perfect gas and buoyancy!?

[Koske]

hi,

i simulate a coupled navier-stokes/heat equation problem.
and i set two settings (my fault) which i thought cant be at the same time.

for the material i set perfect gas as compressibility model.
and as a body force i set boussinesq = true.

now my question is: is one of them dominant in the calculation, so that it is for example a boussinesq approximation and the other setting is ignored? or is it possible to choose both at the same time?

thx martin

[Juha]

Hi,

i'm afraid you can set them both at the same time without notice, doesn't usually make much sense though...
DId you also have "Heat Expansion Coefficient" set? Without it the Boussinsq model does not have any effect.
-Juha

[Koske]

hi,

i use air(room temperature) as material, so a heat expansion coefficient is set.
i know that it makes no sense, it was just my fault that i set both.

because of the fact that the results look good, i think the boussinesq takes effect
and the perfect gas law not, so my simulation is incompressible.

martin

[Juha]

HI,

well in a sense i guess the case is OK, as you probably don't include body force directly,
but only through the Boussinesq flag. Otherwise the ideal gas law applies and your
flow is indeed compressible.

Juha