code_saturne User's Forum

Can somebody maybe point out the major difference between the low-mach algorithm idilat=3 vs the compressible module. And is there any documentation for the low-mach algorithm?

Thanks.

Hello,

you first should take a look at the Mach number, if M > 0.3, the compressible module should be used.

If M < 0.3, but the density variations are such that and the pressure variations are rather slow, you can consider using the low-Mach algorithm. Typically if your flow is in a closed domain with a slowly increasing pressure.

Regards,

Erwan Le Coupanec

I guess my question was a bit to general. I of course know that below a Mach number of 0.3 it is considered to be incompressible and vice versa. Actually I did run calculations with both possibilities. The problem with the idilat variant is that it highly instable, because I wanna model the density with the ideal gas law which obviously couples the density and the pressure. The big pressure differences actually arises due to a rotating reference frame. I actually may have found some workaround for that now by not using the actual pressure but the kinetic energy which is the actual reason for the pressure differences.