急问：RElAX(LTLS,FALSDT,1.00000E+00)是什么意思？是如何设置的？

xlfd

急问：RElAX(LTLS,FALSDT,1.00000E+00)是什么意思？是如何设置的？
谢谢！

galary1979

设置松弛因子啊，LTLS是离开壁面的距离，FALSDT是虚拟时间步长法

xlfd

在VR的numbers什么地方设，才能有效如何设？才能反应到q1文件中？
谢谢！
galary1979 请帮忙在程序上看看！
急！

galary1979

RELAX(variable name,FALSDT,false time step), adds a source in each cell equal to the mass in the cell divided by the size of the time step.
在第17组中设置这个命令的,正的松弛因子是采用虚拟时间步长方法的,但是具体怎么设置为多大,我还没有研究过,也没有什么经验提供

galary1979

最基本的是(可以查看polis中的相关介绍)
Its effect is to add to the phi-balance for each cell a source equal to:
(latest_phi - next_phi) * (mass in cell) / DTFALS(phi)
where latest_phi is the current value of the variable being solved for, and next_phi is that which it will take after adjustment.
This has the effect of making next_phi very close to latest_phi when DTFALS is large, so that changes can occur only after many repetitions of the adjustment process.
A value of DTFALS=1.E-20 would prevent change entirely on many machines, a fact which it is sometimes convenient to exploit, for example when seeking to understand the causes of divergence.