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파이프 유동에서의 난류물질전달에 대한 Schmidt 수의 영향
강창우(Changwoo Kang),양경수(Kyung-Soo Yang) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
Large Eddy Simulation (LES) of turbulent mass transfer in circular-pipe flow has been performed to investigate the effects of Schmidt number on turbulent mass transfer. We consider a fully developed turbulent pipe flow with a constant wall concentration. The Reynolds number under consideration is Re<SUB>τ</SUB>=500 based on the friction velocity and the pipe radius, and the Schmidt numbers are 0.71, 5, 10, 20 and 100. Dynamic subgrid-scale(SGS) models for turbulent SGS stresses and mass fluxes are employed to close the governing equations. In this investigation, we examine the reliability of the LES technique for predicting turbulent mass transfer at high-Schmidt numbers and analyze the behavior of turbulent mass diffusion from the wall at different Schmidt numbers. To show the effects of Schmidt number on turbulent mass transfer, the statistical quantities such as mean concentration profiles, concentration variance, turbulent mass fluxes, turbulent Schmidt number, and mass transfer coefficients are presented for the selected Schmidt numbers. Turbulence budgets for concentration variance and turbulent mass fluxes are computed and the effect of Schmidt number is identified. In addition, to clarify the correlation between near-wall turbulence structures and concentration fluctuation, we report an Octant analysis in the vicinity of the pipe wall.
난류 파이프 유동 내 물질전달에 대한 레이놀즈 수 영향
강창우(Changwoo Kang),양경수(Kyung-Soo Yang) 한국전산유체공학회 2012 한국전산유체공학회지 Vol.17 No.3
Large Eddy Simulation(LES) of turbulent mass transfer in fully developed turbulent pipe flow has been performed to study the effect of Reynolds number on the concentration fields at Re<SUB>T</SUB>=180, 395, 590 based on friction velocity and pipe radius. Dynamic subgrid-scale models for the turbulent subgrid-scale stresses and mass fluxes were employed to close the governing equations. Fully developed turbulent pipe flows with constant mass flux imposed at the wall are studied for Sc=0.71. The mean concentration profiles and turbulent intensities obtained from the present LES are in good agreement with the previous numerical and experimental results currently available. To show the effects of Reynolds number on the turbulent mass transfer, the mean concentration profile, root-mean-square of concentration fluctuations, turbulent mass fluxes, cross-correlation coefficient, turbulent diffusivity and turbulent Schmidt number are presented.
강창우(Changwoo Kang),양경수(Kyung-Soo Yang) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
Large eddy simulation(LES) of fully developed turbulent pipe flow has been performed to investigate the effect of Reynolds number on flow field at Re<SUB>τ</SUB>=180, 395, 590 based on friction velocity and pipe radius. A dynamic subgrid-scale model for the turbulent subgrid-scale stresses was employed to close the governing equations. The mean flow properties, mean velocity profiles and turbulent intensities obtained from the present LES are in good agreement with the previous numerical and experimental results currently available. The Reynolds number effects were observed in the mean velocity profile, root-mean-square of velocity and vorticity fluctuations, Reynolds shear stress and higher-order statistics(Skewness and Flatness factor). Furthermore, the budgets of the Reynolds stresses and turbulent kinetic energy were computed and analyzed to elucidate the effect of Reynolds number on the turbulent structures.
강창우(Changwoo Kang),양경수(Kyung-Soo Yang) 한국전산유체공학회 2012 한국전산유체공학회지 Vol.17 No.2
Direct Numerical Simulation(DNS) of turbulent mass transfer in fully developed turbulent pipe flow has been performed to study the effect of wall boundary conditions on the concentration fields at Re<SUB>τ</SUB>=180 based on friction velocity and pipe radius. Fully developed turbulent pipe flows for Sc=0.71 are studied with two different wall boundary conditions, namely, constant mass flux and constant wall concentration. The mean concentration profiles and turbulent mass fluxes obtained from the present DNS are in good agreement with the previous numerical results currently available. To investigate the effects of wall boundary condition on the turbulent mass transfer, the mean concentration profile, root-mean-square of concentration fluctuation, turbulent mass fluxes and higher-order statistics(Skewness and Flatness factor) are compared for the two cases. Furthermore, the budgets of turbulent mass fluxes and concentration variance were computed and analyzed to elucidate the effects of wall boundary conditions on the turbulent mass transfer.