平均せん断が運動量・熱輸送の素過程に及ぼす影響

概要

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Direct numerical simulations are performed to investigate the effects of mean shear and mean temperature gradient on the structure of homogeneous turbulence and related heat transport. First, homogeneously sheared turbulence with mean temperature gradient is evolved from the initial condition of isotropic turbulence. After the flow becomes fully developed, the mean shear and temperature gradient are removed and the succeeding return-to-isotropy process is examined in detail. It is found that the removal of mean shear gravely affects the decaying processes of turbulent shear stress and heat flux. In the spectral energy balance of Reynolds shear stress and hear flux, the non-linear term is found to transfer energy from high to low wave-numbers, thus indicating the counter-gradient transfer of heat and momentum occurs at high wave-numbers. And the visualization of instantaneous structures reveal that the counter-gradient transfer is uniquely associated with the longitudinal vortex tubes.
一般社団法人日本機械学会の論文
1998-02-25