• 한국전산유체공학회:학술대회논문집
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• 2000.10a
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• pp.9-14
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• 2000

Computational methods can be classified roughly into two parts: one is the methods based on a potential flow theory, and the other is numerical solvers(CFD) based on Navier-Stockes equation. Methods based on a potential theory are more effective than CFD when the free surface effect is considered. Especially Rankine source method seems to become widespread for simulations of wave making problems. For computations of viscous flow problems, CFD techniques have rapidly been developed and have shown many successful results in the viscous flow calculation. Present paper introduces a computational system 'WAVIS' which includes a pre-processor, potential ant viscous flow solvers and a post-processor. To validate the system, the calculated results for modem commercial hull forms are compared with measurements. It is found that the results from the system are in good agreement with the experimental data, illustrating the accuracy of the numerical methods employed for WAVIS.

• The KSFM Journal of Fluid Machinery
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• v.4 no.1 s.10
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• pp.38-45
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• 2001

A commercial CFD code is used to compute the 3-D viscous flow field within the impeller of a centrifugal pump. Several preliminary numerical calculations are carried out to determine the influence of the parameters such as the grid systems, the numerical schemes, the turbulence models and the shape of the vaneless diffusers at the design flow rate. The results of the preliminary study are used for the calculation of the off-design flow conditions. The circumferentially averaged results such as the radial and tangential velocities, the exit flow angle, the slip factor, the static pressure and the total pressure are compared with the experimental data at the impeller exit to discuss the influence of the prescribed parameters.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.67-70
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• 2012

Many computational fluid dynamic (CFD) simulations have treated the coal kinetics poorly due to large physical domain sizes and high computational complexity, particularly for the recent oxy-coal boilers. Furthermore, some modelers' lack of understanding of the kinetic rate model seems to worsen the simulation accuracy. This study is to suggest the importance of proper use of single-film global kinetic model generally used in CFD code to describe the oxy-fuel combustion of coal char through simple char burnout calculation.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.305-311
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• 2000

A commercial CFD code is used to compute the 3-D viscous flow field within the impeller o( a centrifugal pump. Several preliminary numerical calculations are carried out to determine the influence of the parameters such as the grid systems, the numerical schemes, the turbulence models and the shape of the vaneless diffusers at the design flow rate. The results of the preliminary study are used for the calculation of the off-design flow conditions. The circumferentially averaged results such as the radial and tangential velocities, the exit flow angle, the slip factor, the static pressure and the total pressure are compared with the experimental data at the impeller exit to discuss the influence of the prescribed parameters.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.524-529
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• 2010

In the present study, a CFD program is developed for the Fluid-Structure Interaction(FSI) analysis. The non-staggered, non-orthogonal, and unstructured grid system was also used to handle the complicated geometries in the program. In order to validate the capabilities of the developed CFD program, various models are investigated by using unstructured and nonorthogonal meshes. The predicted results are a good agreement with analytic solution, experimental data and commercial software. And also PISO algorithm is applied for transient flow analysis. The cyclic boundary condition and baffle cell are developed in order to improve the effectiveness of the calculation for complex geometry.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.121-128
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• 2000

Simple design methods were developed to control the coolant flow rates through cylinder head gasket holes. Applying the concept of flow through an obstruction the ratio of intake to exhaust side flow rates could be easily controlled while maintaining the flow rates per cylinder of the original model. Flow distribution in the coolant passage of the original model was calculated by CFD and the flow rates at the gasket holes were modified based on the calculation results. The calculated flow rated of the modified gasket holes were reasonably close to target values. For more accurate control of the flow rate distribution, a design method with iterative CFD calculations was also suggested. The final size of gasket holes for the target flow rates were obtained just after a few optimization iterations. These methods can be very useful for the optimization of heat transfer characteristics in engine cylinder head and block.

• Special Issue of the Society of Naval Architects of Korea
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• 2005.06a
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• pp.51-56
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• 2005

In this paper, a correlation analysis of wake distribution between model test and CFD was described. CFD calculation was performed by 'WAVIS' which is utilized in hullform development. By using the correlation between model test and CFD, we have estimated M/T wake distribution To control M/T and CFD wake distribution effectively. we have developed the program that it is possible to export to TECPLOT and visualize wake distribution.

• Journal of the Korean Solar Energy Society
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• v.32 no.1
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• pp.40-47
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• 2012

According to the advancement of computer and simulation method, it becomes possible to predict indoor climate precisely by using CFD simulation coupled with heat conduction, convection, and radiation. However, predicting the indoor climate is generally conducted by using a simplified CFD coupled simulation method since it takes quite long time to use a general CFD simulation method. In this study, a simplified CFD coupled simulation was conducted in order to find out the effect of natural ventilation by wind-driven in atrium. As a result of calculation, it was clarified that the natural ventilation driven by temperature difference was not enough to remove the accumulated heat of upper zone and the natural ventilation by wind-driven was needed. Finally, it is required to decide the window direction and size based on correct indoor climate prediction method for the effective use of natural ventilation by wind-driven.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.961-967
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• 2019

This research presents an efficient method based on computational fluid dynamics (CFD) for estimating the resistance performance of a ship with a large settlement amount and a dynamic trim. The settlement of the inviscid flow analysis and the results of dynamic trim were used to set a large attitude for the ship prior to performing a viscous flow analysis; a viscous flow analysis was subsequently performed by Dynamic Fluid Body Interaction (DFBI). This method is termed as method I, in which a simple grating system can be used without employing the overset mesh technique by setting many attitudes before interpretation. Thus, method I is advantageous in reducing calculation time and improving calculation accuracy. The viscous flow analysis was performed using a commercial CFD code STAR-CCM+. Compared with the final convergence result, the first viscous flow analysis result of method I exhibited a variation of less than 1 % of resistance. The result was obtained by changing the gratings each time an attitude is changed at each calculation stage, based on the DFBI method provided to STAR-CCM+ using a simple grating system, which is not a superposed grating. This method is termed as method II. Compared with method II of resistance, method I exhibited a dif erence of 0.03-0.6 % for linear velocity. The results of method I were confirmed to be qualitatively and quantitatively appropriate through comparison with several trillion simulations.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.1
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• pp.47-53
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• 2017

A boundary layer integral combined with a 1-D isentropic core flow model has been successfully used to determine heat transfer rate on the surface of a supersonic nozzle. However its accuracy is affected by the core flow condition which is used as a boundary condition for the integral calculation. Because flow behavior near a nozzle throat deviates from 1-D isentropic condition due to 2-D flow turning and interaction between core flow and boundary layer, accuracy of heat transfer calculation decreases at a nozzle throat. Therefore, CFD is adopted to deduce improved core flow condition and increase accuracy of boundary layer integral at nozzle throat in this research. Euler model and SST $k-{\omega}$ model is solved by CFD code and used as a boundary condition for boundary layer integral. Developed code is tested in the supersonic nozzle from the previous research and improvement in accuracy is observed, especially at nozzle throat and diverging section of the nozzle. Error between experimental result and calculation result reduced by 16% when a calculation is made based on the SST $k-{\omega}$ model. Method developed in this research is expected to be used in thermal design of the rocket nozzle.