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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.