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Copyright of Light Industry Machinery is the property of Light Industry Machinery Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Light Industry Machinery is the property of Light Industry Machinery Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article explores into the relationship between urban morphology and renewable energy, specifically focusing on the potential for active solar and wind energy in building facades and non-built-up spaces within blocks in Addis Ababa, a typical Sub-Saharan Africa city. The study involved the analysis of eleven urban blocks representing four different urban morphology typologies selected with geospatial clustering. Solar and wind data are obtained from satellite-based and meteorological sources. Wind and solar analyses are conducted using computational fluid dynamics through Ansys Fluent and Rhino Grasshopper in Ladybug, respectively, with the support of ArcGIS. The findings reveal that the changes in the values of some morphological descriptors have inverse relationship when comparing solar and wind potential on building facades. Conversely, changes in the values of other morphological descriptors generally show a direct relationship independently on solar and wind potential on the non-built up space. It is recommended that the combined effects of solar and wind potential on urban facades be considered based on morphological descriptors. Similarly, the independent effects of solar and wind potential on non-built-up spaces should also be recommended according to these descriptors. [ABSTRACT FROM AUTHOR]

In addition to convective heat transfer, radiation heat transfer constitutes a significant component of the thermal performance of Passive Containment Air-Cooling System (PAS). The installation of radiation plates within the PAS flow channel enhances the convective heat transfer area between the wall and the air, an effect that should not be overlooked. ANSYS Fluent was employed to investigate how the placement and quantity of radiation plates influence the heat transfer efficiency of PAS. The computational results indicate that radiation plates can substantially enhance the thermal performance of PAS. Specifically, when a radiation plate is positioned 0.9 m from the inner wall of the concrete shell, an improvement in PAS heat transfer power by as much as 34.4% can be achieved. However, it was observed that increasing the number of radiation plates has a minimal impact on overall performance; thus, utilizing multiple plates does not further augment the PAS heat transfer capability. Nonetheless, incorporating several radiation plates may contribute to lowering the temperature of the concrete shell. Based on this research, it can be concluded that strategically arranging radiation plates significantly improves the PAS heat transfer capacity. While multiple radiation plates do not provide additional enhancements to heat transfer efficiency under normal conditions, they remain a viable option for mitigating concrete shell temperatures during accident scenarios. [ABSTRACT FROM AUTHOR]

Refrigerants are one of the major contributors for earths Global Warming Potential which is resulting in extreme weather conditions. In the present study, Finite Volume-based VOF (volume of fluid) model is used to investigate the flow behavior of ecofriendly friendly refrigerants (R161, R1123 and R454b) flowing inside the capillary tube. To estimate mass transfer during flashing, Lee model is used. The present study considers different lengths and diameters of straight capillary tube to analyze their effects on flow characteristics of refrigerant such as pressure, temperature, volume fraction and velocity. It is understood that larger diameter expansion capillary results in high capillary exit pressures for the same operating conditions. It was found that the order of velocities are almost 1.2 times higher for R161 when compared to R1123. It is also calculated that mass flow rate of R454B is 25% less and 50% high when compared with refrigerant R1123 and R161.The numerical investigation also showed that under the same operating conditions, R161 has higher COP as compared to other refrigerants whereas in terms of refrigeration effect R454B is better than other refrigerants. [ABSTRACT FROM AUTHOR]

Sandstorms have destructive effects on railway infrastructures due to the movement and erosion of sand. One of the proposed solutions to reduce the impact of windblown sand on desert railways is the hump slab track superstructure. This system entails removing the ballast layer and elevating the rails using concrete foundations called humps, which create sand movement channels beneath the rails. The hump's geometry must not only meet optimal aerodynamic conditions but also ensure ample clearance for sand passage, maintaining structural stability and efficient railway performance. In this study, the aerodynamic evaluation of various hump geometry is examined considering the elliptical (EL) and semicircular-rectangular (CR) shapes. Simulations are carried out using 3D computational fluid dynamics in ANSYS Fluent software. A gas–solid two-phase model, comprising a distinct phase for sand particles and another for air, is developed to assess the sand movement capacity through the selected hump geometries. A wind tunnel experiment is then performed on a prototype of a hump slab track to validate the software model. The findings highlighted that the CR shape, with a height of 25 cm, resulted in the most favorable outputs. [ABSTRACT FROM AUTHOR]

As there is a risk of CO contamination by vehicles running inside the car park. This research was initiated with the objective of assessing jet fans' impulsive ventilation "IV" performance and studying its effect on CO contamination in such garages, where a 1350 m2 UG (2.65 m high) was considered as a case study. 39 scenarios were proposed; visualized in a matrix, and simulated by a Computational Fluid Dynamics "CFD" model (ANSYS FLUENT 2019 R3), natural ventilation, and impulsive ventilation were studied. The proposed scenarios considered the jet fans "JFs" arrangement, in terms of number and interspacing and location within the garage, flow of JFs, and load capacity, in terms of the number of cars in operation. A code notation was made to describe each case's properties. The results highlighted valuable insights into the optimal arrangement of jet fans in UG. It flagged the importance of adjusting the number of fans, spacing, and location to attain reasonable ventilation performance. The research suggested implementing an inverter variable speed drive in the ventilation system to provide 6 or 10 ACH and adjusting them based on UG occupancy whether at normal load or peak load, Additionally, the On-Off system allows for the utilization of different arrangements according to the load requirements. A collective correlation was attempted to identify the values of CO in PPM according to load percentage and ACH. [ABSTRACT FROM AUTHOR]

This study compares the performance of serpentine and spiral Earth-Air Heat Exchanger (EAHE) designs using ANSYS Fluent for numerical simulations, under varying inlet temperatures, flow rates, and lengths. The models were validated against experimental data for the serpentine design and numerical results for the spiral design, confirming their accuracy. The simulations focused on outlet temperatures and pressure losses at depths of 2 and 3 meters. Results show that both designs achieve similar thermal performance, with minor differences in outlet temperatures and pressure losses. At a depth of 3 meters, both designs reach outlet temperatures within the comfort range, with the spiral design exhibiting lower pressure losses. For example, at an inlet temperature of 46.1℃ and a flow rate of 130 m3 /h, the serpentine EAHE achieves an outlet temperature of 30.21℃ with a pressure loss of 77 Pa, while the spiral EAHE achieves 30.02℃ with 61 Pa. While the serpentine design offers slightly better temperature reduction, it incurs higher pressure losses due to turbulence at 90° bends. These findings underscore the need to consider both thermal performance and pressure losses when selecting the optimal EAHE design, as both configurations demonstrate effectiveness in cooling under the studied conditions. [ABSTRACT FROM AUTHOR]

The purpose of this study is to analyze the hydrodynamic performance and efficiency of a dual‐chamber oscillating water column (OWC) device. For the Joint North Sea Wave Project (JONSWAP) incident waves spectrum, a two dimensional numerical wave tank is employed with nonlinear Reynolds averaged Navier–Stokes equations model along with the standard k−ϵ$$ k-\epsilon $$ turbulence model. The free surface elevation is measured using the volume of fluid method. The numerical simulation demonstrates the streamline and velocity vector profiles throughout an entire pressure fluctuation cycle inside the chambers of the given OWC device. Further, investigation is carried out to analyze the impact of pressure drop and air flow rate through the orifice of the dual‐chamber OWC device on the power generation. Moreover, the power spectral density analysis of the free surface elevation is provided to know the variation of the parameters in the frequency domain. These results demonstrate that the effectiveness of the dual‐chamber OWC device is more near the significant wave height Hs=1.50$$ {H}_s=1.50 $$ m. [ABSTRACT FROM AUTHOR]

Poor wellbore cleaning is a significant challenge in oil drilling, primarily due to the accumulation of cuttings at the bottom of the well, particularly in deviated and horizontal wells. This study addresses this issue by employing Computational Fluid Dynamics (CFD) with the commercial software ANSYS FLUENT (2023-R1) to simulate a solid–liquid multiphase flow in an annulus. The primary objective is to analyze the cuttings concentration, pressure loss, and solid velocity profiles across various drilling parameters, including drill pipe rotation, the flow rate, rate of penetration, inclination angle, and fluid rheology. Our results underscore the critical role of these parameters in enhancing cuttings transport efficiency. Specifically, the drill pipe rotation, flow rate, and rate of penetration emerge as the most influential factors affecting the wellbore cleaning performance. With a validated model exhibiting an average error of 4.24%, this study provides insights into optimizing drilling operations to improve wellbore cleaning and increase hydrocarbon recovery. [ABSTRACT FROM AUTHOR]

For the time being, there is a growing endeavor towards supporting energy-saving technologies, most significantly heat exchanger systems, by improving the performance of the heat transfer process. The study model employed is a double-pipe heat exchanger (DPHEX), which is served in an actual project at the Low-Density Polyethylene (LDPE) unit of the State Company for Petrochemical Industries in Basra, Iraq. The prominent goals of this study are to gain a deeper comprehension of the exchanger's performance under advanced operating conditions and to maximize the efficiency of heat transfer between the two fluids in the DPHEX system. The current work applies a distinctive connection of SOLIDWORKS with ANSYS FLUENT software to conduct a simulation design and computational fluid dynamics (CFD) analysis of a heat transfer system in DPHEX. Thermal analysis of exchangers is challenging since many parameters, such as the geometry of the heat exchangers and the varying flow regimes influence the overall heat transfer coefficient. As a result, a Genetic Algorithm (GA) was employed to investigate the optimal design and operating conditions of DPHEX, using a COM server to provide flexible communication between the MATLAB GA toolbox and Aspen HYSYS® software. The preliminary findings from ANSYS FLUENT simulations and GA optimizations demonstrated significant improvements. Specifically, the heat transfer rate rose by 24% and 28%, respectively, also there made up an elevate in the overall heat transfer coefficient to 675 W/m²·K and 751 W/m²·K, correspondingly, from 440 W/m²·K in the as-built heat exchanger. Notably, these results were observed while the outgoing temperature of the chilled ethylene gas was at 49, and the efficiency accounted for 87.7%. The study exhibited the feasibility of reducing the cooling water quantity from the traditional mass flow rate of 73.860 kg/hr to 50.400 kg/hr while maintaining a reasonable efficiency of 83% at the LDPE unit. These results were achieved with the leaving temperature of ethylene gas and cooling water set at 50 and 34, respectively. Hence, minimizing water consumption in heat exchangers brings about environmental, economic, and operational advantages. Generally, the study results have reinforced the importance of simulation tools and their direct contribution to achieving efficient and eco-friendly energy systems. [ABSTRACT FROM AUTHOR]

This article addresses the study of internal flow dynamics within a cryogenic chamber designed for freezing food using liquid nitrogen injection. The chamber features a circular section with strategically placed jet-type atomizers for this purpose. The primary objective is to extend the residence time of the cryogenic fluid within the chamber to ensure uniform and effective freezing of the passing food items. This is achieved by inducing a swirl effect through strategic deceleration of the flow using the atomizers. The meticulous placement of these atomizers at periodic intervals along the internal walls of the cylindrical chamber ensures prolonged recirculation of the internal flow. Internal temperature analysis is crucial to ensure the freezing process. The study is supported by numerical analysis in CFD ANSYS to assess the dynamics of the swirl effect and parameters associated with the nitrogen–air interface, from which we obtain a sophisticated analysis thanks to the design of a hexahedral mesh made in greater detail in ICEM CFD. This approach aims to understand internal flow behavior and its correlation with the complexity of cryogenic system design, utilizing variable nitrogen-injection pressures and strategic atomizer placement as fundamental parameters to optimize system design. [ABSTRACT FROM AUTHOR]

Introduction/purpose: In this research, the influence of different turbulence models on the aerodynamic drag prediction of a generic spin-stabilized projectile was analyzed. The turbulence models chosen for investigation were one-equation Spalart-Allmaras, two-equation models Standard k-e, Realizable k-e, Standard k-o and SST k-o. The special sniper projectile M118 was selected for the study. Methods: The flows around the projectile were numerically simulated using RANS equations intergrated into ANSYS Fluent software with different turbulence models. The numerical simulation was carried out at various Mach numbers to study the effect of turbulence models on the projectile aerodynamic drag prediction. The computational results were compared to the available experimental data to evaluate the ability of the turbulence models. Results: The research results have shown that the turbulence models significantly affect the numerical simulation results. The Spalart-Allmaras turbulence model performs better than other models in the subsonic flow regime. The Standard k-e, Realizable k-e and SST k-o models perform better than other models in the supersonic flow regime. Conclusion: Computational Fluid Dynamics is a powerful tool to analyze the aerodynamics of flying bodies. By appropriately selecting turbulence models, the flow around flying bodies can be accurately investigated. In the case of generic ogive-cylinder-boattail projectiles, on the one hand, the Spalart-Allmaras model is suitable for subsonic flow, and the Standard k-e, Realizable k-e and SST k-o models are recommended for the supersonic flight regime, on the other hand.

Abstract Sandstorms have destructive effects on railway infrastructures due to the movement and erosion of sand. One of the proposed solutions to reduce the impact of windblown sand on desert railways is the hump slab track superstructure. This system entails removing the ballast layer and elevating the rails using concrete foundations called humps, which create sand movement channels beneath the rails. The hump’s geometry must not only meet optimal aerodynamic conditions but also ensure ample clearance for sand passage, maintaining structural stability and efficient railway performance. In this study, the aerodynamic evaluation of various hump geometry is examined considering the elliptical (EL) and semicircular-rectangular (CR) shapes. Simulations are carried out using 3D computational fluid dynamics in ANSYS Fluent software. A gas–solid two-phase model, comprising a distinct phase for sand particles and another for air, is developed to assess the sand movement capacity through the selected hump geometries. A wind tunnel experiment is then performed on a prototype of a hump slab track to validate the software model. The findings highlighted that the CR shape, with a height of 25 cm, resulted in the most favorable outputs.

Poor wellbore cleaning is a significant challenge in oil drilling, primarily due to the accumulation of cuttings at the bottom of the well, particularly in deviated and horizontal wells. This study addresses this issue by employing Computational Fluid Dynamics (CFD) with the commercial software ANSYS FLUENT (2023-R1) to simulate a solid–liquid multiphase flow in an annulus. The primary objective is to analyze the cuttings concentration, pressure loss, and solid velocity profiles across various drilling parameters, including drill pipe rotation, the flow rate, rate of penetration, inclination angle, and fluid rheology. Our results underscore the critical role of these parameters in enhancing cuttings transport efficiency. Specifically, the drill pipe rotation, flow rate, and rate of penetration emerge as the most influential factors affecting the wellbore cleaning performance. With a validated model exhibiting an average error of 4.24%, this study provides insights into optimizing drilling operations to improve wellbore cleaning and increase hydrocarbon recovery.

Introduction/purpose: In this paper, the influence of muzzle velocity and the initial friction between the sabot and the penetrator of a sub-caliber bullet on the separation process was investigated. A special armor-piercing bullet was chosen as a research object. Methods: A hybrid approach was applied in the study to solve the set tasks. In the first place, the equation system describing the motion of the sabot and the penetrator was established analytically. The aerodynamic drags acting on the sabot and the penetrator were then obtained numerically using CFD methods. Eventually, the equations of motion of the sabot and the penetrator were solved using the Runge-Kutta method to analyze the effect of the bullet muzzle velocity and the initial friction of the sabot and the penetrator on the separation process. Results: The research results have shown the significant influence of the bullet muzzle velocity and the initial friction on the parameters of the sabot and the penetrator at the very moment they completely separate from each other. Based on the obtained data, weapon designers can appropriately select the ballistic and structural parameters for the bullet. Conclusion: The hybrid approach presented in this paper is effective in studying the separation process of armor-piercing saboted bullets. The research results are useful contributions to the field of sub-caliber ammunition. The presented method can be applied in the design process of armor-piercing saboted projectiles of different calibers.

Due to the intense loading of the elements of launch structures when exposed to rocket engine jets, it is obvious that it is necessary to determine the gas-dynamic, thermal and other loads that occur during the launch of the launch vehicle. Numerical modeling using application programs is one of the widely used methods of their calculation, since physical modeling requires significant resources. The study analyzes the case of interaction of a single supersonic gas jet with a flat barrier oriented perpendicular to the direction of the jet. Differential equations describing the motion of a compressible viscous heatconducting gas (Navier-Stokes equations) are presented, and a method for averaging them by Reynolds is described. Some one- and two-parameter turbulence models based on Reynolds equations are considered. A numerical simulation of the flow of a supersonic jet of air from a Laval nozzle onto a flat aluminum barrier located perpendicular to the axis of the jet is carried out. The ANSYS Fluent software package is used to analyze the effect of choosing a turbulence model on the distribution of the Mach number and pressure on the barrier. A comparison of the results of the study with experimental data showed that the most accurate results are obtained using the k-ω SST turbulence model.

Ansys Fluent can be used in chemical engineering to draw velocity profiles, temperature profiles inside pipes and columns and determine pressure losses, making 2D and 3D simulations of mass separation processes using user defined functions. Computational fluid dynamics (CFD) software can be applied for the analysis of photoreactors, which initiate and sustain chemical reactions through the application of light energy. Photoreactors can be used in a variety of industries and their performance can significantly impact the efficiency of the chemical processes they support. In this study, Ansys Fluent flow simulation was applied in order to improve the design of proposed photoreactor. Firstly, base photoreactor models were simulated via Ansys Fluent CFD software. Accordingly, these base models were further developed in order to obtain high fluid velocity and homogenous flow by adding baffles and nozzles. The effects of baffle height and spacing on the total velocity and flow homogeneity were also investigated. All models were analysed with the total fluid velocity on selected points and standard deviation between the velocity data. Optimal photoreactor design with the highest fluid velocity and homogenous flow distribution was developed. [ABSTRACT FROM AUTHOR]

This paper aims at the PCM-based heat sink for electronic cooling. In the present analysis, paraffin wax-based phase change material (PCM), in 3-fin and 4-fin hollow heat sinks with the proper volume of PCM in the temperature of the electronic components can be controlled. The PCM-filled heat sinks are placed on top of the high heat-generating integrated circuit (IC) components. The aim is to reduce the maximum temperature of the electronic components and keep them below their critical temperature, hence increasing the life of the IC chips. A correlation is put forward for dimensionless temperature (θ) in terms of heat flux ( q ∗ ), volume content ( v ∗ ) and size of the IC chips (δ). It has been found that there will be a 4– 6 ∘ C drop in temperature when compared to solid fins heat sinks. It is confirmed that the temperature of the IC chip is a strong function of heat flux, size and volume content of PCM. [ABSTRACT FROM AUTHOR]

This paper analyzes the components of the aerodynamic drag of a small-caliber bullet using a numerical simulation method. The analyses are applied to the M855 bullet. The turbulence model k-ε is used. The mesh size of 2.16 million elements is applied. The simulation method has been verified by comparing the obtained results with experimental data. The wave drag accounts for the largest proportion (about 50%), the friction drag accounts for the smallest proportion (from 10% to 15%), the base drag accounts for a significant proportion (from 35% to 45%) of the total drag at Mach number from 1.47 to 2.62. Two modified M855 bullets have been studied. The obtained results showed that the variation of increasing the length of the bullet nose is the most reasonable to be adopted. The method presented in this paper can be used in the projectile design process to optimize its shape for reducing the aerodynamic drag. [ABSTRACT FROM AUTHOR]

This paper deals with CFD analyses of the difference in the nature of the shock waves in supersonic flow under atmospheric pressure and pressure conditions at the boundary of continuum mechanics for electron microscopy. The first part describes the verification of the CFD analyses in combination with the experimental chamber results and the initial analyses using optical methods at low pressures on the boundary of continuum mechanics that were performed. The second part describes the analyses on an underexpanded nozzle performed to analyze the characteristics of normal shock waves in a pressure range from atmospheric pressure to pressures at the boundary of continuum mechanics. The results obtained by CFD modeling are prepared as a basis for the design of the planned experimental sensing of density gradients using optical methods, and for validation, the expected pressure and temperature courses from selected locations suitable for the placement of temperature and pressure sensors are prepared from the CFD analyses. [ABSTRACT FROM AUTHOR]

The present study endeavours to substantially contribute towards alleviating the global water scarcity problem. The task entailed designing a computational model of a renewable energy-based evaporator. Using ANSYS Fluent, the CFD simulations of a three-dimensional conventional continuous single slope, single basin solar still were carried out in summer at 23.79°N, 86.43°E coordinates. With the optimized inclination condensation angle of 29° and water depth at 1 cm, the solar still recorded the highest hourly drinking water, about 1.5 kg m-2, at 11:00 h. The continuous production resulted in a water collection rate of 8.6 kg m-2 day-1, encompassing the production of all previous models. Additionally, compared with the literature correlation for solar still simulated mass, the Power model calculation was the closest, with a 12.4% variation. Furthermore, the study showcases that CFD is an economical, efficient, and easily diagnosable technique for designing solar stills. [ABSTRACT FROM AUTHOR]

Understanding the ecological conditions of vegetation growth in water sources is vital to appraise the influence of vegetation on river engineering. Based on the experimental information that is accessible, the consequences of vegetation on flow resistance is described as an alteration in the drag coefficient and the planned area. The current study analytically estimates the vertical distribution of stream-wise velocity in open-channel flow while considering rigid and flexible vegetation. The flow is vertically separated into top free water layer and bottom vegetation layer using the projected deflection height of both vegetation. Related momentum calculations for each layer are then derived. Based on the gathered experimental data, a 3D numerical model with various simulation situations is used to model, calibrate, and evaluate the artificial cylinders. A considerable deflection analysis is utilised to calculate the velocity-dependent stem height. This has proven to be more precise compared to formerly deflection investigation. The estimated outcomes show that precise predictions may be made for the vertical contours of vertical Reynolds shear stress based on mean horizontal velocity. The numerical simulations demonstrate that plant flexibility reduces the vertical Reynolds shear stress and prompted flow resistance force of the vegetation. [ABSTRACT FROM AUTHOR]

This article explores into the relationship between urban morphology and renewable energy, specifically focusing on the potential for active solar and wind energy in building facades and non-built-up spaces within blocks in Addis Ababa, a typical Sub-Saharan Africa city. The study involved the analysis of eleven urban blocks representing four different urban morphology typologies selected with geospatial clustering. Solar and wind data are obtained from satellite-based and meteorological sources. Wind and solar analyses are conducted using computational fluid dynamics through Ansys Fluent and Rhino Grasshopper in Ladybug, respectively, with the support of ArcGIS. The findings reveal that the changes in the values of some morphological descriptors have inverse relationship when comparing solar and wind potential on building facades. Conversely, changes in the values of other morphological descriptors generally show a direct relationship independently on solar and wind potential on the non-built up space. It is recommended that the combined effects of solar and wind potential on urban facades be considered based on morphological descriptors. Similarly, the independent effects of solar and wind potential on non-built-up spaces should also be recommended according to these descriptors.

Abstract The purpose of this study is to analyze the hydrodynamic performance and efficiency of a dual‐chamber oscillating water column (OWC) device. For the Joint North Sea Wave Project (JONSWAP) incident waves spectrum, a two dimensional numerical wave tank is employed with nonlinear Reynolds averaged Navier–Stokes equations model along with the standard k−ϵ turbulence model. The free surface elevation is measured using the volume of fluid method. The numerical simulation demonstrates the streamline and velocity vector profiles throughout an entire pressure fluctuation cycle inside the chambers of the given OWC device. Further, investigation is carried out to analyze the impact of pressure drop and air flow rate through the orifice of the dual‐chamber OWC device on the power generation. Moreover, the power spectral density analysis of the free surface elevation is provided to know the variation of the parameters in the frequency domain. These results demonstrate that the effectiveness of the dual‐chamber OWC device is more near the significant wave height Hs=1.50 m.

Annular flow refers to a special type of two-phase flow pattern in which liquid flows as a thin film at the periphery of a pipe, tube, or conduit, and gas with relatively high velocity flows at the center of the flow section. This gas also includes dispersed liquid droplets. The liquid film flow rate continuously changes inside the tube due to two processes-entrainment and deposition. To determine the liquid holdup, pressure drop, the onset of dryout, and heat transfer characteristics in annular flow, it is important to have proper knowledge of flow characteristics. Especially a better understanding of entrainment fraction is important for the heat transfer and safe operation of two-phase flow systems operating in an annular two-phase flow regime. Therefore, the objective of this work is to develop a computational model for the simulation of the annular two-phase flow regime and assess the various existing models for the entrainment rate. In this work, Computational Fluid Dynamics (CFD) in ANSYS FLUENT has been applied to determine annular flow characteristics such as liquid film thickness, film velocity, entrainment rate, deposition rate, and entrainment fraction for various gas-liquid flow conditions in a vertical upward tube. The gas core with droplets was simulated using the Discrete Phase Model (DPM) which is based on the Eulerian-Lagrangian approach. The Eulerian Wall Film (EWF) model was utilized to simulate liquid film on the tube wall. Three different models of Entrainment rate were implemented and assessed through user-defined functions (UDF) in ANSYS. Finally, entrainment for fully developed flow was determined and compared with the experimental data available in the literature. From the simulations, it was obtained that the Bertodano correlation performed best in predicting entrainment fraction and the results were within the ±30 % limit when compared to experimental data.

Drag and lift are two important parameters to evaluate a vehicle's aerodynamic performance. Aerodynamic resistance (drag force Fd) prevents the movement of the vehicle and has a value proportional to the square of the velocity. That is, when the speed increases twice, the aerodynamic drag will increase fourfold. This article presents a plan to design a sport utility vehicle model with improved aerodynamics by using Ansys Fluent software to analyze pressure distribution areas that affect aerodynamics and the body. Based on the results obtained, the areas of stress and maximum pressure concentration have been identified. From this, a plan to improve the vehicle’s exterior design has been proposed. After many iterations of the design and model optimization process, the aerodynamic drag coefficient CD was reduced by 3.06% compared to the original model. The revised design option is equipped with an airflow diffuser under the vehicle; the lifting resistance coefficient has been reduced from 0.0902 to 0.038, equivalent to 58.2%. The new proposed design of the model has reduced the vehicle's frontal drag by 2.04%. The research results have determined the aerodynamic coefficients CD and CL of the model car. Based on the results received, it is possible to compare them with the manufacturer's announced parameters and propose new design options that still ensure aesthetics.

Understanding the ecological conditions of vegetation growth in water sources is vital to appraise the influence of vegetation on river engineering. Based on the experimental information that is accessible, the consequences of vegetation on flow resistance is described as an alteration in the drag coefficient and the planned area. The current study analytically estimates the vertical distribution of stream-wise velocity in open-channel flow while considering rigid and flexible vegetation. The flow is vertically separated into top free water layer and bottom vegetation layer using the projected deflection height of both vegetation. Related momentum calculations for each layer are then derived. Based on the gathered experimental data, a 3D numerical model with various simulation situations is used to model, calibrate, and evaluate the artificial cylinders. A considerable deflection analysis is utilised to calculate the velocity-dependent stem height. This has proven to be more precise compared to formerly deflection investigation. The estimated outcomes show that precise predictions may be made for the vertical contours of vertical Reynolds shear stress based on mean horizontal velocity. The numerical simulations demonstrate that plant flexibility reduces the vertical Reynolds shear stress and prompted flow resistance force of the vegetation.

The utilization of unmanned sailboats as a burgeoning instrument for ocean exploration and monitoring is steadily rising. In this study, a dual sail configuration is put forth to augment the sailboats' proficiency in its wind-catching ability and adapt to the harsh environment of the sea. This proposition is based on a thorough investigation of sail aerodynamics. The symmetric rigid wing sails NACA 0020 and NACA 0016 are selected for use as the mainsail and trailing wing sail, respectively, after considering the operational environment of unmanned sailboats. The wing sail structure is modeled using SolidWorks, and computational fluid dynamics (CFD) simulations are conducted using ANSYS Fluent 2022R1 software to evaluate the aerodynamic performance of the sails. Key aerodynamic parameters, including lift, drag, lift coefficient, drag coefficient, and thrust coefficient, are obtained under different angles of attack. Furthermore, the effects of mainsail aspect ratios, mainsail taper ratios, and the positional relationship between the mainsail and trailing sail on performance are analyzed to determine the optimal structure. The thrust provided by the sail to the boat is mainly generated by the decomposition of lift, and the lift coefficient is used to measure the efficiency of an object in generating lift in the air. The proposed sail structure demonstrates a 37.1% improvement in the peak lift coefficient compared to traditional flexible sails and exhibits strong propulsion capability, indicating its potential for widespread application in the marine field. [ABSTRACT FROM AUTHOR]

This study employed numerical analysis to evaluate the sustainability of Serpentine Flow-Field and Straight channel PEM fuel cells, focusing on critical parameters such as reactant velocity, temperature, current density, water content, membrane hydration, and polarization behavior curve. The model incorporated the transportation of gases, water, and electrical current within the fuel cell's layers, emphasizing the importance of optimizing performance and reducing costs through the design of the membrane electrode assembly (MEA). Utilizing the finite element method and ANSYS Fluent, the model allowed for adjustments in parameters such as membrane thickness and protonic conductivity coefficient, both of which significantly impact cell performance. The findings indicated that both fuel cell designs performed well, with a slight advantage observed for the Straight channel configuration in terms of production. However, the performance difference was relatively small, with the Straight channel design outperforming the Serpentine Flow-Field configuration by approximately 5% in terms of production. Despite this slight discrepancy, both designs demonstrated good performance overall. Moreover, the study underscored the critical role of MEA design optimization in achieving maximum performance and cost-effectiveness. While Straight channel PEM fuel cells may be slightly more cost-effective for certain applications, Serpentine Flow-Field PEM fuel cells offer enhanced efficiency and durability, making them preferable in many scenarios. In conclusion, this research provides valuable insights into the sustainability of these two fuel cell designs, indicating that while both are viable options, Serpentine Flow-Field PEM fuel cells offer slightly better performance and durability, thus warranting consideration for future applications. [ABSTRACT FROM AUTHOR]

In this paper, the landscape of typical roadway trees and their planting parameters on Pingtan Island are investigated and analyzed in the field. A three-dimensional model of street trees was created using AutoCAD 2020, and Ansys Fluent 2022 was used to simulate the wind condition of trees with various planting parameters under high wind circumstances. The study explores the stress and adaptability of roadway trees in the wind environment under different planting parameters, such as different heights, plant spacing, lower shrub heights, and two-row and three-row planting with different row spacings. The results show that the wind resistance of street trees is connected to the planting parameters and that modifying the appropriate planting parameters can improve the wind stability of road green space. The height of street trees is more suitable between 6.0~9.0 m. The planting spacing should be not less than 1.0 times the crown and not more than 1.75 times the crown. The form of planting has an important effect on wind resistance. Two rows of planting of street trees have a better utility and wind resistance, and a row spacing of 2.0~6.0 m is more appropriate. The height of the lower shrubs should be lower than the height of the first branch, with 0.5~1.0 m being more suitable. Based on the results of the data simulation and analysis, this paper proposes corresponding tree species selections and planting strategies for road green belts on Pingtan Island from the perspective of street tree species, planting parameters, and planting forms to provide references for the upgrading and planning of roadway tree landscapes on Pingtan Island as well as in similar climatic regions. [ABSTRACT FROM AUTHOR]

In this study, experimental and computational studies of the impact of forced convective flow on the heat transfer characteristics of staggered pin fins with perforations are investigated in a rectangular channel at constant heat flux with Reynolds numbers (Re) of 2 × 103–12 × 103. In particular, cylindrical pin fins with circular longitudinal (L) perforation, longitudinal/transverse (LT) perforation, and longitudinal/transverse/vertical (LTV) perforation perforations are compared to solid pin fins to find out how adding different perforation arrays affects overall heat transfer performance and also to find the best perforation configuration for maximum performance. ANSYS‐FLUENT is employed for numerical simulation, validated by experimental data. Experimental validation is conducted by attaching the heat sink to a Peltier module, inducing heat generation through current on one face in the Armfield Free and Forced Convection Heat Transfer Service Units HT 19 and HT10XC. Results highlight significant increases in Nusselt number (Nu) for perforated pins compared to solid pins, with L perforations at 8%, LT perforations at 33%, and 67% for LTV perforated pins due to transverse perforations that act as slots, which stir up the primary flow and induce secondary flow generated by vertical perforations. Regarding pressure drops, L perforations reduce by 9%, LT by 19%, and LTV by 27% compared to solid pins. The overall enhancement ratio peaks at the minimum Reynold number, notably achieving a 38% increase in the LTV perforation pin fin array. This innovative study holds promise for diverse electronic applications, offering enhanced heat transfer performance in electronic cooling systems. [ABSTRACT FROM AUTHOR]

In this paper, the effects of an ultrasonic power and the intensity of mechanical agitation for pulp on alkaline pretreatment of gold-bearing arsenopyrite were investigated. The effect of pulp temperature on leaching efficiency in alkaline pretreatment of arsenopyrite was investigated under ultrasound and non-ultrasound conditions. Pre-treatment was followed by gold leaching tests with a cyanide solution. Compared with the nonultrasound condition at the temperature of 60 ○C, arsenic extraction and gold extraction was increased 20 %, 14.4 %, respectively, in the presence of ultrasound at ambient temperature. The characteristics of the ultrasonic power level as a function of the intensity of mechanical agitation were evaluated by a numerical simulation with CFD software – Ansys Fluent. The simulation results demonstrated that the stronger intensity of mechanical agitation, the lower ultrasonic power level. These results were proved through leaching experiments at different rotation speeds of impeller and ultrasonic powers. The study results demonstrate that the ultrasound is an effective factor for pretreatment of gold bearing arsenopyrite and gold extraction is related to an ultrasonic power and the intensity of mechanical agitation. [ABSTRACT FROM AUTHOR]

Flow studies in control structures require the development of nonlinear differential equations that have no analytical solution but can be approximated by applying the finite volume method in mathematical models such as Fluent. This article presents a comparative analysis between a numerical model and a physical model of water flow in a laboratory channel using ANSYS Fluent. The scope of the study includes the development of a 2D model of the laboratory channel with a control section of a sliding flat rectangular gate and the mathematical development of the Navier-Stokes equations to model a biphasic flow of water and air throughout the computational domain, using appropriate boundary conditions. The methodology employed numerical simulation techniques using ANSYS Fluent, applying the finite volume method to solve the flow equations, and experimental techniques through direct measurements taken in the laboratory. The results demonstrate a 95.46% similarity between the mathematical modeling, direct measurements, and analytical calculations. Variables such as discharge coefficient, flow profiles, velocities at different points in the channel, and pressure distribution remained consistent throughout the computational domain. In conclusion, the advantages of the numerical model over the physical model are highlighted, emphasizing its efficiency and cost-effectiveness by allowing easy and simultaneous modifications in problem configurations, turbulence models, and boundary conditions. Additionally, the importance of the numerical model is highlighted by providing more accurate results than direct measurements made on the physical model, especially in turbulent areas and in the interaction of biphasic flow in the channel and gate. Finally, it is important to include a sensitivity analysis and mesh refinement in the mathematical model in such studies to avoid fluctuations near the gate where the section contracts. [ABSTRACT FROM AUTHOR]

The current study aims to simulate the combustion process performance inside a diesel engine and then assess the environmental impact of variable methanol ratios on maximum and operational temperatures, as well as the emission performance of a diesel/methanol dual-fuel engine. The numerical simulation for combustion is conducted on a 3-D sector cylinder using Ansys Fluent to calculate the dynamic motion of air and combustion characteristics. Subsequently, diesel/methanol dual-fuel combustion is performed to evaluate the distribution of essential mass fraction, operational temperature, and pollution inside the combustion engine, such as nitrogen oxides (NOx), sulfur oxides (SOx), and soot emissions. The study illustrates that NOx emissions from diesel/methanol, including NO and N2O, are reduced by 57% and 65%, respectively, compared with pure diesel fuel. Additionally, there is a decrease in SOx and soot pollution by 52% and 53%, respectively. The mass fraction for oxygen, hydrogen, and carbon monoxide is reduced by increasing the methanol ratio. The convergence between the Computational Fluid Dynamics and experimental results indicates the feasibility of using numerical analysis in diesel engine design. [ABSTRACT FROM AUTHOR]

In this study, the effectiveness factor correlations proposed for steam methane reforming (SMR) in Ni-based washcoat catalyst layers were numerically validated using the commercial computational fluid dynamics (CFD) software, ANSYS Fluent. The SMR process in an exemplary microchannel reformer was simulated, once by fully considering the reaction and diffusion process within the washcoat catalyst layer and again by simplifying the process calculation using the effectiveness factor correlations. It was shown that the proposed effectiveness factor correlations could successfully capture the SMR characteristics in the washcoat catalyst layer, with a discrepancy of approximately 0.1% point in the overall methane conversion ratio in the validation test, while reducing the calculation time by a factor of 1/5 for the same number of iterations. All these results clearly demonstrated that accurate and cost-effective CFD simulation of the steam reformer operation is possible using the proposed effectiveness factor correlations. Finally, this paper also addressed a possible numerical anomaly in the Fluent calculation identified during the present simulation. [ABSTRACT FROM AUTHOR]

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This paper deals with the problem of predetermining the spray angle and uniformity of the flat fan sprayer with a semicircular impact surface for the intra-soil application of liquid mineral fertilizers. The jet impact on a round splash plate and radial atomization properties are investigated theoretically, the formation features of the spray with an obtuse angle are studied in a geometrical way, and the design search of the nozzle shape and optimization calculations are performed using computational fluid dynamics (CFD) simulations and then verified experimentally. It was revealed that the spray rate and spray angle can be adjusted by changing the parameter s, and when the spray angle is within s = 0–0.2 mm, it forms spray angles with range of 140°–175°. The spraying angle, in turn, shows the potential length of the tillage knife in accordance with the undersoil cavity dimensions. A spray uniformity of up to 74% was achieved, which is sufficient for applied studies and for intra-soil application operations. According to the investigations and field experiments, it can be concluded that the designed nozzle is applicable for the intra-soil application of liquid mineral fertilizers. The use of flat fan nozzles that form a spraying band under the soil cavity and along the entire length of the tillage knife ensures a highly efficient mixing process, the liquid mineral fertilizers with treated soil (particles) positively contributing to plant maturation. [ABSTRACT FROM AUTHOR]

The paper presents a methodology that combines experimental measurements and mathematical-physics analyses to investigate the flow behavior in a nozzle-equipped aperture associated with the solution of its impact on electron beam dispersion in an environmental scanning electron microscope (ESEM). The shape of the nozzle significantly influences the character of the supersonic flow beyond the aperture, especially the shape and type of shock waves, which are highly dense compared to the surrounding gas. These significantly affect the electron scattering, which influences the resulting image. This paper analyzes the effect of aperture and nozzle shaping under specific low-pressure conditions and its impact on the electron dispersion of the primary electron beam. [ABSTRACT FROM AUTHOR]

Currently, the process of creating industrial installations is associated with digital technologies and must involve the stage of developing digital models. It is also necessary to combine installations with different properties, functions, and operational principles into a single system. Some tasks require the use of predictive modeling and the creation of "digital twins". The main processes during the fuel cell modeling involve electrochemical transformations as well as the movement of heat and mass flows, including monitoring and control processes. Numerical methods are utilized in addressing various challenges related to fuel cells, such as electrochemical modeling, collector design, performance evaluation, electrode microstructure impact, thermal stress analysis, and the innovation of structural components and materials. A digital model of the membrane-electrode unit for a solid oxide fuel cell (SOFC) is presented in the article, incorporating factors like fluid dynamics, mass transfer, and electrochemical and thermal effects within the cell structure. The mathematical model encompasses equations for momentum, mass, mode, heat and charge transfer, and electrochemical and reforming reactions. Experimental data validates the model, with a computational mesh of 55 million cells ensuring numerical stability and simulation capability. Detailed insights on chemical flow distribution, temperature, current density, and more are unveiled. Through a numerical model, the influence of various fuel types on SOFC efficiency was explored, highlighting the promising performance of petrochemical production waste as a high-efficiency, low-reagent consumption fuel with a superior fuel utilization factor. The recommended voltage range is 0.6–0.7 V, with operating temperatures of 900–1300 K to reduce temperature stresses on the cell when using synthesis gas from petrochemical waste. The molar ratio of supplied air to fuel is 6.74 when operating on synthesis gas. With these parameters, the utilization rate of methane is 0.36, carbon monoxide CO is 0.4, and hydrogen is 0.43, respectively. The molar ratio of water to synthesis gas is 2.0. These results provide an opportunity to achieve electrical efficiency of the fuel cell of 49.8% and a thermal power of 54.6 W when using synthesis gas as fuel. It was demonstrated that a high-temperature fuel cell can provide consumers with heat and electricity using fuel from waste from petrochemical production. [ABSTRACT FROM AUTHOR]

Decontamination processes in nuclear facilities require the implementation of ventilated airlocks around the contaminated equipment to prevent leakage of radioactive materials toward the surrounding environment. To ensure compliance with the recommendations of an efficient dynamic containment in nuclear facilities, which are provided by the ISO 17873 standard depending on maintenance and dismantling sites in nuclear facilities, depression must be ensured in the room where the contaminated equipments installed by using exhaust fans. This study focuses on two main objectives: first, identifying and comprehending the physical phenomena and geometric or dynamic parameters involved in the appearance of backflow of pollutants during the dynamic confinement on nuclear sites by air transfer mechanisms through openings; second, investigating and simulating the configurations and aerodynamic conditions in the vicinity of the openings that may result in the phenomenon of backflow in the case of a gaseous pollutant. Numerically simulating this occurrence will improve our capacity to comprehend, predict, and thus prevent it. The openings in which we are interested are those likely to be encountered in the airlocks of nuclear sites. These are rectangular slots with thin rigid or flexible walls. To illustrate this phenomenon, a numerical simulation is performed using the ANSYS Fluent commercial calculation code, a dynamic mesh is used to simulate a moving plate which consists in generating disturbances in the flow. The comparison of the experimental and numerical results confirms the leakage of the pollutant through the opening outside the depressurized airlock, and this only for well defined extraction velocities. Comprehension of the physical phenomena involved in the appearance of backflow of pollutants during dynamic confinement; Investigation and simulation the configurations and aerodynamic conditions in the vicinity of the openings that may cause a phenomenon of backflow in the case of a gaseous pollutant; Increasing the capacity for comprehension and prediction in order to prevent the phenomenon of backflow gaseous pollutants through simulation. [ABSTRACT FROM AUTHOR]