周期性加热Poiseuille-Rayleigh-Benard流动中局部行波的研究

该文通过二维流体力学基本方程组的数值模拟,研究了水平来流和周期性加热对腔体内流体的运动和动力学特性的影响。当相对瑞利数r(28)9时,随着水平来流雷诺数Re逐渐增加,腔体内的流体发生三种不同的运动,即局部对流运动、局部行波运动和水平流运动。对局部行波运动的周期pT进行研究,局部行波运动的稳定周期随水平来流雷诺数的增大而减小,随相对瑞利数的减小而减小;相对瑞利数越小,稳定周期随水平来流雷诺数变化的增长率越大。局部行波运动的区间(35)Re依赖水平来流雷诺数的强度,当水平来流雷诺数Re大于(35)Re的上限时流体为水平流运动,而当水平来流雷诺数Re小于(35)Re的下限时流体为局部对流运动;对于不同的相对瑞利数r,局部行波运动的区间(35)Re是不同的。随着水平来流雷诺数增大,发现腔体内上游行波区域对流圈的减少速度比下游行波区域更快。

Localized traveling waves in Poiseuille-Rayleigh-Benard flows under periodic heating

By using a two-dimensional numerical simulation of the fully hydrodynamic equations,the effects of horizontal flow and periodic heating on the fluid motion and the dynamic characteristics in the cavity are studied.For the reduced Rayleigh number r =9,the system has three different kinds of motion with increasing horizontal flow Reynolds number Re in the cavity,such as,localized convection motion,localized traveling wave motion and horizontal flow motion.By studying the period of localized traveling wave motion,the stable period of localized traveling wave motion reduces with increasing Re or reducing r.For a small reduced Rayleigh number,increasing rate of the stable period varying with horizontal flow Reynolds number is larger than that for a lager reduced Rayleigh number.The range of localized traveling wave motion ⊿Re depends on the intensity of the horizontal flow Reynolds number,system carries on horizontal flow motion when Re is larger than the upper limit of ⊿Re.However,system carries on localized convection motion when Re is less than the lower limit of ⊿Re.The range of localized traveling wave motion ⊿Re is different for different reduced Rayleigh number r.With the increase of horizontal flow Reynolds number,it is found that the decrease rate of convection cell in the upstream traveling wave region is quicker than that in the downstream traveling wave region.