고난류강도 자유유동에서 평판 경계층 천이의 예측을 위한 난류 모형 개발

Development of k-$\epsilon$ model for prediction of transition in flat plate under free stream with high intensity

  • 백성구 (한국과학기술원 대학원 기계공학과) ;
  • 임효재 (호서대학교 기계공학과) ;
  • 정명균 (한국과학기술원 기계공학과)
  • 발행 : 2000.12.01

초록

A modified k-$\epsilon$ 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 university 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 mom 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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