关于不可压湍流涉及温度变化时，密度是否变化的问题

littlefox

书上说的是不可压流体密度视为常数，如果有温度变化了？就是算流动时，计算的马赫数小于0.3，为不可压流动，但是涉及到换热，温度肯定会变化的，密度还是不变的吗？但是在看ansys帮助文件（其自带的）时，有这样一句话，很疑惑In an incompressible flow, density variations can drive the flow only through gravitational acceleration. Temperature changes cause variations of density.关键是最后一句，上面说温度的变化引起密度变化，难道是帮助文件写错拉，还望各位不吝指教!!

lcw

温度变，当然密度变了，
不可“压”就是不随“压力”变化。

liwei

不可压是指密度的全导数为零，其在空间和时间上都是可能变的

caitao

能不能把你看的书发给我,谢啦

anyone

"温度的变化引起密度变化"应该是讲Boussinesq Approximation, 主要用与自然对流.
The Boussinesq approximation also adds a source term to the momentum equations, but the source term is independent of the density variation. The source term is a function of the temperature variation as follows:
Si = girVol( T-Tref)Beta

where Beta is the thermal expansion and is normally set to 1/Tref. As you can see, the source term is dependent on the density, but density does not have to vary to cause an effect. This approach can be used for (almost) incompressible liquids.