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유정열(J.Y.Yoo),윤홍열(H.Y.Yoon),이훈구(H.G.Lee) 한국자동차공학회 1992 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The complex geometry of a two-dimensional engine room has been modelled and the thermal and fluid flow therein have been analyzed by using a commercially available code, PATRAN/FLOTRAN. FLOTRAN adopts a finite element method with streamline upwind formulation for convective terms and the k-? turbulence model to solve the three dimensional turbulent flow and heat transfer problems. Velocity vectors, pressure and temperature distributions have been obtained for various cases with different arrangements of license plates, underbody-covers and air dams. The results show that the numerical analysis using PATRAN/FLOTRAN can predict qualitatively well the practical phenomena.<br/>
[論文] 엔진룸 내의 열유체 유동의 2차원 수치시뮬레이션
유정열(J. Y. Yoo),윤홍열(H. Y. Yoon),이훈구(H. G. Lee) 한국자동차공학회 1992 오토저널 Vol.14 No.6
The complex geometry of the engine room of a passenger car has been modelled two-dimensionally and the thermal and fluid flow therein have been analyzed by using a commercially available code, PATRAN/FLOTRAN. FLOTRAN adopts a finite element method with streamline upwind formulation for convective terms and the k-ε turbulence model to solve the three dimensional turbulent flow and heat transfer problems. Velocity vectors, pressure and temperature distributions have been obtained for various cases with different aITII.ngements of license plates. underbody-covers and air dams. The results show that the numerical analysis using PATRAN/FLOTRAN can predict qualitatively well the practical phenomena.
PDMS 채널 내 전단유도에 의한 입자의 운동특성에 관한 연구
김영원(Y. W. Kim),유정열(J. Y. Yoo) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
An experimental study has been conducted to quantitatively characterize particle motion under shear-induced migration in square-PDMS microchannels by applying μ-PTV technique, and to compare with previous results carried out in macro-scale flow through a tube. It is shown that as the Reynolds number (Re) is increased, neutrally buoyant particles drift away from the wall and away from the center of the channel due to inertial migration. Particles are accumulated at the equilibrium position of 0.67H, with H being a half width of the channel, which is analogous to that of tube flow. Equilibrium position is nearly independent of Re and the maximum value of particle probability density function (PDF) is linearly increased as Re is increased. The outermost edge of particle cluster is in good agreement with previous results, and it is rapidly converged to about 0.7 at L₃ (reduced tube length proposed by Segre & Silberberg) = 1. Our study quantitatively presents an understanding of shear-induced particle migration in square microchannels and is associated with the study performed in macro scale. Furthermore, the present study gives optimum factors for designing of microfluidic systems.
류종우(J.Ryu),조성권(S.K.Cho),양준모(J.M.Yang),유정열(J.Y.Yoo),최해천(H.Choi),이준식(J.S.Lee) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.6_2
Numerical and experimental studies are performed to investigate the effect of the underbody shape of the simplified road vehicle on drag and lift. Four different vehicle models with front and rear slanted variations at the lower surface are used in this study. Cases with a slanted underbody surface at front have smaller drag than those without a slanted surface. Also, cases with a slanted underbody surface at rear have smaller lift than those without a slanted surface. Pressure distributions along the model surfaces and velocity fields at the wake region are examined in detail. In general, numerical solutions are in agreement with experimental results.<br/>
장성원(S. W. Chang),유정열(J. Y. Yoo),이택식(T. S. Lee) 한국자동차공학회 1990 오토저널 Vol.12 No.3
A wind tunnel experiment for the flow around a 1/5 scale passenger vehicle model has been carried out. A 5-hole Pitot tube is used for measuring velocity distributions around the model and a scanivalve with 48 ports is used for measuring surface pressure distribution at various Reynolds numbers. In order to observe the flow on the surface and in the wake region, a flow visualization experiment has been perfonned using wool tuft with and without paper cones. In addition, a 2-dimensional viscous calculation considering only the mid-plane section of the model has been performed.<br/> A complex wake structure in the immediate rear of the model has been confirmed. The distributions of the surface pressure coefficient are not sensitively dependent on the Reynolds Number. In the first half of the model, they do not seem to vary from section to section. However, in the second half, they do vary from section to section, especially at the bottom surface, which indicates that the cross flow vortex is more affected by the bottom surface than the top surface. The qualitative agreement of the measured and calculated velocity field also explains the usefulness of the 2-dimensional calculation in the limited sense.
양희천(H.C.Yang),유정열(J.Y.Yoo),이준식(J.S.Lee),최해천(H.Choi) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.11_1
In this paper three-dimensional external airflow around road vehicle models was numerically studied to investigate the aerodynamic characteristics. FVM based on a general curvilinear coordinate system was used to solve the governing equations. The drag coefficients by the calculation were about 40-50% higher than the experimental values.<br/>