel, a virtual model of the vessel must first be created. This model is typically made by manipulating two-dimensional contours of the vessel in its pre-stent state to reflect its post-stent shape. However, improper contour-editing can cause invalid geometric artifacts in the resulting mesh that then distort the subsequent CFD predictions. To address this limitation, we have developed a novel shape-editing method that deforms surface meshes of stenosed vessels to create stented models. Methods: Our method uses physics-based simulations via Extended Position Based Dynamics to guide these deformations. We embed an inflating stent inside a vessel and apply collision-generated forces to deform the vessel and expand its cross-section. Results: We demonstrate that this technique is feasible and applicable for a wide range of vascular anatomies, while yielding clinically compatible results. We also illustrate the ability to parametrically vary the stented shape and create models allowing CFD analyses. Conclusion: Our stenting method will help clinicians predict the hemodynamic results of stenting interventions and adapt treatments to achieve target outcomes for patients. It will also enable generation of synthetic data for data-intensive applications, such as machine learning, to support cardiovascular research endeavors. [ABSTRACT FROM AUTHOR]

Purpose: CoRISMA MCS Systems Inc (Hamden CT) is developing an innovative mechanical circulatory support system (CMCS) as a durable therapeutic option for heart failure (HF) patients. The CMCS system is comprised of an axial flow pump, non-contacting hydrodynamic bearings, and integrated DC motor designed to be fully implantable in a left atrial (LA) to aortic (Ao) configuration; this unloading strategy may be particularly beneficial for HF patients with preserved ejection fraction (HFpEF). The small (5.5 cm3), lightweight (20 g), and low power (5–7 W) device design should allow for a less invasive off-pump implant. We present early-stage engineering development and testing of the prototype CoRISMA pumps. Methods: Computational fluid dynamics (CFD) modeling was performed to evaluate flow and shear in two impeller (3 blades, 0.5 mm thickness, 8.9 mm diameter, 0.15 mm gap, polished titanium) and diffusor (5 blades, polished titanium) candidate designs. Test apparatuses were custom built to expedite development of the impeller/diffuser designs and iteratively refine the CFD models. Two candidate impeller/diffusor designs were fabricated and tested in each of the two test apparatuses (n = 4 impeller/diffuser + test fixture configurations) in static mock flow loops (hydrodynamic H-Q curves, 3.5 cP glycerol solution at 37 °C), and in dynamic mock flow loops (hemodynamics, 3.5 cP glycerol solution at 37 °C) tuned to HF conditions (mean aortic pressure 50 mmHg, central venous pressure 15 mmHg, aortic flow 3.0 L/min, and heart rate 80 bpm). Results: CFD predicted flows of 4.56 L/min and 4.82 L/min at 100 mmHg for impellers/diffusers 1 and 2, respectively. Impeller 2 required less torque to generate a 6% increase in fluidic flow, and the diffuser had a larger area of high pressure, indicative of lower friction, which likely contributed to the increased efficiency. Experimental testing for all four configurations in the static and dynamic mock loops met performance metrics as evidenced by generating 4.0–4.5 L/min flow against 70–76 mmHg pressure at 25,000 rpm and restoring hemodynamics in the dynamic mock flow loop (MAP = 80 mmHg, CVP = 0 mmHg, total flow = 5.5 L/min) from baseline simulated HF test conditions. Conclusion: These results demonstrate proof-of-concept of the early engineering design and performance of the prototype CoRISMA pumps. Engineering specifications, challenges observed, and proposed solutions for the next design iteration were identified for the continued development of an effective, reliable, and safe LA-to-Ao CMCS system for HF patients. Current design plans are underway for incorporating a wireless energy transfer system for communication and power, eliminating the need for and complications associated with an external driveline, to achieve a fully-implantable system. [ABSTRACT FROM AUTHOR]

Purpose: The Wall Shear Stress (WSS) is the component tangential to the boundary of the normal stress tensor in an incompressible fluid, and it has been recognized as a quantity of primary importance in predicting possible adverse events in cardiovascular diseases, in general, and in coronary diseases, in particular. The quantification of the WSS in patient-specific settings can be achieved by performing a Computational Fluid Dynamics (CFD) analysis based on patient geometry, or it can be retrieved by a numerical approximation based on blood flow velocity data, e.g., ultrasound (US) Doppler measurements. This paper presents a novel method for WSS quantification from 2D vector Doppler measurements. Methods: Images were obtained through unfocused plane waves and transverse oscillation to acquire both in-plane velocity components. These velocity components were processed using pseudo-spectral differentiation techniques based on Fourier approximations of the derivatives to compute the WSS. Results: Our Pseudo-Spectral Method (PSM) is tested in two vessel phantoms, straight and stenotic, where a steady flow of 15 mL/min is applied. The method is successfully validated against CFD simulations and compared against current techniques based on the assumption of a parabolic velocity profile. The PSM accurately detected Wall Shear Stress (WSS) variations in geometries differing from straight cylinders, and is less sensitive to measurement noise. In particular, when using synthetic data (noise free, e.g., generated by CFD) on cylindrical geometries, the Poiseuille-based methods and PSM have comparable accuracy; on the contrary, when using the data retrieved from US measures, the average error of the WSS obtained with the PSM turned out to be 3 to 9 times smaller than that obtained by state-of-the-art methods. Conclusion: The pseudo-spectral approach allows controlling the approximation errors in the presence of noisy data. This gives a more accurate alternative to the present standard and a less computationally expensive choice compared to CFD, which also requires high-quality data to reconstruct the vessel geometry. [ABSTRACT FROM AUTHOR]

A numerical study was performed to analyze the particle deposition of a cold spray process for the preparation of nickel electrocatalysts used in the Hydrogen Evolution Reaction (HER). The study focused on the creation of fin-shaped geometries with an optimal porosity on the electrode surface using a mask located between the nozzle exit and the substrate. Computational Fluid Dynamics (CFD) was performed on a three-dimensional high-pressure nozzle, with nickel powder used as the injection feedstock. The behavior of particles was effectively modeled through a two-way coupled Eulerian–Lagrangian approach. As per the parametric study, four masks of varying wire thicknesses and opening sizes were investigated. The masks were placed at 4 mm increments from the nozzle exit, with the substrate placed at standoff distances (SODs) of 10 mm and 20 mm. To capture the effects of the gas inlet operating conditions, two different nozzle inlet conditions were analyzed (2 MPa and 400 °C, 4 MPa and 800 °C). It was found that the nozzle inlet operating condition had the most significant impact, as it relates to the particle velocity and powder deposition. The high-pressure operating condition resulted in a deposition efficiency (DE) greater than 99.9% for all the test cases, with nearly all the impacted particles depositing on the substrate. For the medium-pressure operating condition, the DE increased linearly as the mask SOD was increased, due to the increase in the particle velocity upon impact. [ABSTRACT FROM AUTHOR]

This paper focuses on a typical pressure-controlled slide valve, utilizing momentum analysis and computational fluid dynamics to simulate and analyze the asymmetry of steady flow force curves under bidirectional throttling patterns. The entropy production theory is employed to reveal the causes of nonlinearity in the steady flow force of an inlet throttling slide valve. Based on flow field analysis, a flow force compensation scheme is proposed by adding a guiding shoulder and matching it with a suitably sized inner annular cavity. The study reveals that fluid momentum at the non-throttling valve port is the primary cause of the bidirectional throttling flow force difference, and under large-opening inlet throttling conditions, it may reverse the direction of the flow force. Vortex separation caused by turbulent pulsations is one of the intrinsic reasons for the nonlinearity of steady flow force. [ABSTRACT FROM AUTHOR]

The Crabster CR200 is an underwater walking robot inspired by crabs and lobsters, designed for precise seabed inspection and manipulation. It maintains stability and position on the seafloor, even in strong currents, by adjusting its posture through six legs, each with four degrees of freedom. The key advantage of the CR200 lies in its ability to resist drifting in strong currents by adapting its posture to maintain its position on the seafloor. However, information is still lacking on which specific posture generates the maximum downforce to ensure optimal stability in the presence of currents and the seabed. This study aims to determine the fluid forces acting on the CR200 in various postures using Computational Fluid Dynamics (CFD) and identify the posture that generates the maximum downforce. The posture is defined by two parameters: angle of attack and seafloor clearance, represented by the combination of the robot's pitch angle and distance to the seabed. By varying these parameters, we identified the posture that produces the greatest downforce. Through a series of analyses, we identified two main fluid dynamic principles affecting the downforce on a robot close to the seabed. First, an optimal pitch angle exists that generates the maximum downward lift on the robot's body. Secondly, there is an ideal distance from the seabed that produces maximum suction on the bottom surface, thereby creating a strong Venturi effect. Based on these principles, we determined the optimal robot posture to achieve maximum downforce in strong current conditions. The optimal underwater robot posture identified in this study could be applied to similar robots operating on the seafloor. Furthermore, the methodology adopted in this study for determining the optimal posture can serve as a reference for establishing operational postures for similar underwater robots. [ABSTRACT FROM AUTHOR]

The Joule heat generated by current flow between electrodes in a resistance furnace not only melts and heats the charge but also induces mixing of the molten material. Increased mixing promotes improved chemical and temperature uniformity within the bath. This paper presents a novel approach to effectively optimizing electrode geometry in resistance furnaces. The method relies on a surrogate criterion derived exclusively from an electromagnetic submodel, which governs the process hydrodynamics. This criterion is based on the location of the Joule heat generation center in the bath. Its idea is to lower this center as much as possible while keeping it close to the vertical bath axis. Owing to this, the best conditions for the development of natural convection were obtained. The developed methodology was demonstrated through an application to a two-electrode furnace. The results showed that the influence of forced MHD convection is negligible in this furnace (with a Lorentz force of only about 0.0015 N/kg). The validation of the optimized geometry, derived using solely the electromagnetic submodel, was carried out using a full process model, including time-consuming hydrodynamic calculations. The proposed optimization methodology enabled a 10-fold increase in the average mixing velocity (from 0.0008 to 0.0084 m/s). The main significance of the presented study is the introduction of a surrogate criterion that allows for a multiple reduction in the time of numerical optimization of the mixing intensity in electrode resistance furnaces in comparison to the standard solution based on the flow velocity criterion determined from the hydrodynamic model. [ABSTRACT FROM AUTHOR]

Historical building reuse is aimed at preservation, where buildings are recovered for new uses connected to cultural activities. This paper presents the analysis of the impact of thermo-fluid dynamics due to a 500 kW electrical power transformer installed inside a historical building. The analysis is performed using computational fluid dynamics simulations validated through measurement campaigns carried out during the summer period. High temperatures and wide humidity variations can damage building plasters and cause malfunctions in power equipment. To avoid these situations, two different installation layouts were studied. One consists of the power transformer directly installed in the environment and cooled by an inlet fan, and the other consists of the power transformer being insulated from the external environment by an enclosure connected to a forced ventilation system. The second layout showed better results both inside and outside the transformer enclosure. The maximum indoor condition was about 4.3 °C, with a −7.2% RH and an airflow rate of 1100 m3/h, and the maximum outdoor air condition was 3.3 °C, with a −1.39% RH and a flow rate of 2200 m3/h. However, the temperatures and humidity inside the building and outside the transformer enclosure were almost the same. [ABSTRACT FROM AUTHOR]

A left ventricular assist device (LVAD) supports hemodynamics in heart failure patients. To deepen the understanding of hemodynamic changes and the movement of thrombi in the aorta, we examined three distinct LVAD blood flow rates across two implantation sites using the theory of computational fluid dynamics. Our findings revealed the complex dynamics of blood flow during cardiac systole under various scenarios. We also analyzed thrombi residence time and flow probabilities into aortic branches. Simulation results indicate that thrombi distribution in the aorta is significantly influenced by the location of the LVAD outflow graft and the flow rate. When the LVAD outflow graft is implanted into the ascending aorta, higher flow rates may reduce the risk of cerebral thrombosis. However, lower flow rates may reduce the risk of cerebral thrombosis while it is implanted into the descending aorta. The study may offer valuable insights into the LVAD implantation about the risk of cerebrovascular embolism. [ABSTRACT FROM AUTHOR]

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This study analyzed the hybrid ventilation efficiency of indoor toilet plumes generated post-flushing with various designs. Single-sided natural ventilation and hybrid ventilation were numerically investigated to determine the impact of vent locations commonly found in multistorey buildings. An in-situ experiment was performed to identify the size distribution of the plume with time series. A computational fluid dynamics model based on the Reynolds-averaged naiver-Stokes equations and baseline k-ω turbulence equations was used to predict aerosol pollutant transmission. The aerosol-laden particles receded gradually impacted by the convection of the ambient source. Besides flush volume, temperature and ventilation scenarios were also related to the generation and droplet transmission. The results indicated that the ventilation rates were generally increased with decreased residence time if the turbulence was not suppressed. This study suggested that appropriate ventilation design could significantly reduce the average particle residence time, in which case it could also reduce the rate of virus infection. [ABSTRACT FROM AUTHOR]

Exhaled aerosols can be suspended in the air for long periods, facilitating the transmission of highly infectious respiratory diseases. The risk of exposure to occupants varies due to different usage conditions and driving scenarios of moving vehicles. Therefore, the present study investigates the airborne transmission of contaminants generated by coughing in a moving vehicle and explores the relationship between aerosol dispersion and fluid exchange between the interior and exterior domains of the car under the influence of window opening configurations, seating layouts and driving speeds. The results show that the cross-opening configurations provide a superior contaminant removal efficiency. The effect of seating layout on removal efficiency is significant, although it has a slight effect on air change rate (ACH). The best removal efficiency can be obtained when the passenger sits in the front seat with the right front window opening. Furthermore, the in-cabin ACH is almost linearly correlated with the driving speed. Higher speeds reduce contaminant concentrations faster. However, the risk of driver exposure does not depend solely on ACH, the peak cumulative contaminant concentration and residence time also need to be considered. This study offers data for the prevention and control of respiratory infectious diseases. [ABSTRACT FROM AUTHOR]

Respiratory infectious diseases have affected the health of the elderly. This study investigated the optimization of physical barriers as a low-cost design strategy to reduce the risk of infection in nursing homes for the elderly in Hong Kong, which were significantly affected by the outbreak of COVID-19. First, data on two types of rooms, single and multi-occupancy, were collected from a field investigation of typical local nursing homes. Subsequently, Computational Fluid Dynamics (CFD) simulations were employed to analyse the effects of various barrier heights on the propagation, suspension, deposition and elimination of aerosol particles in these room types, thereby evaluating infection risks. The findings reveal that in single-occupancy rooms, a barrier height of 2.1 m is effective in curtailing the spread of the virus over distances. Conversely, in multi-occupancy rooms, while a 1.8-m barrier is necessary, the rate of particle suspension is considerably higher, necessitating additional ventilation measures. Based on these findings, the study provides quantitative criteria for the implementation of physical barriers as a low-cost physical measure in nursing homes and provides recommendations for the effective prevention of respiratory infectious diseases through design modifications. [ABSTRACT FROM AUTHOR]

Evacuated tube solar collector (ETSC) has gained significant attention due to its high thermal efficiency and ability to harness solar energy more effectively as compared to flat plate solar collector. The present review analyzed the in-depth mechanism of analytical modeling of ETSC, different factors influencing the performance, and applications in drying of Agri-commodities. Evacuated tubes with and without heat pipes are used for air heating purposes. ETSC with tracking and non-tracking, selective coating techniques, and for reducing heat loss during drying operations are reported. The system performance is greatly influenced by the ETSC design, absorber coating, heat transfer fluid, mass flow rate of working fluid, inclination or tilt angle, collector size, and distance between tubes. Moreover, Computational fluid dynamic (CFD) simulations of the various ETSC-based drying systems were compiled to investigate their flow patterns, heat transfer characteristics, and overall system performance. This literature inherently provides the way for the development of evacuated tube-based innovative and sustainable solar dryers in small and industrial scale. [ABSTRACT FROM AUTHOR]

Temperature uniformity is a fundamental parameter for a forced convection oven to guarantee food baking quality. In this study, computational fluid dynamics (CFD) simulation is employed to analyze the air flow and heat transfer within a forced convection oven. Subsequent experimental measurements were conducted to explore the temperature variations inside the oven. The maximum deviation between the numerical simulation results and the experimental data was 2.70%, demonstrating the high accuracy of the simulation model. Based on the established simulation model, we can meticulously investigate the impact of fan structures on the airflow and temperature fields. Carefully designing the fan structure can significantly enhance temperature uniformity across the oven's baking racks, reducing the standard deviation of temperatures on the second and third baking racks from 5.46°C and 6.69°C to 2.26°C and 2.46°C, respectively. This study provides a robust design strategy for forced convection ovens, yielding tangible benefits for practical application and market competitiveness. [ABSTRACT FROM AUTHOR]

Aerodynamic performance of a semi-submerged inlet exposed to a significant amount of boundary layer ingestion is optimized using the open-source flow and adjoint solver SU2. Pressure recovery is taken as the objective function. Mass flow rate and total pressure distortion at the aerodynamic interface plane are also monitored. Optimization is performed in two parts. First, the inlet duct is optimized while keeping the vertical offset and the total duct length fixed, and a limited improvement in performance is observed. Next, the wall surface upstream of the inlet, where the ingested boundary layer develops, is included in the optimization study. It is shown that the shape optimization now provides a boundary layer diverting inlet and a significant improvement is achieved in both pressure recovery and flow distortion. [ABSTRACT FROM AUTHOR]

After certain time of operation, the cross-section of cooling channels in injection molds may decrease due to fouling, i.e. the formation and growth of a layer of sediment on the walls of the channels. This phenomenon can decrease heat transfer or ultimately completely block the flow of coolant in the channel. The build-up of the sediment layer increases the temperature of the mold, which may consequently reduce the quality of the plastic products. In the paper, the pressure drop in a typical cooling channel of an injection mold is investigated, as well as the effect of the sediment layer on the coolant flow in an example channel with a diameter of 10 mm. A novelty is the developed analytical model that allows determining the pressure drop in the case when two perpendicular channels do not intersect centrally due to manufacturing inaccuracies that often happen when drilling long channels in hard materials. The proposed hydraulic model allows for calculation of the coolant pressure drop in real injection molds and can be an alternative to time-consuming CFD simulations. The presented results of measurements and the hydraulic model calculations show that the thickness of the sediment layer in the tested channel of the actual injection mold can be up to 1.7 mm. The hydraulic model proposed in this work allows for the estimation of the thickness of the sediment layer and the identification of places of local increase in the coolant velocity, where self-cleaning of the channels in injection molds may take place. [ABSTRACT FROM AUTHOR]

The paper describes the numerical calculations of a conceptual air brake valve of a trailer equipped with a differential section, which is intended to shorten response time and braking distance. The static flow characteristics have been determined using computational fluid dynamics (CFD). Mixed (global and local) computational meshes were used in the paper to determine the static flow characteristics of the valve sections. The use of the local mesh was relevant for valve openings smaller than 0.5mm. Using CFD, it was possible to determine the static flow characteristics of the main, auxiliary feed and the differential sections, which were linear, degressive and progressive depending on the section. The analyzes, which have not yet been described in the literature, showed a significant difference in the MFR of the additional and main feed tracts, which reached 52.29%.The results are applicable to the configuration of the braking system. Further research will include performing dynamic simulations using dedicated software and building a test rig to validate the CFD calculation results. [ABSTRACT FROM AUTHOR]

The integration of phase change materials (PCMs) into building structures has become a focal point for researchers aiming to enhance thermal comfort and energy efficiency in buildings. This comprehensive article delves into the analysis of PCMs embedded in room walls, emphasizing their role in thermal regulation and the innovative application of computational fluid dynamics (CFD) in evaluating their performance. [ABSTRACT FROM AUTHOR]

One of the most popular solar thermal applications, particularly in the field of water heating systems, is the solar water heater. The simple solar water heater has a low efficiency when compared to other types of solar water heaters, but it is inexpensive and durable. The optimization of water flow rate is another important parameter to improve the performance of a simple solar water heater. This paper explores the development, testing, and evaluation of a basic solar water heater in both natural-convection and forced-convection conditions. Experiments and analyses are conducted with two different systems: a basic solar water heater in a naturally convective environment (SSWH) and a more complex system in a forced convective environment (MSWH). Natural convection was used in the SSWH setup, while forced convection was used in the MSWH setup. A new design of MSWH setup is proposed for enhancement in conventional SSWH. The mass flow rates of 150LPH (liters per hour), 200LPH, and 250LPH are maintained via an attached pump in the MSWH setup. The two configurations' efficacy is also contrasted. The CFD simulation is also carried out for Natural and forced convective situations. When evaluating the performance of water heating systems, experimental and numerical simulations show good agreement. Average instantaneous collector efficiency of MSWH is 12.31%, 23.54%, and 9.0% higher than SSWH (when MSWH operated at 150LPH, 200LPH, and 250LPH flow rates, respectively). When operating at 150 LPH and 200 LPH flow rates, the average MSWH outlet temperature is 5.07% and 6.29% higher than the SSWH, respectively. When operating at 250 LPH flow rate, the average outlet temperature of MSWH is reduced by 25.49% compared to the SSWH. The obtained results demonstrate that the input radiation and flow intensity play a significant role in determining the collector's thermal performance, while other parameters are held constant. Lastly, some inferences and suggestions are drawn from the aforementioned experiments. [ABSTRACT FROM AUTHOR]

In the field of design and optimization of sophisticated geometries such as film-cooled turbine blades of modern jet engines, Computational Fluid Dynamics (CFD) simulation is commonly employed. As the pursuit for higher turbine entry temperatures intensifies, it becomes crucial for computational analyses to offer accurate predictions of metal temperatures and heat transfer coefficients on these critical components. This study investigates the impact of key physical factors that characterize the operation of these components on the accuracy of the computational model. In particular, the effects of including the exchange of thermal energy between the fluid and solid domains, as well as modelling the unsteady interaction between the rotor and stator are studied. The research focuses on a fully featured one-and-a-half stage high-pressure turbine of a commercial jet engine, utilizing proprietary software for conducting 3D Reynolds-Averaged Navier-Stokes flow simulations. To model the fluid-solid thermal interaction, steady-state Conjugate Heat Transfer (CHT) simulations are performed. The CHT results are then compared with experimental data obtained from a thermal paint test, achieving good levels of agreement. Additionally, phase-lag simulations are executed under adiabatic-wall conditions to evaluate the influence of stator-rotor interaction on near-wall gas temperatures. This work shows that, by modelling the periodic unsteadiness at the stator-rotor interface with a phase-lag technique, the maximum near-wall gas temperature prediction is significantly increased, sometimes more than 100K, with respect to the steady-state model one. Findings from this work also suggest that simplified "strip" source terms used to model the presence of film cooling hole rows on the surface of a blade can be used with satisfactory accuracy only for nominal conditions. The mass flows delivered by each source strip should not be linearly scaled based on mainstream quantities for use in different conditions, but they should be recalculated from scratch for the new conditions. [ABSTRACT FROM AUTHOR]

To investigate the influence of a moonpool on the nominal wake field of a ship during calm water navigation, computational fluid dynamics calculations are performed using the STAR-CCM + software. The analysis found that the influence of boundary layer separation in the moonpool causes the hull boundary layer thicker, which reduces the average axial velocity of the propeller behind the moonpool and enhances the wake. The uniformity of the axial velocity distribution at the propeller disc is also reduced, worsening the uniformity of the wake field. In addition, the wake field characteristics of rear propellers change periodically with the fluctuation of moonpool. As a result the propeller bearing force and vibration characteristics change periodically with not only blade frequency and multiple blade frequency, but also the fluctuation of moonpool. These phenomena make the performance of propellers on ships with moonpool different from that of normal ships. [ABSTRACT FROM AUTHOR]

If a layer of low-density water settles on top of higher density water, such as fresh water melting from a glacier and settling on top of colder seawater, a body of water can stratify into stable, distinct layers. A vessel advancing in such a stratified fluid can generate internal waves between these layers. The generation of internal waves requires energy and thus increases the resistance experienced by the vessel, a phenomenon known as the dead water effect which can result in a severe reduction in speed and loss of steering power. This study uses Computational Fluid Dynamics (CFD) to investigate the increase in ship resistance caused by the dead water effect. The results show that the presence of a stratified flow can increase total resistance approximately sixfold in extreme conditions. At standard operating conditions, total resistance may increase by approximately 6% as a result of flow stratification. [ABSTRACT FROM AUTHOR]

Propeller-hull vortex (PHV) cavitation is a special cavitating flow problem, which may cause severe negative effects on marine propeller performances. The present study shows a successful case of PHV cavitation elimination for a 900TEU container vessel. Numerical simulations and experiments are carried out to analyse and validate the PHV cavitation performance of different designs. Results show that the CFD simulation can capture the PHV for severe PHV cavitation cases but failed to directly capture PHV cavitation. The flow pattern obtained by CFD shows a rank on the likelihood of PHV cavitation for different designs, which is in agreement with model test results. The improved design with a small propeller and a wake equalising duct (WED) successfully eliminated the PHV cavitation. [ABSTRACT FROM AUTHOR]

The transport processes of saturated KCl solution and KCl solution–ethanol mixed improved tracer in a bare single-strand tundish were studied using water model experiments. The saturated KCl solution tracer exhibits severe short-circuiting flow and backflow, while the improved tracer exhibits plug flow behavior in the tundish, which is similar to ideal flow in computational fluid dynamics results. The volume effect of improved tracers on the flow field in the tundish is relatively weak and can be neglected. [ABSTRACT FROM AUTHOR]

The melting and motion of ferroalloys play a crucial role in the mass transfer and homogenization of molten steel in ladles. Heat transfer, melting, and solidification behavior of an alloy affect its size, thereby altering its motion within the gas-stirring ladle. This study established a heat transfer and solidification-melting model for alloy particles in high-temperature metal liquids. The computational fluid dynamics (CFD) method was used to simulate the fluid within the ladle, and the discrete element method (DEM) was employed for the alloy particles. This coupling approach elucidates the motion trajectories of different types of alloys in molten steel under flow and heat exchange, particle heating, melting, and shrinkage conditions. Furthermore, the effects of alloy size, initial alloy temperature, molten steel flow rate, and molten steel temperature on the melting behavior of different types of alloys were investigated. The results showed that the melting time exponentially increased with increasing alloy size or decreasing molten steel flow rate. Moreover, the alloy melting time decreased with increasing initial alloy temperature or molten steel temperature. The impact of these factors on the melting of FeCr, FeMn, FeSi, and Al alloys was also evaluated. Furthermore, FeSi and Al alloys added at different positions in the ladle with symmetric dual gas bottom blowing had a residence time of only 1 second in the molten steel and did not completely melt. These findings indicate that FeSi, Al, and FeCr alloys should be added at the 0.4R position in the symmetrical plane. Furthermore, the − 0.4R or − 0.2R positions are more favorable for the melting of FeMn. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive numerical analysis of a full‐scale horizontal‐axis floating offshore wind turbine (FOWT) rotor subjected to harmonic surging motions under both laminar and turbulent inflow conditions. Utilizing high‐fidelity computational fluid dynamics (CFD) simulations, namely, large eddy simulation (LES) with actuator line model (ALM), this research investigates the rotor performance, wake characteristics, and wake structures of a surging FOWT in detail. The study delves into the influence of varying inflow turbulence intensities, surging settings, and their interplay on the aerodynamic performance and the wake aerodynamics of a FOWT rotor. The results show that, through employing the phase‐averaging technique, surge‐induced periodic coherent structures (SIPeCS) can be identified in the wake of all the surging cases studied, irrespective of the inflow conditions and the surging settings. Additionally, the findings show that the faster wake recovery observed in the surging cases is not caused by enhancing the instability‐induced turbulence level, a previously accepted hypothesis. Instead, the results indicate that it is due to the enhanced advection process resulting from the induction fields of SIPeCS that causes the wake to recover faster. The analysis of rotor performance shows that the time‐averaged rotor performances are affected by the intricate aerodynamics arising from the surging motions. With certain surging settings, the time‐averaged thrust and the time‐averaged power of a surging rotor are found to be simultaneously lower and higher compared with those of a fixed rotor. Furthermore, the study underscores the importance of considering both the magnitude of surging and the rate of surging simultaneously to fully characterize the hysteresis load on a surging rotor. [ABSTRACT FROM AUTHOR]

This paper represents a detailed and systematic review of one of the most ongoing applications of computational fluid dynamics (CFD) in biomedical applications. Beyond its various engineering applications, CFD has started to establish a presence in the biomedical field. Cardiac abnormality, a familiar health issue, is an essential point of investigation by research analysts. Diagnostic modalities provide cardiovascular structural information but give insufficient information about the hemodynamics of blood. The study of hemodynamic parameters can be a potential measure for determining cardiovascular abnormalities. Numerous studies have explored the rheological behavior of blood experimentally and numerically. This paper provides insight into how researchers have incorporated the pulsatile nature of the blood experimentally, numerically, or through various simulations over the years. It focuses on how machine learning platforms derive outputs based on mass and momentum conservation to predict the velocity and pressure profile, analyzing various cardiac diseases for clinical applications. This will pave the way toward responsive AI in cardiac healthcare, improving productivity and quality in the healthcare industry. The paper shows how CFD is a vital tool for efficiently studying the flow in arteries. The review indicates this biomedical simulation and its applications in healthcare using machine learning and AI. Developing AI-based CFD models can impact society and foster the advancement towards responsive AI. [ABSTRACT FROM AUTHOR]

The impact of an innovative trailing-edge flap (blended TEF) on the aerodynamic performance of small-scale horizontal-axis wind turbines is numerically and experimentally studied. The blended TEF is characterized by both the pressure surface of the hinged TEF and the suction surface of the morphed TEF. The wind speed, rotational speed, and power coefficient of four wind turbines were measured in a wind tunnel. The results show that the wind turbines with the morphed and hinged blades were respectively the easiest and hardest to start, and respectively had the lowest and highest output axial thrust. Moreover, the wind turbines with the hinged and blended blades were found to have the lowest and highest output power, respectively. Compared with the original wind turbine, the wind turbine with the blended blade respectively resulted in additional power and thrust increases of 130.95% and 113.49% at the wind speed of 1.29 m/s. [ABSTRACT FROM AUTHOR]

Underwater data centers, with their low energy use, cost, and latency, are seen as the future of data centers. This paper designs a Total Auxiliary System (TAS) for underwater data centers, including temperature and humidity control unit, biofouling prevention, and seawater corrosion prevention. In this paper, a model for the temperature and humidity control unit was developed, and key parameters such as heat load, specific moisture extraction rate (SMER), coefficient of performance (COP), and dehumidification volume were simulated. The effectiveness of the cooling performance was verified using Computational Fluid Dynamics (CFD) simulations. The system design also includes biofouling prevention via electric pulse and seawater corrosion prevention using cathodic protection with plastic coating and applied current. Calculations and verifications show that this system reduces energy consumption and ensures the long-term stable operation of underwater data centers. [ABSTRACT FROM AUTHOR]

In the framework of process safety studies, consequence assessment of accidental scenarios is a crucial step affecting the eventual risk profile associated with the facilities under analysis. Conventional models used for consequence assessment are based on integral models, and may not be adequate to cope with the dynamic evolution of accidental scenarios and their three‐dimensional features. On the other hand, consequence assessment models based on computational fluid dynamics (CFD) approaches are promising to cope with complex scenarios and environments, but setting the simulation introduces relevant uncertainties associated with both the input data, assumptions, and with the modelling of physical effects involved. In the present study, uncertainty quantification (UQ) techniques are applied to support advanced safety studies based on CFD simulations of hazardous gas dispersion. Firstly, the accidental scenarios are characterized by defining release scenarios and conditions and quantifying source terms using integral models. At the same time, input meteorological data are gathered. This enables the development of high‐fidelity CFD simulations of gas dispersion based on different input sets and eventually the implementation of UQ techniques. The generalized polynomial chaos (gPC) expansion is employed to obtain hazardous gas concentration based on the variation of wind direction and speed. The present method is applied for the analysis of a real plant featuring a complex layout. The results show the advantages of the present approach by quantifying the influence of meteorological conditions and providing indications for supporting the development of protection systems and emergency measures. [ABSTRACT FROM AUTHOR]

Shale reservoirs are highly complex and are difficult to study using conventional reservoir simulation tools. This study introduces a novel methodology for estimating production from complex shale gas reservoirs by coupling decline curve analysis (DCA) with computational fluid dynamics (CFD) simulations. The proposed method uses exponential DCA to analyze production data from a dual porosity–permeability shale gas transport model. These complexities include fracture characteristics, geomechanical properties, nanopore confinement effects, and multiple flow mechanisms contributing to the total production performance. The shale gas transport model is validated through historical production data from Marcellus shale. The new methodology also tests fracture characteristics. It shows that increased porosity and permeability will increase the recoverable reserves but will have varying effects on the decline rate. The paper demonstrates the advantages of the proposed methodology over conventional reservoir simulation tools. It provides insights into the factors affecting shale gas production performance through the inclusion of the complexities of an unconventional shale gas reservoir. The paper provides a proof of concept on the particular reservoir of which the field data is provided—Barnett and Marcellus Shale. [ABSTRACT FROM AUTHOR]