摆动行波及其向定常对流的过渡

Undulation travelling wave and its transition to stationary overturning convection

利用Simple算法对流体力学基本方程组进行了数值模拟,探讨了矩形腔体具有强Soret效应的混合流体对流的摆动行波斑图的动力学特性及其向定常对流过渡的动力学特性。结果说明,在较大的相对瑞利数变化范围内存在着摆动行波。摆动行波的摆动周期和摆动幅度随着相对瑞利数的增加而减小。摆动行波的当地波数随着时间和空间不断变化,当地波长随着时间被压缩或者伸长。当超过了摆动行波存在的上限后,系统首先由小扰动状态发展成摆动行波,然后经过一段时间的过渡再发展成定常对流。随着相对瑞利数的增加,从摆动行波过渡到定常对流的时间变短。

The numerical simulations are made by solving the basical equations of hydrodynamics,and the dynamics of undulation travelling wave pattern in binary fluid convection with strong Soret effect in a rectangular cell and its transition to stationary overturning convection are studied.The result shows that an undulation travelling wave exists in the large range of relative Rayleigh number.The oscillation period and amplitude of the undulation travelling wave decrease with the increase of the relative Rayleigh number.The local wave number of the undulation travelling wave is changed with time and space,and the local wavelength is compressed or stretched with time.When the upper critical value of existence of the undulation travelling wave is exceeded,the system is first developed to the undulation travelling wave from a small perturbation state,and the system is then developed into stationary overturning convection after a period of transition.With the increase of the relative Rayleigh number,the time of the transition from the undulation travelling wave to the stationary overturning convection become shorter.