Computational Fluid Dynamics Simulation Model Research Articles

Development of a VR simulator for educating CFD-computed internal environment of piglet house

In terms of maintaining an optimum micro-climates in livestock facilities, many problems exist. In particular, many consultants, as well as farmers, have misunderstand the process and often made wrong judgements on ventilation. Airflow is the main mechanism of internal environmental distribution. However, airflow is invisible and difficult to predict and measure. Computational fluid dynamics (CFD) simulations have been used to analyse the aerodynamics of livestock building micro-climates. CFD-computed results can be used to educate farmers and consultants. However, they can be of limited use when providing education via a two-dimensional screen. This could be improved by visualising the computed results in a three-dimensional space rather than on a two-dimensional surface. This could be accomplished using virtual reality (VR). In this study, CFD-computed results were combined with VR technology to develop an educational simulator. Firstly, an extensive review was carried out of research papers, reports, journals, and publications on the livestock industry, to find seasonally representative problems that occurred at piglet rearing houses in Korea. Then, a CFD simulation model was designed for computing the micro-climate of a piglet house according to its external climate and ventilation type. These CFD models were designed based on a 2009 Korean standard for piglet houses using validation results of a previous study (Kim et al., 2017). The CFD-computed results, such as internal airflow, air temperature, humidity, and gas, were then applied to a VR simulator for educating farmers and consultants. Finally, a user interface was developed to maximise accessibility and usability for VR users.

Analysis of the Spatial and Temporal Variations of Land Surface Temperature Based on Local Climate Zones: A Case Study in Nanjing, China

The concept of local climate zone (LCZ) has standardized the calculation of urban heat island (UHI) intensity (UHII) and established the connection among urban morphology, surface property, and UHI. In addition, LCZ has provided a new insight into the studies on urban thermal environment. This study selected Nanjing, China, as the study area and utilized a combined method that comprised remote sensing based and geographic information system based methods based on random forest classifier for LCZ classification. Overall accuracy reached 92%, and kappa coefficient was 0.911. In addition, the seasonal and diurnal differences of land surface temperature (LST) were analyzed via LST retrieval from Landsat data and computational fluid dynamics model simulation, respectively. Results confirmed the warmest and coldest zones in four seasons. The LST distribution characteristics of land cover and built types were basically the same during the four seasons. Moreover, the UHII difference of an LCZ class in various seasons and the UHII difference of a season in various LCZs were investigated. The daily LSTs of the simulated LCZs (1 to 6) within 24 h showed the same variation law but different variation extents in a day. The LST variations of built types were related to building elements, such as building height, building density, building layout, and green ratio. This study identified an existing relation between LST and LCZ and analyzed LST on the basis of LCZs from seasonal and diurnal scales, which provides guidance for future researchers.

Detailed study of key boundary parameters influence on a turbocharged diesel engine based on thermodynamic analysis

In present study, the test platform and computational fluid dynamics simulation model of a turbocharged diesel engine are employed to explore energy balance, exergy balance, exergy terms variation, exergy destruction formation causes and spatial distribution in wider adjustment ranges of intake air temperature, coolant temperature and exhaust gas recirculation rate at different working conditions in detail. The results indicate that first, adjusting intake air temperature from 30 °C to 70 °C, exergy efficiency, exergy destruction and exhaust energy are negatively correlated with intake air temperature, while the change trends of exhaust exergy and heat transfer terms are opposite. Secondly, enhancing coolant temperature from 50 °C to 90 °C, heat transfer terms decreases significantly and effective work increases, while exhaust terms and exergy destruction remain basically unchanged. Third, exhaust gas recirculation rate increases from 5% to 30%, heat transfer exergy decreases, while effective work increases first and then decreases, in-cylinder exergy destruction decreases first and then increases. Fourth, there are several characteristics of in-cylinder exergy destruction at different key boundary parameters: (a) exergy destruction chiefly occurs in combustion process, (b) high exergy destruction rate primarily focuses in richer mixture region, (c) exergy destruction rate is negatively correlated with in-cylinder local temperature in the same heat release rate region. Finally, root reasons for the influences of key boundary parameters on exergy destruction are in-cylinder local equivalent ratio and temperature. Adjusting of intake air temperature, coolant temperature and exhaust gas recirculation rate reasonably to enhance temperature and promote diluted mixing of oil-air appropriately can effectively suppress exergy destruction and optimize efficiency.

Thermal analysis of oil sump and compression unit in a rotary compressor

Thermal analysis of the oil sump and compression unit in a hermetic rotary compressor is important for enhancing its performance and reliability. In this study, the temperature distribution, heat-transfer mechanism, and heat balance of the oil sump and compression unit in a rotary compressor were analyzed using the 3D computational fluid dynamics (CFD) fluid-solid coupled model. Considering the practical characteristics of the rotary compressor, some special treatments are proposed for the simulation model. Instead of using empirical formulations, heat-transfer coefficients in the upside of the main bearing and compressor shell were obtained using the 3D CFD simulation model; the dynamic process in the suction chamber and compression chamber was considered to be static and the oil film in the inner wall of the cylinder, rib effect of the A-frame structure at the bottom of the compressor shell, and friction loss in the side of the sliding vane were considered. The simulation results showed good agreement with experimental results. We expect that these analytical results would be of great use in further understanding the temperature distribution and heat-transfer mechanism of oil sumps and compression units and also provide guidelines for improving the performance and reliability of rotary compressors.

Scaling spray combustion processes in marine low-speed diesel engines

Scaled model experiments would be very effective in reducing cost, time and energy consumption in marine diesel engine development, however, relevant researches are rarely reported. The aim of this paper is to explore the potential of scaled model experiments for marine low-speed diesel engines, and provide references for researchers who attempt to conduct scaled model experiments in marine diesel engine development. At first, the computational fluid dynamics simulation model is established and calibrated against the experimental data from a marine low-speed diesel engine with 340 mm bore diameter. Then, three scaling laws for spray mixture formation and combustion processes as well as pollutant emissions are numerically studied with the baseline 340 mm-bore engine and an up-scaled 520 mm-bore engine at various injection timings. The results reveal that the spray mixture formation processes, in-cylinder temperature and pressure traces, and indicated thermal efficiency can be well scaled between the 340 and 520 mm-bore engines, while the three scaling laws show different degrees of similarity in soot and nitrogen oxides emissions. The increased heat transfer losses of the small engine are identified as a major obstacle to achieve the overall similarity, and the wall temperature setting methods to scale the heat transfer loss are theoretically derived and numerically verified. With the sophisticated control of the cylinder wall temperatures of the small engine, the discrepancy in soot and nitrogen oxides emissions between the large and small engines is reduced.

An Integrated Hydrological-CFD Model for Estimating Bacterial Levels in Stormwater Ponds

A hydrological model was integrated with a computational fluid dynamics (CFD) model to determine bacteria levels distributed throughout the Inverness stormwater pond in Calgary, Alberta. The Soil Conservation Service (SCS) curve number model was used as the basis of the hydrological model to generate flow rates from the watershed draining into the pond. These flow rates were then used as input for the CFD model simulations that solved the Reynolds-Averaged Navier-Stokes (RANS) equations with k-ɛ turbulence model. E. coli, the most commonly used fecal indicator bacteria for water quality research, was represented in the model by passive scalars with different decay rates for free bacteria and attached bacteria. Results show good agreement with measured data in each stage of the simulations. The middle of the west wing of the pond was found to be the best spot for extracting water for reuse because it had the lowest level of bacteria both during and after storm events. In addition, only one of the four sediment forebays was found efficient in trapping bacteria.

Numerical study on a water cooling system for prismatic LiFePO4 batteries at abused operating conditions

Cooling of the Li-ion battery module is a critical issue for electric vehicles in regard with the battery performance and lifetime, particularly at abused operating conditions. A water cooling system consisting of two novel cover plates with T-shape bifurcation structures and eight traditional cold plates was proposed and investigated for cooling of prismatic LiFePO4 battery modules. A computational fluid dynamics simulation model of the cooling system was established and validated by experimental data. The results show that a cold plate with four circular mini-channels flowing water can keep the maximum temperature of a single battery around 35 °C at 1 °C discharging rate and ambient temperature of 40 °C. Effect of the coolant flow rate is much less significant than the inlet coolant temperature on the cooling performance. Two sets of the proposed water cooling systems can significantly reduce the maximum temperature of a battery module consisting of 15 batteries. Moreover, great temperature distribution uniformity between different batteries can be achieved because the novel cover plate is able to distribute water evenly into each mini-channel of the cold plates. The cooling system can keep the maximum temperature of the module below 32.5 °C and the difference between the highest and lowest temperatures around 1.5 °C at abused operating conditions.

Effect of Interfacial Tension on Internal Waves Based on Boussinesq Equations in Two-Layer Fluids

Mohapatra, S.C.; Gadelho, J.F.M., and Guedes Soares, C., 2019. Effect of interfacial tension on internal waves based on Boussinesq equations in two-layer fluids. Journal of Coastal Research, 35(2), 445–462. Coconut Creek (Florida), ISSN 0749-0208.An analytical model associated with internal waves in the presence of interfacial tension bounded by a rigid floating plate and rigid bottom in a two-layer fluid is presented based on Boussinesq equations. The general governing equations and boundary conditions of internal wave motion under interfacial tension are described. The detail of the Boussinesq equations associated with interfacial tension with two depth parameters that indicate the specific elevations in upper-and lower-layer fluids are obtained based on an expansion of velocity potentials as a power series in the dispersive effect. For simplicity, the one-dimensional linearized Boussinesq equations and dispersion relation with interfacial tension are obtained. The first- and second-order internal wave amplitudes with interfacial tension based on a perturbation technique are derived, and the super- and subharmonic interactions of second-order internal waves are obtained. The accuracy of the analytical result of internal wave displacement is verified by comparing it with computational fluid dynamics model simulations without introducing interfacial tension, and it is observed that the wave profiles and their peak amplitudes agree well. Furthermore, the linearized dispersion relation is compared with one recently obtained. The influences of interfacial tension on internal wave properties are studied by analyzing dispersion relation, fluid particle velocities, first- and second-order harmonic waves on super- and subharmonic transfer functions, and shoaling gradients. It is found that smaller values of interfacial tension and wavenumber ratio result in stronger second-order effect on the internal wave profile. Finally, an application of interfacial tension is demonstrated in the presence of surfactants for partitioning oil–water interface.

Study on the Cooling Effect of Attached Fins on PV Using CFD Simulation

The issue of efficiency decrease according to temperature increase is a pending problem in the PV market. Several active and passive technologies have been suggested but few quantitative studies on the estimation of the cooling effect have been carried out. In this study, a CFD (computational fluid dynamics) simulation model was developed to analyze a passive cooling technology using fins attached to the back of the PV module. Furthermore, a method to improve airflow at the back of the PV module by forming slits in the frame was analyzed. The simulation model reproduced the indoor test that uses a solar simulator and the cooling performance was analyzed according to the shape of the fins and the presence of slits. In the simulation results, the surface temperature and expected electrical efficiency without cooling were 62.78 °C and 13.24% respectively under nominal operating cell temperature conditions. Moreover, the temperature reduced by approximately 15.13 °C because the fins attached at the bottom of the PV module increased the heat transfer area with airflow. Thus, the electrical efficiency according to the PV module temperature was predicted as 14.39%. Furthermore, when slits were installed between the fins, they increased the airflow velocity and accelerated the formation of turbulence, thereby improving the cooling performance of the fins. The simulation results showed that the temperature could be further reduced by approximately 8.62 °C at a lower air velocity. As the fins and slits can also reduce the non-uniformity of the temperature, they are expected to supplement the efficiency and durability reduction of the PV modules caused by the hot spot phenomenon. In addition, it was shown that slits in the frame could further improve the cooling performance of the fins at a low-velocity airflow.

Numerical simulation of dispersion and distribution behaviors of hydrogen leakage in the garage with a crossbeam

A three-dimensional computational fluid dynamics simulation model resolved by the unsteady Reynolds-Averaged Navier–Stokes equations was developed to predict hydrogen dispersion in an indoor environment. The effect of the height of the crossbeam (Hc) on hydrogen dispersion and distribution behaviors in a four-car garage was numerically investigated under fully confined and natural ventilation conditions. For the fully confined condition, the garage was almost completely filled with a flammable hydrogen cloud at t=600 s. In addition, the volumetric ratio of the flammable region, thickness of the hydrogen stratification, and hydrogen mole fraction all increased as Hc increased. When two symmetric ventilation openings were set up, the volumetric ratio of the flammable region decreased by 50% at t=600 s. Moreover, Hc had evident influence on the vertical distribution of hydrogen mole fraction. In addition, there existed little explosion hazard under the height of 1.6 m. The results show that Hc was a non-negligible factor for the safety design of hydrogen in the garage and Hc=0.12 m was the optimal height of the crossbeam. Furthermore, the ventilation system in the present study cannot completely eliminate the risk of hydrogen explosion. The present risk assessment results can be useful to analyze safety issues in automotive applications of hydrogen.

An improved SST [formula omitted] model for pollutant dispersion simulations within an isothermal boundary layer

The selection of turbulence models has always been one of the important aspects of computational fluid dynamics model simulations of wind flow and pollutant dispersion problems. The commonly industrially adopted steady Reynolds-averaged Navier–Stokes turbulence models are the realizable k−ε model and Menter's shear stress transport k−ω model.In this study, we demonstrated that the realizable k−ε model and Menter's SST k−ω model produced non-satisfactory correlation results with the experimental data, in terms of the normalized pollutant concentration for a cuboid obstacle.Here, an improved formulation of Menter's SST k−ω turbulence model, particularly for the wind flow and pollutant dispersion simulations, is applied. The modifications have been added in a systematic manner which include the addition of damping functions in the closure equations, the inclusion of the turbulent cross-diffusion term in the omega equation, and the re-establishment of model constants and parameter profiles. Considerable improvement in the correlation between the prediction and the experimental data up to a value of 0.78 with matching wind and turbulent kinetic energy profiles was obtained by the proposed model. Significant reduction of more than 80% in NSME and a satisfactory FAC2 value of 0.54 are also achieved with the improved model.

CFD model simulation of bubble surface area flux in flotation column reactor in presence of minerals

Bubble surface area flux (Sb) is one of the main design parameter in flotation column that typically employed to describe the gas dispersion properties, and it has a strong correlation with the flotation rate constant. There is a limited information available in the literature regarding the effect of particle type, density, wettability and concentration on Sb. In this paper, computational fluid dynamics (CFD) simulations are performed to study the gas–liquid–solid three-phase flow dynamics in flotation column by employing the Eulerian–Eulerian formulation with k-ε turbulence model. The model is developed by writing Fortran subroutine and incorporating then into the commercial CFD code AVL FIRE, v.2014. This paper studies the effects of superficial gas velocities and particle type, density, wettability and concentration on Sb and bubble concentration in the flotation column. The model has been validated against published experimental data. It was found that the CFD model was able to predict, where the response variable as indicated by R-Square value of 0.98. These results suggest that the developed CFD model is reasonable to describe the flotation column reactor. From the CFD results, it is also found that Sb decreased with increasing solid concentration and hydrophobicity, but increased with increasing superficial gas velocity. For example, approximately 28% reduction in the surface area flux is observed when coal concentration is increased from 0 to 10%, by volume. While for the same solid concentration and gas flow rate, the bubble surface area flux is approximately increased by 7% in the presences of sphalerite. A possible explanation for this might be that increasing solid concentration and hydrophobicity promotes the bubble coalescence rate leading to the increase in bubble size. Also, it was found that the bubble concentration would decrease with addition of hydrophobic particle (i.e., coal). For instance, under the same operating conditions, approximately 23% reduction in the bubble concentration is predicted when the system was working with hydrophobic particles. The results presented are useful for understanding flow dynamics of three-phase system and provide a basis for further development of CFD model for flotation column.

Heat Transfer Enhancement of the Air-Cooling Tower with Rotating Wind Deflectors under Crosswind Conditions

To investigate the effect of wind deflectors on air flow and heat transfer performance of an air-cooling tower under crosswind conditions, an experimental system based on a surface condenser aluminum exchanger-type indirect air-cooling tower is established at a 1:100 proportional reduction. A 3-D computational fluid dynamics simulation model is built to study the air flow and temperature fields. The air flow rate into the cooling tower and the heat transfer rate of the radiators are used to evaluate cooling performance. Rotating wind deflectors are adopted to reduce the influence of crosswind on the cooling tower performance. The effects of the rotating wind deflectors on the thermal-hydraulic characteristics of the air-cooling tower under different environmental crosswind speeds are studied. Results indicate that the wind direction in the tower reverses as the rotating speed of the wind deflectors increases. The thermal performance of an air-cooling tower under crosswind conditions can be improved by using rotating wind deflectors. The heat transfer rate of a cooling tower with eight wind deflectors begins to increase when the rotating speed exceeds 2 r/min.

Adaptive response prediction for aerodynamic shape optimization

PurposeThe purpose of this paper is to reduce the overall computational time of aerodynamic shape optimization that involves accurate high-fidelity simulation models.Design/methodology/approachThe proposed approach is based on the surrogate-based optimization paradigm. In particular, multi-fidelity surrogate models are used in the optimization process in place of the computationally expensive high-fidelity model. The multi-fidelity surrogate is constructed using physics-based low-fidelity models and a proper correction. This work introduces a novel correction methodology – referred to as the adaptive response prediction (ARP). The ARP technique corrects the low-fidelity model response, represented by the airfoil pressure distribution, through suitable horizontal and vertical adjustments.FindingsNumerical investigations show the feasibility of solving real-world problems involving optimization of transonic airfoil shapes and accurate computational fluid dynamics simulation models of such surfaces. The results show that the proposed approach outperforms traditional surrogate-based approaches.Originality/valueThe proposed aerodynamic design optimization algorithm is novel and holistic. In particular, the ARP correction technique is original. The algorithm is useful for fast design of aerodynamic surfaces using high-fidelity simulation data in moderately sized search spaces, which is challenging using conventional methods because of excessive computational costs.

Effect of Gas Velocity Distribution on Heat Recovery Process in Packed Bed of Plate-Shaped Slag

A new twin-roll continuous slag solidification process and heat recovery process from a slag packed bed was developed for utilization of the waste heat of steelmaking slag. Plate-shaped slag with the thickness about 7 mm was successfully produced in a pilot plant, and the sensible heat of the slag was recovered by blowing air into the slag chamber. However, the gas distribution inside the slag packed bed was unclear because of the unique shape of the slag plates, and this remained a concern for further scale-up designing of the slag chamber. Therefore, in order to estimate the gas distribution in the packed bed, a simple computational fluid dynamics (CFD) model which considers the wall effect around the inner wall of the chamber was developed, and this model was fitted to the results of laboratory-scale velocity distribution measurements. The results showed that the gas velocity distribution was properly estimated, and the intensity of the wall effect was similar in both cases. As the next step, the gas velocity distribution and its effect on the slag heat recovery process in a pilot-scale slag chamber were evaluated with the assistance of the CFD simulation model. The simulation results were compared with the measured data obtained in a pilot-scale test, and as the result, a similar wall effect was also observed in the pilot-scale chamber. However, the intensity of the wall effect was limited enough to prevent serious deterioration of the uniformity of the gas distribution.

A numerical and experimental investigation on the performance of a low-flux direct absorption solar collector (DASC) using graphite, magnetite and silver nanofluids

Application of nanofluids as a potential working fluid in solar-to-thermal energy conversion systems has shown remarkable improvements in solar power systems. Herein, a combined numerical and experimental study has been conducted on a nanofluid direct absorption collector utilizing three types of nanoparticles (i.e., graphite, magnetite, and silver) dispersed in deionized water as the absorbing medium. To increase the dispersion stability, surface modification was performed on the nanoparticles prior to the preparation of nanofluids via the two-step method and the optical characteristics of nanofluids were experimentally evaluated prior to their use in the DASC. A two-dimensional computational fluid dynamics simulation model was developed to solve the radiative transfer in particulate media and heat transfer equations. Considering the absorption and scattering within the nanofluid medium, the nanofluid temperature distribution within the collector was evaluated. Simultaneously, experiments were performed on a direct absorption collector to validate the numerical model and to investigate the effect of solar flux intensity, nanoparticle concentration and flow rate on the collector thermal performance. According to the results, nanofluids promoted the thermal and exergy efficiencies by 33–57% and 13–20%, respectively than the base fluid.

Earth-Air Heat Exchanger thermal performance in Egyptian conditions: Experimental results, mathematical model, and Computational Fluid Dynamics simulation

In this paper, the thermal performance of an Earth-Air Heat Exchanger (EAHE) used for heating and cooling purposes is investigated under Egyptian weather conditions. The soil temperature profile and the temperature distribution of flowing air through horizontal Earth-Air Heat Exchanger (EAHE) is experimentally studied. Also, a mathematical model based on unsteady, one-dimensional and quasi-state is developed for energy conservation equation. Moreover, an explicit finite difference numerical method is used to solve the developed mathematical model with the help of MATLAB code. Finally, three-dimensional, steady and double precision Computational Fluid Dynamics (CFD) ANSYS Fluent simulation model is established to predict the air and soil temperature. Whereas, the standard κ-∈ model is applied to simulate the turbulence kinetic energy of the flowing fluid. The mathematically developed model and CFD simulation result validated against experimental results. Good agreement is achieved with an average error and correlation coefficient of 2.09, 97% and 3.3 and 95.5% for CFD simulation and mathematical model respectively. The CFD model is used in a parametric investigation. A parametric study carried out to explore the impact of different parameters such as pipe diameter, pipe material, pipe space, pipe length and flowing fluid velocity. The results show that some of these parameters have noticeable results in air temperature. Whereas, the pipe diameter increases the air temperature decreases. The outlet air temperature declines from 20.4°C to 18.7°C as the pipe diameter expands from 2 to 3in. Furthermore, as pipe length increases, outlet air temperature enhances. The temperature changes from 19.7 to 19.9°C as the pipe length elongates from 5.45m to 7m. A bit change occurs in outlet air temperature from 19.7°C to 19.8°C when pipe space changes from 0.2 to 0.5m. Moreover, three different pipe materials such as PVC, steel and copper are implied. The outlet air temperature was 19.7°C in PVC pipe and 19.8, 19.8°C for steel and copper respectively. So the conclusion is that the change in outlet air temperature for various pipe material is neglected compared with their prices. Finally, the effect of fluid velocity was investigated. Therefore, the outlet air temperature declines from 20.4°C to 19.2°C as air accelerates from 1 to 3m/s.

A simplified assessment of how tree allocation, wind environment, and shading affect human comfort

Urban areas encounter a common problem called the heat island effect. Public-space plantings and parks have become a crucial countermeasure for decreasing urban temperatures. In this study, field measurements were carried out in a subtropical park in the summer to investigate the effect of plantings on microclimate and the thermal environment of pedestrian areas. It was found that obstructions affected the wind field; although cold air enters parks, an overcrowding of plants resulted in temperature rises in downstream areas. Shading is a key to thermal comfort in both tropical and subtropical regions, and its effect is augmented by ventilation. Trees that are planted without proper planning can decrease wind movement, which in turn has a detrimental effect on thermal comfort, especially downwind. Wind corridors through urban parks can promote both shading and ventilation, improving thermal comfort, and should thus be considered when designing the layout and trimming of plantings. Data from both fixed- and mobile-type measurements were used to validate the feasibility of a computational fluid dynamics simulation model. It was observed that wind speed and shading are the two main variables that influence the human comfort index, based on which a simpler human comfort assessment was proposed to replace the conventional index, standard effective temperature (SET*). The proposed method can be used as a guideline for landscape architects when designing planting locations.

Eulerian–Lagrangian modeling and computational fluid dynamics simulation of wire mesh demisters in MSF plants

This study focuses on computational fluid dynamics model (CFD) for simulation of demisters in multistage flash desalination (MSF). The Eulerian–Lagrangian model (steady-state and two-dimensional) was developed to simulate the demister. The model was used to simulate the flow of water vapor and brine droplets in the demister. The computational domain includes the following three zones: the vapor space above the demister, the vapor space below the demister, and the demister. The demister zone was modeled as tube banks. A sensitivity analysis of the model revealed that vapor velocity is the main parameter that affects demister performance. Additionally, the analysis indicated that vapor temperature had no effect on the pressure drop across the demister. The developed model was validated using data from both the literature and real MSF plants. Analysis indicated that model predictions and experimental data were consistent. This work gives extensive details for CFD modeling of the MSF demister. The work is based on a previous study by Al-Fulaij et al. (2014). This work is part of a group effort to develop a comprehensive CFD simulation for the entire flashing stage of the MSF process, which would provide an extremely efficient and inexpensive design and simulation tool to the desalination community.

전산유체역학을 통한 간척지 내 벤로형 온실의 자연환기량 분석

Recently, the Korean government announced a new development plan for a large-scale greenhouse complex in reclaimed lands. Wind environments of reclaimed land are entirely different from those of inland. Many standard books for ventilation design didn't include qualitative standard for natural ventilation. In this study, natural ventilation rates were analyzed to suggest standard for ventilation design of venlo type greenhouse built on reclaimed land. CFD (Computational Fluid Dynamics) simulation models were designed according to the number of spans, wind conditions and vent openings. The wind profile at a reclaimed land was designed using ESDU (Engineering Sciences Data Unit) code. Using the designed CFD simulation model, ventilation rates were computed using mass flow rate and tracer gas decay method. Additionally computed natural ventilation rates were evaluated by comparing with ventilation requirements. As a result of this study, ventilation rates were decreased with increasing of the number of spans. Ventilation rates were linearly increased with increasing of wind speed. When the wind speed was , only side vent was open and wind direction was , homogeneity of ventilation rate at 0~1 m height is the worst. Finally, chart for computing natural ventilation rate was suggested. The chart was expected to be used for establishing standard of ventilation design.