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난류박리 및 재부착 유동에 대한 저레이놀즈수 비선형 열전달 모형의 개발
리광훈,성형진,Rhee, Gwang-Hoon,Sung, Hyung-Jin 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.2
A nonlinear low-Reynolds-number heat transfer model is developed to predict turbulent flow and heat transfer in separated and reattaching flows. The $k-{\varepsilon}-f_{\mu}$ model of Park and Sung (1997) is extended to a nonlinear formulation, based on the nonlinear model of Gatski and Speziale (1993). The limiting near-wall behavior is resolved by solving the $f_{\mu}$ elliptic relaxation equation. An improved explicit algebraic heat transfer model is proposed, which is achieved by applying a matrix inversion. The scalar heat fluxes are not aligned with the mean temperature gradients in separated and reattaching flows; a full diffusivity tensor model is required. The near-wall asymptotic behavior is incorporated into the $f_{\lambda}$ function in conjunction with the $f_{\mu}$ elliptic relaxation equation. Predictions of the present model are cross-checked with existing measurements and DNS data. The model preformance is shown to be satisfactory.
리광훈,성형진,Rhee, Gwang-Hoon,Sung, Hyung-Jin 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.3
An unsteady numerical simulation was performed for locally-forced separated and reattaching flow over a backward-facing step. The local forcing was given to the separated and reattaching flow by means of a sinusoidally oscillating jet from a separation line. A version of the $k-{\varepsilon}-f_{\mu}$ model was employed, in which the near-wall behavior without reference to distance and the nonequilibrium effect in the recirculation region were incorporated. The Reynolds number based on the step height (H) was fixed at $Re_H=33000$, and the forcing frequency was varied in the range $0{\leq}St_H{\leq}2$. The predicted results were compared and validated with the experimental data of Chun and Sung. It was shown that the unsteady locally-forced separated and reattaching flows are predicted reasonably well with the $k-{\varepsilon}-f_{\mu}$ model. To characterize the large-scale vortex evolution due to the local forcing, numerical flow visualizations were carried out.
리신호,리광훈,Rhee, Shin-Ho,Rhee, Gwang-Hoon 한국농공학회 2007 한국농공학회논문집 Vol.49 No.1
The heat flow characteristics of the Gudle (traditional Ondol) used a lot at farm houses have been performed with variations of Bunengki (Fireridge) by numerical analysis and field experiment. The Doedon-Gorae (Return-Firetunnel) Gudle is analyzed among the structure of Gudle. The distribution of heat flow in Gorse (Firetunnel) and the temperature distribution in floor of 3 Buneomgi (Fire ridge) was more uniform than that of 1 Buneomgi. The heat efficiency of 3 Buneomgi was higher than that of 1 Bunengki. That is, the 3 Bunengk is more efficient and more uniform temperature.
마이크로 유로에서 맥동유동에 의한 혼합촉진에 관한 수치해석
김서영(Seo Young Kim),리광훈(Gwang Hoon Rhee) 한국유체기계학회 2003 유체기계 연구개발 발표회 논문집 Vol.- No.-
A numerical study has been conducted to investigate the effect of an inlet flow pulsation on mixing of two solutions with different concentrations in a micro conduit. We treat an unsteady, incompressible and two-dimensional flow through a micro conduit by adopting the momentum equations with the electrostatic force due to streaming current and the concentration equation. The feasibility of the inlet flow pulsation to enhance the mixing process inside the micro conduit is carefully examined by varying the inlet pulsation frequency. When a low-frequency pulsation is induced at the inlet, the interface between two solutions with different concentrations becomes wavy, which results in mixing enhancement. As the pulsation frequency increases, the waviness of the interface becomes meager, and the concentration gradients at the interface approach the value for the non-pulsating steady flow.