关于计算理想气体压力的问题
不太明白LB里,如果要计算实际的压力,应该将格子尺度的密度转换成实际密度,然后用理想气体状态方程算?还是用LB模型里隐含的密度和压力的关系,最后将LB单位的压力转换成物理空间压力的单位?回复 1# legendpan 的帖子
Eqn. (2) is incorrect: p = c_s^2 \rho, also, c_s^2 = R T.回复 2# luo@odu.edu 的帖子
sorry for mistyping Eqn.(2).c_s^2 = R T, c_s is a constant, then can temperature Tbe changed?
If I need to caculate pressure in physical unit, whether should I get it from Eqn.(1) by temperature in phsical unit ordirectly transformpressure in lattice unit into physical unit?
回复 3# legendpan 的帖子
NO -- the temperature T has to be a constant to the grid spacing is uniform.So, the temperature T has to be dealt with in a separately (by another equation). This is an inherent limitation of the LBE (so it is NOT a genuine compressible scheme). That is the point I have been talking about and getting no where. ;-} I get it. Do you mean that in Eqn. cs=R*T_1, the temperature T_1 is not the real temperatue. If I caculate temperature separately by another distribution function, I yield the real temperature, T_2. So T_2 has nothing to do with T_1. Beacuse the D2Q9 is a imcompressible model.
回复 5# legendpan 的帖子
Yes, you get that more or less right. You can read the papers by Lallemand and Luo on the analysis of this.回复 6# luo@odu.edu 的帖子
Thank you for your suggestion.
页:
[1]