Computational Fluid Dynamics Analysis Research Articles

Improving the sustainability and effectiveness of photovoltaic evaporative cooling greenhouse in the Sahel.

Anthropogenic climate change has caused worldwide extreme weather events including droughts, floods and heatwaves. It disproportionately affects developing countries through food insecurity. Greenhouse is important and relevant to the food-energy-water security in many regions. This study investigates the thermal behavior of photovoltaic evaporative cooling greenhouse made with eco-friendly coolers. The cooling potential of local plant materials was assessed under ambient conditions. Experimental thermal data obtained from optimized evaporative cooling system equipped with Hyphaene thebaica fibers (HF-pad) and conventional Celdek pad (C-pad), were used in heat and mass transfer equations to derive the greenhouse cooling performances. Computational fluid dynamics analysis software was used to investigate the refrigerant fluid distribution in the greenhouse. Cooler using HF-pad allows to keep the microclimate below 25°C, with maximum moisture rate up to 80%, under harsh ambient conditions (temperature: 30-45°C, humidity: 10-15%). HF-pad had the highest cooling coefficient of performance (COP = 9 against 6 for C-pad), the best cost to efficiency ratio (CER = 5; 4 times less than C-pad) and the lowest outlet temperature (20.0°C). Due to higher outlet air velocity (1.116m/s against 0.825m/s for HF-pad), C-pad cooler spread cool air (20.5°C) up to 1.25m farther than its counterpart, creating higher pressure in the atmosphere (1.42Pa against 0.71Pa), with 2 times turbulent kinetic energy (0.014J/kg). HF-pad presented cooling performances that compete with conventional pads. Moreover, optimization of HF-pad frame engineering and the technology scaling up to industrial level can allow better thermal and economic performances.

Experimental and numerical investigation on the hydroelastic response of barge and KVLCC2 ship

In this paper, the hydroelasticity of two segmented ship models (Barge and KVLCC2) is investigated by experimental and numerical methods. A two-way Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) coupled method is adopted and further validated its accuracy against experimental results. The current approach emphasizes the overall convergence between two solvers, maintaining a strongly coupled manner to comprehensively address the fluid-structure interaction phenomenon, including the added mass effect. A series of experiments of a segmented Barge and KVLCC2 under various wave conditions were firstly conducted. The motions of the models are measured and the displacement Response Amplitude Operators (RAOs) are calculated. The CFD-FEA coupled method is demonstrated in agreement with experimental results by comparing the numerical prediction with the tank test results in terms of motion, affirming the validity and robustness. Finally, the hydroelastic response is discussed and investigated.

Numerical investigation of blunt body's resistance and heat reduction with combination of airway spike and root jet

Aerodynamic heating and impact resistance present significant challenges for hypersonic aircraft. This study introduces a novel multi-jet strategy to enhance both resistance reduction and thermal protection performance of hypersonic aircraft. Computational Fluid Dynamics (CFD) analysis is employed for the aerodynamic evaluation. The results demonstrate that this novel strategy effectively mitigates the shock waves, the peak pressure coefficient and Stanton number have been reduced by 64.3 % and 73.2 %, respectively. Through a comprehensive analysis of the influencing factors, it has been found that increasing the pressure ratio of the root jet significantly lowers the heat flux and pressure on the blunt body, albeit at the cost of an increased total flight resistance. When the nozzle on the side of the airway is oriented perpendicularly to the incoming flow direction, a notable reduction in resistance and aerodynamic heating on the blunt body is noted. By increasing the length-diameter ratio of the spike, a significant decrease in the pressure coefficient of the blunt body is achieved, the Stanton number remains largely unaffected. This study offers insights into the engineering application of strategies for reducing resistance and heat in hypersonic aircraft.

A space marching method for sonic boom near field predictions

The conventional sonic boom propagation prediction method widely adopted in supersonic aircraft design involves a two-step procedure. In the first step, a compressible viscous or inviscid Computational Fluid Dynamics analysis is applied to the aircraft geometry at flight conditions to produce a flow field solution near the aircraft. Then in the second step, a one dimensional nonlinear Burgers’ equation model is used to propagate sonic boom signature traces from the near field solution at flight altitude to the ground along a ray path. For an accurate ground signature prediction the near field signature must be accurately modeled at a sufficient distance from the aircraft flight path in order to minimize errors in the one dimensional propagation model. This is a very challenging task for general purpose CFD tools in a design environment because the cost of maintaining highly accurate off-body solutions increases dramatically as the radial distance is enlarged in the computational domain. It is also particularly difficult to apply these tools for wave propagation because the algorithms are normally lower order and numerically dissipative and dispersive. In this work a space marching procedure based on an optimized higher order finite difference method is developed and applied in conjunction with a CFD solution concentrated in the close vicinity of the aircraft. This new approach is much more efficient, compared to previous methods, in providing highly accurate near field signatures for full carpet ground predictions. Results indicate that near field signatures retain more waveform shape information farther from the aircraft geometry while reducing the CFD cost significantly. The predicted ground signature is also shown to converge in shape as the radial distance of the near field signature grows, which is indicative of a more ideal initial condition being supplied to the one dimensional wave propagation to ground. This feature is very difficult to replicate in a tractable manner with common CFD approaches used in design.

Quantitative analysis of hemodynamic changes induced by the discrepancy between the sizes of the flow diverter and parent artery

The efficacy of flow diverters is influenced by the strut configuration changes resulting from size discrepancies between the stent and the parent artery. This study aimed to quantitatively analyze the impact of size discrepancies between flow diverters and parent arteries on the flow diversion effects, using computational fluid dynamics. Four silicone models with varying parent artery sizes were developed. Real flow diverters were deployed in these models to assess stent configurations at the aneurysm neck. Virtual stents were generated based on these configurations for computational fluid dynamics analysis. The changes in the reduction rate of the hemodynamic parameters were quantified to evaluate the flow diversion effect. Implanting 4.0 mm flow diverters in aneurysm models with parent artery diameters of 3.0–4.5 mm, in 0.5 mm increments, revealed that a shift from oversized to undersized flow diverters led to an increase in the reduction rates of hemodynamic parameter, accompanied by enhanced metal coverage rate and pore density. However, the flow diversion effect observed transitioning from oversizing to matching was less pronounced when moving from matching to undersizing. This emphasizes the importance of proper sizing of flow diverters, considering the benefits of undersizing and not to exceed the threshold of advantages.

Experimental Analysis of Heat Transfer Post Quenching of Medium Carbon Steel

<div>Transient temperature analysis is involved in the thermal simulation of the heat treatment process, in which the hot metal temperature changes with respect to time from an initial state to the final state. The critical part of the simulation is to determine the heat transfer coefficient (HTC) between the hot part and the quenching medium or quenchant. In liquid quenching, the heat transfer between the hot metal part and water becomes complicated and it is difficult to determine HTC. In the current experimentation a medium carbon steel EN 9 rod with a diameter of 50 mm and length 100 mm was quenched in water and ethylene glycol mixture with different concentrations. A part model was created; meshed and actual boundary conditions were applied to conduct computational fluid dynamics (CFD) analysis. In order to validate CFD analysis the experimental trials were conducted. Experimental results showed a reduced cooling rate for the specimen, and also a reduction in heat-carrying capacity of the mixture, which is attributed to the addition of ethylene glycol.</div>

Design and Analysis of Fugitive Dust Emission Collector

This creative project explores the design and analysis of a novel fugitive dust emission collector, with a focus on its application in stone crusher units and crematorium facilities. Recognizing the detrimental health and environmental impacts of dust emissions, this project proposes a multifaceted approach. The core solution involves a combined system, this captures and removes larger dust particles through established methods like cyclones or bag houses. Dry fog dust suppression system, this technology utilizes atomized water droplets to suppress smaller fugitive dust particles, preventing their airborne spread. This project delves into the specific needs of stone crusher units and crematorium facilities. Utilizing CAD software, 3D models of the emission collector will be created, incorporating considerations like material selection, efficiency and airflow optimization, integration with existing infrastructure. Computational fluid dynamics (CFD) analysis by Simulating airflow patterns and dust capture efficiency within the collector. Assessing the collector's ability to withstand operational loads and environmental factors. This project aims to achieve, reduced fugitive dust emissions, enhanced environmental compliance, improved operational efficiency. Overall, this creative project showcases an innovative approach to fugitive dust control, potentially leading to improved environmental and public health outcomes in diverse industrial settings

Satellite Thermal Management Pump Impeller Design and Optimization

This study presents a numerical approach to the design and optimization of centrifugal impellers used in the pumps of active thermal control systems of spacecraft. Although launch costs have shrunk in the last decade, the performance requirements, such as efficiency and reliability, have increased, as such systems are required to work up to 15 years, depending on the mission. To that effect, our paper deals with the first step in this pump design, namely the hydraulic optimization of the impeller. Constructively, this type of impeller allows for certain balancing systems and labyrinth seals to be applied in a more effective way, as well as allowing for additive manufacturing methods to be used—however, details regarding these aspects are beyond the scope of the current paper. By combining empirical formulas, computational fluid dynamics (CFD) analysis, and artificial neural networks (ANNs), the research focuses on achieving high efficiency and fast manufacturing. A series of geometries have been sized and validated using steady-state RANS (Reynolds Averaged Navier-Stokes) simulations, leading to the identification of the most efficient configuration. Subsequent optimization using an ANN resulted in a refined impeller design with notable improvements in hydraulic performance: a 3.55% increase in efficiency and a 7.9% increase in head. Key parameters influencing impeller performance, including blade number, incidence, and backsweep angles, are identified. This approach offers a comprehensive method to address the evolving requirements of space missions and contributes to the advancement of centrifugal pump technology in the space domain.

CFD and Wind Tunnel Study on Cricket Ball at Different Seam Angle and Velocity

This study delves into the intriguing investigation of flow patterns over a cricket ball, employing both computational and experimental methods for a comparative analysis. The work explores about variation of velocities in different angles, here we have used as 4 cricket balls they are dukes cricket balls, SG cricket balls, dukes 3d printed cricket ball and SG printed cricket ball. While comparing all the cricket balls it shows values in the wind tunnel experiment in seam angles of 0°,30°,45°,60°& 90° in a subsonic wind tunnel. Both computational simulations and experimental observations were conducted to analyze the impact of seam angles and velocities on the cricket balls. The results obtained from computational models were successfully validated through experimental data, affirming the reliability of the computational approach in predicting aerodynamic characteristics. Flow visualization techniques further confirm these findings, highlighting the significance of keywords such as drag, seam angles, reverse swing, flow visualization, and computational fluid dynamics (CFD) in understanding the aerodynamics of cricket balls. Overall, this research provides valuable insights into optimizing bowling strategies by considering the interaction between seam angles, velocities, and aerodynamic behavior of cricket balls. Keyword: Ball drag analysis, Reverse swing analysis, CFD analysis, Cricket ball analysis.

Experimental and Numerical Study of the Flow Around Rigid and Flexible Hydrofoils for Wetted and Cavitating Flow Conditions

Abstract The hydro-elastic response of a flexible NACA 0015 hydrofoil is investigated for both wetted and cavitating flow conditions. Computational fluid dynamics (CFD) analysis are performed using a fully implicit coupling between the ISIS-CFD solver (developed by the METHRIC team at Ecole Centrale de-Nantes) and a modal approach for the structure. The Reynolds-averaged Navier–Stokes (RANS) solver is first validated for wetted and cavitating flow conditions around a similar rigid hydrofoil, with experimental results carried out at the hydrodynamic tunnel of the French Naval Academy, including lift and drag measurements and high speed camera images. Then the numerical predictions for the flexible hydrofoil response are compared with experimental bending shapes and vibrations amplitudes, with a focus on cavitating flow conditions. For wetted flow conditions, numerical results show a good agreement with the experiments, for both rigid and flexible hydrofoils. For cavitating flow conditions, the hydro-elastic response is dominated by vibrations at the hydrofoil modal frequencies and the reentrant jet instability frequency. For the lowest values of the cavitation number, a large amplitude peak is experimentally observed in the frequency response spectra, due to lock-in between the first modal frequency and the reentrant jet frequency. Strong harmonics of this dominant peak also appear in the spectra, revealing a nonlinear response of the hydrofoil. While the amplitudes of vibrations are well predicted by the computations, the frequency lock-in observed in the experiments is not captured by the numerical model.

Study of Orifice Design on Oleo-Pneumatic Shock Absorber

Aircraft oil-strut shock absorbers rely on orifice designs to control fluid flow and optimize damping performance. However, the complex nature of cavitating flows poses significant challenges in predicting the influence of orifice geometry on energy dissipation and system reliability. This study presents a comprehensive computational fluid dynamics (CFD) analysis of the effects of circular, rectangular, semicircular, and cutback orifice profiles on the internal flow characteristics and damping behavior of oleo-pneumatic shock absorbers. High-fidelity simulations reveal that the rectangular orifice generates higher damping pressures and velocity magnitude than those generated by others designs, while the semicircular shape reduces cavitation inception and exhibits a more gradual pressure recovery. Furthermore, the study highlights the importance of considering both geometric and thermodynamic factors in the design and analysis of cavitating flow systems, as liquid properties and vapor pressure significantly impact bubble growth and collapse behavior. Increasing the orifice length had a negligible impact on damping but moderately raised orifice velocities. This research provides valuable insights for optimizing shock absorber performance across a range of operating conditions, ultimately enhancing vehicle safety and passenger comfort.

Computational Fluid Dynamics (CFD) Analysis of Bioprinting.

Regenerative medicine has evolved with the rise of tissue engineering due to advancements in healthcare and technology. In recent years, bioprinting has been an upcoming approach to traditional tissue engineering practices, through the fabrication of functional tissue by its layer-by-layer deposition process. This overcomes challenges such as irregular cell distribution and limited cell density, and it can potentially address organ shortages, increasing transplant options. Bioprinting fully functional organs is a long stretch but the advancement is rapidly growing due to its precision and compatibility with complex geometries. Computational Fluid Dynamics (CFD), a carestone of computer-aided engineering, has been instrumental in assisting bioprinting research and development by cutting costs and saving time. CFD optimizes bioprinting by testing parameters such as shear stress, diffusivity, and cell viability, reducing repetitive experiments and aiding in material selection and bioprinter nozzle design. This review discusses the current application of CFD in bioprinting and its potential to enhance the technology that can contribute to the evolution of regenerative medicine.

Hydro-mechanical analysis of particle migration in fractures with CFD-DEM

Particle migration driven by fluid flow is presented in many geological and geotechnical contexts, such as sand production in oil exploitation, internal erosion in dikes or dams, and proppant movement in petroleum engineering. In this study, fluid flow-induced particle migration in rock fractures has been investigated by coupling the computational fluid dynamics (CFD) and the discrete element method (DEM), focusing on the particle movements and the associated migration mechanisms. To fit the fracture roughness, tetrahedral grids were used to generate the fluid mesh in CFD analysis. The CFD-DEM model was first calibrated against experimental and analytical results, then a series of simulations was conducted to analyze the effects of fracture roughness (defined by the joint roughness coefficient, JRC), size ratio between fracture aperture and particle diameter, and hydraulic gradient on the migration of particle assemblies. Three modes of particle movement were obtained, i.e., the movement of particle assemblies as a whole, the separation of large particle assemblies into smaller ones, and the detachment of particles at assembly boundaries. Additionally, the velocity of a particle assembly passing through the fracture was negatively related to the aggregation of particles while positively related to the erosion rate of particle assemblies within the fracture. An equation to calculate the time of a particle assembly to pass through a fracture was proposed.

Investigation of the use of new fin on the melting time of the phase change material stored in the heat exchanger by computational fluid dynamics analysis

Investigation of the use of new fin on the melting time of the phase change material stored in the heat exchanger by computational fluid dynamics analysis

NUMERICAL HEAT TRANSFER ENHANCEMENT OF SOLAR RECEIVER TUBE OF PARABOLIC TROUGH COLLECTOR USING FIBERFRAX 140 COATED WITH AL 2O 3

Parabolic trough collectors (PTCs) play a vital role in solar-thermal energy conversion, with the absorber tube being central to heat collection efficiency. This study investigates the potential for improving heat transfer within the PTC absorber tube using Fiberfrax 140 coated with Al 2O 3 as a novel reflector material. The research is driven by the ongoing pursuit of enhanced PTC performance. A standard modeling approach was employed, utilizing Computational Fluid Dynamics (CFD) analysis with SolidWorks Flow Simulation software, coupled with solar simulations to assess collector performance under varying conditions. Environmental parameters of Bauchi such as temperature, humidity, and wind speed were sourced from the Nigerian Meteorological Agency (NiMet). Optimization techniques were implemented to establish the optimal design configuration. The optimal design parameters were determined as a focal length of 700mm and a rim angle of 90°. Simulations were conducted daily from 8:00 AM to 5:00 PM, encompassing the period of January to June. A mass flow rate of 0.2 kg/s, informed by existing literature, was employed in the simulations. The results indicate improved collector performance throughout the simulated period, with peak thermal efficiency ranging from70%to82%.

Modelling of aero-mechanical response of wind turbine blade with damages by computational fluid dynamics, finite element analysis and Bayesian network

Computational Fluid Dynamics and Finite Element Analysis structural models are developed for generation of large datasets of high-fidelity aerodynamic loading, displacement and stress for the NREL 5 MW wind turbine blade. Based on the datasets, analysis of structural responses of the turbine blade and their possible shifts with respect to a change in the operating conditions, e.g. rotor plane tilting and yawing, are performed. A Bayesian Network model is trained to produce ranges of values and likelihoods of occurrence of abnormal structural response or the most likely damage in the blade from inputs of operating conditions. The numerical analysis showed that yawing and tilting of rotor plane has very strong influence on the performance of a wind turbine. The out-of-plane bending is the dominant mode of the rotor blade while twisting and other complex modes of displacement could be more significant during some operating conditions such as at high tilt and yaw angles. The Bayesian Network is capable of computing probability mass functions of mechanical stress or displacement of the blade given a rotor rotation speed and a type of damage or vice versa, identifying a type of damage given a measured stress distribution level.

Computational Fluid Dynamics Analysis of Latent Heat Recovery Employed with Teg Module and Waste Heat Recovery from Automobile Radiator

Abstract: Providing good and best solutions to everyday problems varies day by day with the evolving technologies. The solution pertaining to the problemsassociated with the exhaust gases from the automobile or other such equipment‘s revolves around only on the ways of reducing the pollution. Many designs and developments are also made in terms of alternative energies at low cost. One such ideology is to recover and reuse the energy that is exhibited out in the form of liquid or heat. Waste heat recovery will be a new energy source. Thermal fluid flow heat recovery system fromAutomobile radiator with internal and external tubes is one such option While most of the state of art papers considers only the waste heat as energy source, this thesis discusses the usage of phase changing materials in the external fluid flow tubes in heating and cooling paths. Both the static and dynamic nature of the energy is used in the work.

Investigation of Ventilation Performance to Improve the Indoor Air Quality of Institutional Kitchens

Indoor Air Quality (IAQ) is a significant health determinant in the building environment. Ventilation plays a significant role in providing comfortable working conditions and securing contaminant removal from indoor spaces. The heat and effluents generated by cooking activity need to be exhausted from the kitchen space to control the IAQ and provide thermal comfort. The study investigates the ventilation performance concerning IAQ of five institutional kitchens in an educational campus. This study evaluates the influence of building parameters on ventilation performance and IAQ using experimental research and Computational Fluid Dynamics (CFD). The empirical part includes field measurement of indoor airflow and IAQ indicators (particulate matter, CO2, temperature, and RH). The Integrated Environmental Solutions Virtual Environment (IESVE) software performs the CFD analysis. The 'Local Mean Age of air' (LMA) is used as a parameter to analyze IAQ. The findings reveal that the LMA reduces with increased cross-ventilation at the operational level and the presence of local exhaust ventilation, such as chimneys. Moreover, a higher slenderness ratio, lower aspect ratio, and lower building volume reduce the age of air.

Function of flow wakes for queuing trilobites: Positioning rather than drag reduction – Criteria for drag force assessment in palaeontological CFD simulations

Trilobites are one of the most important invertebrate clades in the Palaeozoic, with significant disparity in morphology and behaviour, the latter including intriguing instances of queueing. Previous studies employed Computational Fluid Dynamics (CFD) to investigate queuing behaviour in the Devonian trilobite Trimerocephalus chopini and found drag reduction effects. Novel calculations that define a ratio between drag force and Apparent Gravity (W), along with the Submerged Froude Number (Frsub), however, reveal that the obtained drag force was practically negligible in terms of the underwater mobility of trilobites. A trilobite would start to experience difficulty in forward walking only when the relative flow speed was over 42 cm/s, which is inconsistent with the interpreted palaeoenvironment or the predicted moving speed of trilobites. Nevertheless, according to the proposed cantilever model, a trilobite had the ability to sense very minute change in fluid velocity (>7.16 μm/s). High-sensitivity mechanical sensors distributed along the body, either on the exoskeleton or limbs, empowered queuing individuals to discern the fixed self-similar pattern of the wake generated by their predecessors in the queue. In general, if a trilobite were out of the wake, the asymmetrical velocity and pressure field would aid in repositioning itself, facilitating the maintenance of migratory queues. This permitted blind trilobites to securely sense their companions, compensating for lack of long-range visual capability. This paradigm of force assessment is suitable to Computational Fluid Dynamic analyses in other extinct animal-environment interactions, offering a framework to evaluate whether drags and wakes impact more on organism's mobility (W≫0.1,Frsub≫1) or their mechanical sensors, and provides a unique cross-scale insight into animals' adaptation to palaeohydrodynamic variation.

Computational fluid dynamics analysis of the fluid environment of 3D printed gradient structure in interfacial tissue engineering

Mass transport properties within three-dimensional (3D) scaffold are essential for tissue regeneration, such as various fluid environmental cues influence mesenchymal stem cells differentiation. Recently, 3D printing has been emerging as a new technology for scaffold fabrication by controlling the scaffold pore geometry to affect cell growth environment. In this study, the flow field within scaffolds in a perfusion system was investigated with uniform structures, single gradient structures and complex gradient structures using computational fluid dynamics (CFD) method. The CFD results from those uniform structures indicate the fluid velocity and fluid shear stress within the scaffold structure increased as the filament diameter increasing, pore width decreasing, pore shape decreased from 90° to 15°, and layer configuration changing from lattice to stagger structure. By assembling those uniform structure as single gradient structures, it is noted that the fluid dynamic characterisation within the scaffold remains the same as the corresponding uniform structures. A complex gradient structure was designed to mimic natural osteochondral tissue by assembly the uniform structures of filament diameter, pore width, pore shape and layer configuration. The results show that the fluid velocity and fluid shear stress within the complex gradient structure distribute gradually increasing and their maximum magnitude were from 1.15 to 3.20 mm/s, and from 12 to 39 mPa, respectively. CFD technique allows the prediction of velocity and fluid shear stress within the designed 3D gradient scaffolds, which would be beneficial for the tissue scaffold development for interfacial tissue engineering in the future.