Time Scalings of Entropy Transfer Process in Free Convection

概要

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To study one elementary process of entropy cascade in hard turbulence, we propose a shellznodel which governs the temperature gradient rotated throtugh the angle +'!., ')(. ; (O.T, -8.T),and the velocity gradient, i.e., strain rates. This model is based on the correspondence of thedynamics of ')(, in a two-dimensional free convection system to that of the vorticity in a three-dimensional Navier-Stokes system. We obtain the following results: l) A steady solution whichsatisfies Bolgiano-Obukhov (BO) scaling in the viscous case exists. 2) After a small disturbanceof large scale is added to the steady solution, time series of the modes in the inertial rangebecome similar to each other under the proper scaling, and each mode has its own characteristictime predicted by BO scaling. 3) When the same disturbance is added to the null state, themodes also evolve similarly in the inertial range. The characteristic times of the modes are,however, explained by a dimensional analysis based on total entropy which is different from BOscaling.
社団法人日本物理学会の論文
1998-02-15