Computational Fluid Dynamics Software Research Articles

Impact of buildings’ configuration in an urban context on the spread pattern of NO2 and indoor air quality: A CFD simulation

The influence of the building’s configuration on the air flow pattern and the amount of pollutant entering the buildings was investigated. Six common forms of low-rise buildings in Shiraz City were evaluated as investigated patterns. Each of these forms were placed in four rotation modes (24 case studies in total) in an urban regular pavilion-shaped context, placed in the vicinity of an urban highway (as a source of pollutant production) and were simulated using Computational Fluid Dynamics (CFD). In this research, air velocity and NO2 concentration were considered as the air quality parameters. Steady 3-dimensional flow was used to simulate these cases using the SST k-[Formula: see text] turbulence model, which was numerically solved based on the Reynolds-averaged Navier–Stokes (RANS) equations. The CFD software used in this research was validated in comparison with wind tunnel tests and acceptable results were found. The TOPSIS multi-criteria decision-making method was used to choose the best case based on increasing the air velocity and decreasing amount of pollutant inside the building. The results show that the best and worst building forms are related to the step-shaped and the L-shaped form, respectively. The results of this research provide design solutions for architects and urban designers to improve the ventilation quality of buildings.

Numerical and experimental studies on propulsion performance of a novel tandem paddles propulsor

Normally, small unmanned vessels used to clean floating litter on water adopt a paddle wheel as a propulsor to satisfy its shallow-draft requirements; however, this type of propulsor has bulky structures and inefficient propulsion. In this study, a novel tandem paddles propulsor (TPP) was developed, and its propulsion performance was analyzed and compared with that of a paddle wheel propulsor (PWP). Using the RNG k-ε turbulence model and sliding grid technique, the hydrodynamic performance of the PWP was simulated in computational fluid dynamics (CFD) software to verify the reliability of the numerical method. Subsequently, the propulsion performances of the two types of propulsors were simulated with different immersion depths and advanced coefficients, and the differences in their mechanical characteristics and flow field evolution were discussed and compared. The results indicate that the proposed TPP generates 2.75 times more thrust and 1.99 times greater efficiency than the PWP, exhibiting superior propulsion capability in shallow-draft vessels.

Numerical study of external explosion in vented hydrogen explosions

In the current study, numerical study of vented hydrogen explosions was performed utilizing computational fluid dynamics (CFD) software GASFLOW-MPI. A turbulent combustion model based on Schmidt correlation was formulated. Within this model, flame instabilities resulted from two intrinsic effects, Hydrodynamic instability, and Landau-Darrieus and Thermal-Diffusive instabilities were incorporated. The numerical simulation results revealed the mechanism of overpressure evolution inside and outside the vessel. Notably, the mechanism of the overpressure peak induced by the external explosion was revealed. The effects of turbulence models on overpressure time profiles were investigated. Moreover, it was determined that heat transfer, arising from thermal radiation and convection, exerts only a negligible influence on the maximum internal overpressure. Subsequently, the performance of GASFLOW-MPI in simulating vented hydrogen explosions for different ignition locations (center and rear ignitions) and varying hydrogen concentrations (22%-38%) was assessed against experimental data. Comparative analysis revealed a close agreement between the predicted results and experimental data. Furthermore, the competency of GASFLOW in simulating medium-scale vented hydrogen explosions was validated against experimental data.

Design and Analysis of a Vertical Axis Ocean Current Turbine Tunnel Using SolidWorks Computational Fluid Dynamics

The development of renewable energy in the marine power generation sector presents a promising approach to producing electrical energy in a sustainable and environmentally friendly manner. Indonesia, with its vast oceanic territory, holds significant potential for harnessing marine energy. However, the relatively slow speed of ocean currents in the region, typically ranging from 0.1 m/s to 1.5 m/s, poses a challenge to the efficiency of marine power generation. To overcome this limitation, this research focuses on the design and analysis of a vertical-axis ocean current turbine tunnel aimed at increasing the speed of ocean currents, thereby enhancing the overall efficiency of energy production. The study combines a thorough literature review with experimental research methods, utilizing SolidWorks Computational Fluid Dynamics (CFD) software to simulate the tunnel's impact on ocean current velocity. The simulations reveal that the tunnel construction significantly boosts current speeds, increasing them from 1.0 m/s to 1.7 m/s, and from 1.5 m/s to 2.6 m/s. This increase in velocity directly translates to higher kinetic energy available for conversion into electrical power by the turbine. Moreover, the study shows that the tunnel construction contributes to a more uniform flow of ocean currents, as evidenced by the Reynolds numbers obtained—100.250 at a current speed of 1.0 m/s and 150.375 at 1.5 m/s. These values, being below 2000, indicate laminar flow conditions within the tunnel, which are beneficial for optimizing turbine performance by reducing turbulence and ensuring a stable energy output. The findings underscore the effectiveness of the tunnel design in improving the efficiency of vertical-axis ocean current turbines, making it a viable solution for enhancing renewable energy production in regions with low ocean current speeds.

Coupled analysis of floating offshore wind turbines with new mooring systems by CFD method

This paper presents a fully coupled aero-hydro-mooring numerical model of the National Renewable Energy Laboratory's (NREL) 5 MW OC4 semi-submersible Floating Offshore Wind Turbine (FOWT). The model's accuracy was validated through comparisons with existing experimental and numerical data, utilizing OpenFOAM, a Computational Fluid Dynamics (CFD) software. The key contributions of this study include demonstrating the model's precision in predicting aerodynamic performance, motion responses, and mooring system dynamics under wind and wave conditions. Additionally, a comparative analysis is conducted between a Conventional mooring system (CMS) and a New mooring system (NMS). The results show that the NMS offers improved stability in surge and heave motions, crucial for operational effectiveness and resilience. Furthermore, the NMS demonstrates a more efficient stress distribution and also reduced tensions in the mooring lines, contributing to the long-term durability and safety of the structure. In terms of aerodynamic performance, the differences between the two mooring systems are limited due to the combined surge and pitch motion phase difference. Future research will focus on optimizing these phase differences to enhance performance and refine the cost-efficiency of the mooring system.

Experimentally Validated Potential Theory Approach for Investigation of the Flow Field Structure of an Open Pool of a Nuclear Reactor

Detailed information on the flow field structure is often important in numerous industrial applications. Although commercial computational fluid dynamics packages are often capable of providing the required data, they are costly and not universally available. This study was motivated by the operation of an open-pool nuclear research reactor where low radiation levels can be maintained by the installation of a stable purified hot water layer in the upper part of the pool. Maintaining a stable stratification requires a detailed description of the structure of the velocity field. Due to the inherent complications and restrictions of performing accurate measurements in a pool of a real-size operating reactor, either smaller-scale models or oversimplified fluid dynamics computational schemes are routinely used. These methods cannot be validated, and therefore do not necessarily capture the large-scale behavior correctly. We present an alternative approach to evaluate the velocity components in the pool that is based on the potential flow theory. The model results are validated by measurements using particle image velocimetry. The presented potential theory allows for the quick and easy assessment of the global properties of the fluid velocity distribution within the pool, and in particular, close to its surface. The suggested computational models are flexible and allow for easily varying the spatial dimensions of the flow field. The technique thus can be upscaled, and enables the validation of numerical computations in various fluid mechanical installations where the flow field cannot be resolved.

Experimentation and simulation of gas flow field distribution during the growth of carbon nanotubes in a horizontal reactor

Carbon nanotubes (CNTs) were grown in a horizontal reactor by chemical vapor deposition, and it was found in the experiments that different heating temperatures and the position of the porcelain boat affect the morphology and yield of CNTs. Computational fluid dynamics (CFD) software is used to simulate the gas flow field distribution in the horizontal reactor under different operating parameters, and the results revealed that the gas flow in the horizontal reactor was advancing with vortex, and this gas circulation is induced by the difference in density due to the existence of temperature difference between the gas streams. As the heating temperature and nitrogen gas velocity increase, this vortex distorts the laminar flow, which in turn weakens the growth of CNTs.

Improving the scour-resistance performance of for offshore wind turbines: Experimental and computational fluid dynamics studies on macro and micro characteristics

To enhance the resistance to local scour around offshore wind turbine monopiles, 15 mixtures were designed based on Response Surface Methodology (RSM). Cement content, sodium silicate content, and rubber powder content were selected as independent variables. After determining their flowability, the compressive strength and shear strength were measured after curing in pure water and artificial seawater for 3 days, 7 days, 14 days, and 28 days. Experimental results indicate significant improvement in the mechanical properties of the modified soil, including increased Unconfined Compressive Strength (UCS), internal friction angle, and cohesion. The optimal mix ratio is identified as CSR40–10–15, consisting of 40 % cement, 10 % sodium silicate, and 15 % rubber powder. The strength variation mechanism is elucidated from both macroscopic and microscopic perspectives. Finally, numerical simulations using Computational Fluid Dynamics (CFD) software validate the scour resistance performance based on the optimal mix ratio of flowable solidified soil, offering a new approach for local scour protection around offshore wind turbine monopile.

Dynamic energy optimization strategy to provide appropriate thermal comfort and fresh air under occupants’ different activity types

An effective strategy for optimizing indoor air distribution in stratum ventilation heating systems under different types of human activity has been proposed, in order to provide appropriate thermal comfort while exploiting the potential for energy savings. The stratum ventilation was optimized using strategy 1 (the optimization strategy of three ventilation performance indicators based on VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR)), the strategy 2 (the optimization strategy with constraint based on VIKOR) and the strategy 3 (the optimization strategy aimed at energy conservation), respectively. These strategies provide optimal indoor air distribution within a stratum ventilation system that is influenced by various factors (i.e. supply air temperature, supply air vane angle, supply air velocity, metabolic rate, clothing insulation and outdoor air temperature). Firstly, the parameters of the stratum ventilation system are obtained using Computational Fluid Dynamics (CFD) software. In addition, using the simulation results as input variables, predictive models of ventilation performance (i.e., PMV, local mean air age (LMAA) and energy consumption) was developed using Artificial Neural Network (ANN). Finally, by optimizing the proposed ANN based strategy 1, strategy 2 and strategy 3, the ventilation performance is output. The proposed strategy 1 provides a comfortable indoor environment and saves energy, and compared to the strategy 1, the strategy 3 saves more energy while ensuring that thermal comfort meets the requirements. In addition, considering the optimization of clothing insulation while providing appropriate thermal comfort also indirectly saves energy. Moreover, these strategies also work well as the outdoor air temperature changes.

Investigation of the dynamic and thermal performance of kinetic-static mixers: a numerical simulation study

In this paper, a numerical simulation was carried out to investigate the dynamic and thermal behaviors of various shapes of a kinetic static mixer. Three-dimensional model of the static mixer was designed using commercial Computational Fluid Dynamics (CFD) software, CFX 18.2. To examine the mixer's performance, five parameters have been considered including Re, Shear stress rate, Nu, fluid temperature and pressure drop. The fluid velocity was characterized by Reynolds numbers varying from 10 to 100, pressure drop, and shear rate has been considered for evaluating dynamic performance. Furthermore, fluid temperature and the Nusselt number was examinate to gain insights into thermal characteristics. In this study, the effectiveness of four different mixer shapes was evaluated. The outcomes underlined the significant impact changes in mixing geometry can have on the fluid's dynamic behavior, which in turn affects thermal performance. Notably, among the suggested mixer shapes, case three shows best mixing performance. This study offers significant knowledge about the dynamic and thermal behavior of kinetic static mixers, emphasizing the critical function of shape in raising overall performance.

Research on Hydrodynamics of Trans-Media Vehicles Considering Underwater Time-Varying Attitudes

A trans-media vehicle is a new type of equipment that can adapt to two environments, water and air, to maintain optimal hydrodynamic and aerodynamic performance. However, no matter what kind of trans-media vehicle, its dynamics are much more complicated when traversing the interface of the medium, as the parameters are time-varying due to the change in ambient medium and vehicle attitudes. In order to improve the stability and performance of the trans-media vehicle in complex environments, an accurate mathematical model is established to characterize the dynamics of the trans-media vehicle in this process in this study. The time-varying hydrodynamic coefficients with different attitudes or depths are obtained using computational fluid dynamics software. The mathematical model is solved iteratively using a Runge–Kutta solver to calculate the dynamic response. A prototype of trans-media vehicle is fabricated, and motion experiments are performed in the pool. The experimental results confirm the effectiveness of the established model and lay the foundation for further controller design, providing a reference for the dynamic modeling of other similar equipment operating in complex environments. The primary novelty of this study lies in the fact that the established dynamic model considers the complex interaction between the attitude of the trans-media vehicle and the inherent different properties of water and air and utilizes computational fluid dynamics software to accurately obtain time-varying coefficients under different attitudes and depths. This approach not only recognizes the criticality of orientation-dependent hydrodynamic coefficients but also incorporates their temporal variations, which were often overlooked in previous studies.

Investigating the growth of surface crack and high cycle fatigue in surface-piercing propeller

In this study, the progress of surface crack and high cycle fatigue of the surface piercing propellers (SPPs) are investigated numerically using the finite element method. The cyclic load is calculated from the hydrodynamic pressure on the blade by simulating the fluid around the blade using the computational fluid dynamics software STAR-CCM+. The initial cracks are assumed to be created near the blade root. The fatigue life is calculated from the Paris-Erdogan equation. The results show that the crack close to the root has a shorter life and the stresses at the crack front depend on the blade-water interaction duration.

A fully-coupled analysis of the spar-type floating offshore wind turbine with bionic fractal heave plate under wind-wave excitation conditions

As shallow coastal areas for the installation of wind turbines approach saturation, wind turbines will need to be installed in deeper areas, requiring floating rather than seabed-fixed substructures. Considering factors such as economy and safety, floating offshore wind turbines (FOWTs) have become the major focus for offshore wind research and development. In the case of spar-type FOWTs, stability in the heave direction poses a challenge. With this in view, in this work a heave plate with bionic fractal structures is mounted on the bottom of the spar-type FOWT. The bionic fractal heave plates are innovatively proposed to further improve the dynamic response of the FOWT. In this study, the aero-hydro-mooring dynamic method of the FOWT is established to develop a reliable numerical solution model through the DFBI module using computational fluid dynamics software STAR-CCM+. The results of fully-coupled simulations of the original FOWT, the FOWT with heave plate (HP-FOWT) and FOWTs with 3∼5-layer bionic fractal heave plate (3∼5BFHP-FOWTs) are presented. Increases in average thrust and power of 0.44 % and 0.99 %, respectively, prove the optimal aerodynamic responses of the 5 BFHP-FOWT. As for the hydrodynamic responses, the average heave response amplitudes of the HP-FOWT and 3∼5BFHP-FOWTs are significantly lower than the original FOWT. The maximum reduction (25.03 %) is obtained by the 5BFHP-FOWT. The bionic fractal heave plate will slightly reduce the stability of the pitch response. For the standard deviation of the heave, surge, mooring lines 1 and 2 responses, the 5BFHP-FOWT decreases by 17.97 %, 11.44 %, 17.50 %, and 8.25 % respectively, showing the best stability improvement among the HP-FOWT and BFHP-FOWTs. Furthermore, the vortices in the bionic fractal heave plates are analyzed in detail at the Z = ±0.25 m section of the flow field. Only when the specific fractal layer number is 5, the number and curl of the vortices in the fractal structure increase significantly, showing excellent effect of the energy absorption.

Numerical analysis of the impact of helical-blade design on flow characteristics and energy utilization in vertical-axis water turbine

In this study, a vertical-axis helical-blade water turbine is innovatively proposed by drawing on the design scheme of the traditional straight-blade turbine, compared to which this blade form can effectively improve the self-starting capability and energy capture efficiency of the turbine. The study analyzes the hydrodynamic performance of the device under different parameters using CFD (computational fluid dynamics) software STAR-CCM+ and overlapping mesh technique, and the CFD simulation results are verified with published experimental work. First, the design concept of the hydraulic turbine is presented, focusing on the design of the blades and transmission mechanism to ensure the stability of the structure. Second, the effect of two-dimensional parameters on the flow field characteristics and efficiency is investigated, and then three-dimensional design parameters, such as blade helix angle and hub-to-tip ratio, are considered. The results show that a 20% increase in blade density results in a 10.74% increase in efficiency. Regarding flow velocity, a maximum output of 2.4 kW was achieved for four operating conditions (1.0, 1.5, 2.0, and 2.5 m/s). In addition, the average dynamic torque of the helical-blade turbine was 16.44% higher than that of the straight-blade turbine, indicating superior self-starting capability. It was also found that at an aspect ratio of 1.5–1.75 and a helix angle of 80°, the energy capture efficiency of the helical-blade turbine was 33.7%, which was 45.3% higher than that of the straight-blade turbine. Comparative analysis shows that the vertical-axis helical-blade turbine has favorable hydrodynamic performance, especially under low flow conditions, and the design scheme shows obvious advantages, which makes up for the defects of the traditional vertical-axis straight-blade turbine with poor self-starting ability and low efficiency, and fills up the research gaps of vertical-axis turbine design optimization, which is of certain research value.

Multi-objective optimization of a non-uniform sinusoidal mini-channel heat sink by coupling genetic algorithm and CFD model

Wavy mini-channel heat sinks (MCHS) can disrupt the development of the thermal boundary layer, resulting in superior performance compared to straight MCHS. For complete utilization of the coolant, this study proposed and optimized a non-uniform sinusoidal MCHS with varying wavelength or varying amplitude along the flow direction. The optimization for five design variables was accomplished through a multi-objective genetic algorithm, where the thermal resistance θ or the pressure drop Δp were defined as two objectives. The computational fluid dynamics (CFD) software was employed to solve all direct problems encountered during the evolutionary process. Compared to the straight MCHS with different channel widths, the optimal designs achieved reductions of 27.74 % in θ or 59.51 % in Δp. Simultaneously, all the optimal values of the wavelength ratio and amplitude ratio indicate that enhancing the heat transfer performance downstream is more efficient. It was observed that among the five design variables, the number of wave cycles is the most relevant parameter with a Spearman’s correlation up to 0.983. Subsequently, a multiple-criteria decision-making approach was employed to ascertain the best compromise solution to balance the two objectives. Although the θ of the best compromise solution could be higher by 38.57 % than that of the lowest θ solution, the Δp presents a more substantial reduction of 92.45 % after the trade-off. Compared to the straight MCHS with the same Δp, the best compromise solution with varying wavelength reduces the θ and the standard temperature deviation by 26.20 % and 76.98 % respectively, while lowering the average base temperature by 3.07 K. Therefore, the optimal non-uniform wavy MCHS, along with the optimization approach presented, is meaningful for practical applications.

Numerical simulation of dust deposition characteristics of photovoltaic arrays taking into account the effect of the row spacing of photovoltaic modules

Dust deposition on the surfaces of Photovoltaic (PV) arrays during their operation markedly affects their power generation efficiency. Previous research has overlooked the impact of the row spacing of PV modules on the actual dust deposition on PV arrays. This study investigates the dust deposition process and its behavior on PV arrays considering variations in row spacings, inlet wind speeds, dust particle sizes, and dust particle counts. By employing commercial Computational Fluid Dynamics (CFD) software, incorporating the SST k-ω turbulence model and discrete particle model, numerical simulations were performed to analyze the airflow field, dust particle trajectories, dust deposition patterns, and deposition rates on the PV array through grid-independent verification and numerical validation. At the same time, we performed a comparative analysis of the deposition rate considering the rebound of dust particles on the PV module surface versus the case where rebound is not considered. Results revealed that the maximum dust deposition rates at different inlet wind speeds were 6.84 %, 8.84 %, 11.0 %, and 14.6 %, corresponding to dust sizes of 50 μm, 100 μm, 120 μm, and 300 μm, respectively. Smaller dust particles exhibited lower deposition rates, while larger particles were influenced more by mass inertia and gravity, leading to predominant deposition on the front row of PV modules. Larger dust particles are more likely to deposit primarily on the front row of PV modules in a PV array. The tilt angles of 30°, 45°, and 60° were chosen to study the effects of different tilt angles on the dust deposition of PV arrays, and the results show that the dust deposition rate decreases as the tilt angle increases, and it is worth noting that the larger the tilt angle, the larger the dust deposition rate is when the dust particles are especially small as 5 μm. When wind speeds are low and dust particles are small, the dust deposition rate gradually rises as the row spacing increases. However, at higher wind speeds with small dust particles, the row spacing has minimal impact on the dust deposition rate. Conversely, with larger dust particles, increasing the row spacing results in a lower dust deposition rate. These findings underscore the significance of optimizing PV array design for enhanced power generation efficiency.

CFD-Powered Ship Trim Optimization: Integrating ANN for User-Friendly Software Tool Development

This study presents a comprehensive approach to trim optimization as an energy efficiency improvement measure, focusing on reducing fuel consumption for one RO-RO car carrier. Utilizing Computational Fluid Dynamics (CFD) software, the methodology incorporates artificial neural networks (ANNs) to develop a mathematical model for estimating key parameters such as the brake power, daily fuel oil consumption (DFOC) and propeller speed. The complex ANN model is then integrated into a user-friendly software tool for practical engineering applications. The research outlines a seven-phase trim optimization process and discusses its potential extension to other types of ships, aiming to establish a universal methodology for CFD-based engineering analyses. Based on the trim optimization results, the biggest DFOC goes up to 10.5% at 7.5 m draft and up to 8% for higher drafts. Generally, in every considered case, it is recommended to sail with the trim towards the bow, meaning that the ship’s longitudinal center of gravity should be adjusted to tilt slightly forward.

Design of an innovative flow isolation device (FID) as an air flow barrier to control the temperature of large storage areas in cold room applications

The virus transmission chain of Covid-19 has a resulted in a significant, global impact on social and working life. Covid-19 vaccines require protective refrigerated conditions during delivery and storage. Warehousing and transportation of these vaccines need to be properly controlled to maintain the product quality and efficacy. Logistics companies developed large-scale refrigerated warehouses as storage relay stations. The heat convection between two rooms of the large-scale, low-temperature warehouses with different temperatures for example (5 °C, -15 °C) should be prevented to improve efficiency. In this study, an innovative flow isolation device (FID) was designed in Taipei Tech to block the storage areas, preventing heat convection. This device can maintain a constant low-temperature in warehouses used for vaccine storage. The axial flow fan draws air from the protected zones (5 °C, -15 °C) into the device. A perforated plate stabilizes the flow rate and maintains a uniform flow direction, creating a flow barrier created between two rooms. This flow can significantly block the heat convection induced by two warehouses with different temperatures. The computational fluid dynamics (CFD) software Ansys Fluent is used to simulate the effect of the FID on the prevention of the heat convection between two rooms. Different case studies were simulated at different machine sizes and supply air flow speeds. The simulated flow patterns and velocity fields are used to evaluate the highest isolation efficiency. The findings show that the FID device can effectively maintain the low temperature of the warehouse. Moreover, the FID helps to avoid heat loss and maintain thermal comfort in working areas, reducing the risk of hypothermia.

Wave dissipation effect of a new combined breakwater and its protective performance for coastal box girder bridges

Breakwaters play an important role in in mitigating wave-induced damage to marine structures. However, conventional submerged breakwaters often exhibit limited wave dissipation capabilities, while floating breakwaters may lack adequate safety performance. Therefore, this study introduces a novel combined breakwater design aimed at addressing the shortcomings of both traditional types. The proposed breakwater integrates a floating structure with a trapezoidal submerged breakwater via an anchor chain connection. To evaluate its efficacy, numerical simulations of wave interactions with structures were conducted using the OpenFOAM computational fluid dynamics (CFD) software in a two-dimensional (2D) numerical flume. Dynamic mesh technology was employed to simulate the motion of the floating body, and the resulting wave loads on a box girder bridge deck positioned behind the breakwater were analyzed to assess the combined breakwater’s protective capabilities and influencing factors. Analysis of wave heights and loads on the bridge deck revealed that the combined breakwater outperformed traditional submerged breakwaters in terms of wave dissipation. Furthermore, it was observed that the protective efficacy of the combined breakwater was more sensitive to variations in the size of the floating body compared to the submerged structure, and more responsive to changes in wave period than wave height. Leveraging the ability of the floating body to attenuate waves near the surface and the enhanced impact resistance provided by the combined floating and submerged structures, the proposed breakwater offers a promising approach to improving wave attenuation performance and enhancing safety for coastal infrastructure.

Effect of installation factors on the environment uniformity of multifunctional fan-coil unit system in Chinese solar greenhouse

Airflow significantly affects crop growth, and providing adequate and uniform airflow is essential to improve crop yield and quality. This paper used computational fluid dynamics software to optimize multifunctional fan-coil unit (FCU) installation factors at different crop heights. Fan pressure jump coefficient got optimized further, and the percentage of disturbance velocity was proposed as an index to evaluate the improvement of turbulence characteristics in airflow fields. The simulation results showed that the FCU system's optimal tilt angle, swing angle, and height above the ground were 20°, 45°, and 2.9 m, respectively. The optimum spacing is related to crop height. For lower tomatoes, the optimal spacing was 4.2 m and 4.5 m for higher tomatoes. The velocity coefficients of variation (Cv-v) for different height crops before optimization were 0.58 and 0.66. The Cv-v after optimization decreased to 0.37 and 0.41, and the uniformity was improved by 36.21 % and 37.88 %; the porous medium amounts percentage in the optimum air velocity range were increased to 64.70 % and 23.50 %. Simultaneously, the homogeneous airflow distribution improved the temperature field uniformity by 46.5 % and 23.95 %. This paper can provide theoretical guidance for the design and installation of FCU systems.