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RISS 인기검색어
- 검색키워드
- 저자 : 백성구(Seong Gu Baek) (검색결과 5 건)
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Explicit Algebraic Stress/Heat-Flux 모형을 이용한 벽면가열이 높은 수직관 내의 열전달 감소에 대한 수치적 해석
백성구,박승오,Baek, Seong-Gu,Park, Seung-O 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.12
This paper assesses the prediction performance of explicit algebraic stress and heat-flux models for reduction of heat transfer coefficient in a strongly-heated vertical tube. Two explicit algebraic stress models and four explicit algebraic heat-flux models are selected for assessment. Eight combinations of explicit algebraic stress and heat-flux models are used in predicting the turbulent gas flows with intense heating, which yields the significant property-variation. The results showed that the two combinations of GS-AKN and WJ-mAKN predicted the Nusselt number and the axial wall temperature variations well and that the predictions of Nusselt number with WJ-combinations spread in a wider range than those with Gs-combinations. WJ is the explicit algebraic stress model of Wallin and Johansson and GS is the model of Gatski and Speziale and that AKN is the explicit heat-flux model of Abe, Kondoh and Nagano and mAKN is the modified AKN.
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압력구배가 변하는 표면 위의 Bypass 천이 유동의 예측
백성구,정명균,임효재,Baek-Seong-Gu,Chung, Myung-Kyoon,Lim, Hyo-Jae 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.6
A modified $textsc{k}$-$\varepsilon$model is proposed for calculation of transitional boundary-layer flows with changing pressure gradient. In order to develop the model for this problem, the flow is divided into three regions; pre-transition region, transition region and fully turbulent region. The effect of pressure gradient is taken into account in stream-wise intermittency factor, which bridges the eddy-viscosity models in the pre-transition region and the fully turbulent region. From intermittency data in various flows, Narashima's intermittency function, F(${\gamma}$), has been found to be proportional to $\chi$$^{n}$ according to the extent of pressure gradient. Three empirical correlations of intermittency factor being analyzed, the best one was chosen to calculate three benchmark cases of bypass transition flows with different free-stream turbulence intensity under arbitrary pressure gradient. It was found that the variations of skin friction and shape factor as well as the profiles of mean velocity in the transition region were very satisfactorily predicted.
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압력 구배가 없는 평판 천이 경계층 유동을 예측하기 위한 k-$\varepsilon$모형의 개발
백성구,임효재,정명균,Baek, Seong-Gu,Im, Hyo-Jae,Jeong, Myeong-Gyun 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.3
A modified model is proposed for calculation of transitional boundary layer flows. In order to develop the eddy viscosity model for the problem, the flow is divided into three regions; namely, pre-transition region, transition region and fully turbulent region. The pre-transition eddy-viscosity is formulated by extending the mixing length concept. In the transition region, the eddy-viscosity model employs two length scales, i.e., pre-transition length scale and turbulent length scale pertaining to the regions upstream and the downstream, respectively, and a universal model of stream-wise intermittency variation is used as a function bridging the pre-transition region and the fully turbulent region. The proposed model is applied to calculate three benchmark cases of the transitional boundary layer flows with different free-stream turbulent intensity (1%∼6%) under zero-pressure gradient. It was found that the profiles of mean velocity and turbulent intensity, local maximum of velocity fluctuations, their locations as well as the stream-wise variation of integral properties such as skin friction, shape factor and maximum velocity fluctuations are very satisfactorily predicted throughout the flow regions.
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고난류강도 자유유동에서 평판 경계층 천이의 예측을 위한 난류 모형 개발
백성구(Seong Gu Baek),임효재(Hyo Jae Lim),정명균(Myung Kyoon Chung) 한국유체기계학회 2000 유체기계 연구개발 발표회 논문집 Vol.- No.-
A modified k-ε model is proposed for calculation of transitional boundary layer flows. In order to develop the eddy viscosity model for the problem, the flow is divided into three regions; namely, pre-transition region, transition region and fully turbulent region. The pre-transition eddy-viscosity is formulated by extending the mixing length concept. In the transition region, the eddy-viscosity model employs two length scales, i.e., pre-transition length scale and turbulent length scale pertaining to the regions upstream and the downstream, respectively, and a universal model of stream-wise intermittency variation is used as a function bridging the pre-transition region and the fully turbulent region. The proposed model is applied to calculate three benchmark cases of the transitional boundary layer flows with different free-stream turbulent intensity (1%~6%) under zero-pressure gradient. It was found that the profiles of mean velocity and turbulent intensity, local maximum of velocity fluctuations, their locations as well as the stream-wise variation of integral properties such as skin friction, shape factor and maximum velocity fluctuations are very satisfactorily predicted throughout the flow regions.
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Aerosol을 이용한 Direct-Write 시스템에서 침착된 입자의 형상예측 모델에 관한 연구
박준정(Jun Jung Park),백성구(Seong Gu Baek),리광훈(Gwang Hoon Rhee) 한국전산유체공학회 2008 한국전산유체공학회지 Vol.13 No.1
Direct Write Technologies are being utilized in various industrial fields such as antennas, engineered structures, sensors and tissue engineering. With Direct Write Technologies, producing features have the mesoscale range, from 1 to 100 microns. One form of the Direct Write Technologies is based on aerosol dynamics. The shape of deposited aerosols determine the form of products in the Direct Write Technology based on aerosol dynamics. To predict shape of deposited aerosol, a prediction model is created. In this study, we estimated Line-Width and Line-Thickness from the prediction model. Results of prediction model is valid from comparison with experimental results.
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