• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.207-208
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• 2003

Increasing interest in indoor air quality (IAQ) control has been found because of its serious effect on human health. To evaluate IAQ, thermal comfort in terms of temperature and velocity distributions of indoor air has to be analyzed in detail. Choice of location for installation of air-conditioner in a building will affect the performance of cooling effect and thermal comfort on the occupants, which in turn will affect the indoor air quality (IAQ) of the building. In this paper, we present a discussion on the proper location of the air-conditioner in order to obtain good thermal comfort for occupant of a typical bedroom in Macao. A set of carefully designed numerical experiments is run with the Computational Fluid Dynamics (CFD) software FLOVENT 3.2 [1]. Reynolds averaged Navier-Stokes equations are solved with finite volume technique and turbulence effects upon the mean flow characteristics is modeled with the k - & model. Assumption of steady state environment is made and only convective and conductive heat transfer from the occupant and air-conditioner are being concerned.

• 한국전산유체공학회지
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• 제21권1호
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• pp.72-77
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• 2016

In this study, effects of thurster axis tilting angle on the thruster-hull interaction and propulsion performance in a dynamic positioning system of offshore plant are numerically investigated. Straight and 7-degree tilted downward thruster models as a form of ducted propeller are considered. For numerical simulations, Reynolds averaged Navier-Stokes equations with SST turbulence model are solved by using STAR-CCM+. Results show that thruster-hull interaction is reduced in 7-degree tilted thruster model with lower vortex strength between thruster and hull bottom, although the propulsion performance does not have noticeable difference in a bollard condition.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 추계 학술대회논문집
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• pp.87-90
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• 2004

A numerical analysis was made for the unsteady flow fields of rotor system of a Tilt-Rotor aircraft in cruise mode. The Reynolds-averaged thin-layer Navier-Stokes equations were discretized by Roe's upwind differencing scheme and integrated in time by the LU-SGS algorithm. The computational domain of the rotor system was constructed by six multi-block Chimera grids. Simulated unsteady flow fields of rotating blades were studied in several different view points.

• 한국전산유체공학회지
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• 제15권4호
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• pp.85-91
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• 2010

In this study, aerodynamic analyses based on unsteady computational fluid dynamics (CFD) have been conducted for a 2-bladed vertical-axis wind turbine (VAWT) configuration. Reynolds-averaged Navier-Stokes equations with standard $k-{\varepsilon}$ and SST $k-{\varepsilon}$ turbulence models are solved for unsteady flow problems. The experiment model of 2-bladed VAWT has been designed and tested in this study. Aerodynamic experiment of the present VAWT model are effectively conducted using the vehicle mounted testing system. The comparison result between the experiment and the computational fluid dynamics (CFD) analysis are presented in order to verify the accuracy of CFD modeling with different turbulent models.

• Journal of Advanced Marine Engineering and Technology
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• 제39권5호
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• pp.548-553
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• 2015

The conventional ejector-diffuser system makes use of high pressure primary stream to propel the secondary stream through pure shear action for the purposes of transport or compression of fluid. It has been widely used in many industrial applications such as seawater desalination, solar refrigeration, marine engineering, etc. The present study is performed numerically to study the performance of a two-stage ejector-diffuser system. The detailed flow phenomenon of the ejector-diffuser system has been critically predicted by means of the numerical approach using compressible Reynolds averaged Navier-Stokes (RANS) equations. The axi-symmetric supersonic ejector-diffuser flow has been solved by a fully implicit finite volume scheme with a two-equation k-omega turbulence model. The numerical results are validated with existing experimental data. Detailed flow physics and their contributions on ejector performance are detected to compare both single-stage and two-stage ejectors. The performance improvement on the ejector-diffuser system is discussed in terms of the mass flux ratio and the coefficient of power.

• Journal of Ship and Ocean Technology
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• 제4권1호
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• pp.11-20
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• 2000

Reynolds-averaged Navier-Stokes equations are numerically solved using a secondorder finite difference method for the analysis of turbulent flows around single and tandem hydrofoils advancing under the free surface. The location of the free surface, not known a priori, is computed from the kinematic free surface condition and the computational grid is conformed at each iteration to the free surface deformation. The eddy viscosity model of Baldwin-Lomax is employed for the turbulence closure. The method is validated through the comparision of the numerical results with the experimental data for a single hydrofoil of a Joukowski foil section. A computational study is also carried out to investigate the effect of the submergence depth and the Froude number on the lift and the drag of the hydrofoil. For tandem hydrofoils, computations are performed for several separation distances between the forward and aft foils to see the interference effect. The result shows clearly how the lift and drag change with the separation distance.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.138-143
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• 2005

In this study, the cross-wind stability of the G7 train and TTX running under the high speed was investigated by using 2-dimensional Reynolds Averaged Navier-Stokes equations. It is very important to analysis the aerodynamic characteristic of bluff body located near a ground at the field of the aeronautical, wind engineering, ground vehicle system. To the point of running stability, it is meaningful to analysis the cross-wind effect to the G7 train and TTX developed by domestic technology. The aerodynamic characteristics of the G7 train equipped by bogie-cover is more superior to the case without bogie-cover. Also 2nd model of TTX has stream-shape body has the more good performance than 1st model of TTX.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 춘계 학술대회논문집
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• pp.169-172
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• 2005

A numerical analysis was made In investigate the pressure diminution of a silencer with baffles for high pressure blast flow fields. Reynolds-Averaged Navier-Stokes equations were solved for an axisymmetric computational domain constructed by multi block Chimera grids. A blast flow field was calculated for the silencers that are with one and three baffles. The evolution of high pressure blast flow fields was observed by depicting calculated contours of pressure. It was found that the tested silencer could achieve 97.7 percent pressure diminution.

• 한국전산유체공학회지
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• 제11권1호
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• pp.1-7
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• 2006

Numerical investigation of a centrifugal compressor volute having a modified straight conical duct hill been made. Three-dimensional Reynolds-Averaged Navier-Stokes equations with $k-{\varepsilon}$ turbulence equation are solved To avoid coordinate singularity at the central axis of the duct, multi-block H-type grid is generated on the circular cross-sections of the volute and stretched toward the solid wall boundary. We obtained numerical results with three different mass flow rates at the volute inlet, namely, with the inlet conditions that give small, medium and large mass flow rates at the outlet of the conical duct. Agreement with the experimental results is observed.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.31-40
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• 2011

Unsteady sheet cavitation on a three-dimensional twisted hydrofoil was studied using an unsteady Reynolds-averaged Navier-Stokes equations solver based on a cell-centered finite volume method. As a verification test of the computational method. non-cavitating and cavitating flow over a modified NACA66 foil section was simulated and validated against existing experimental data. The numerical uncertainties of forces and pressure were evaluated for three levels of mesh resolution. The computed pressure on the foil and the cavity shedding behavior were validated by comparing with existing experimental data. The cavity shedding dynamics by re-entrant jets from the end and sides of the cavity were investigated.