Page 1 of 1

Total pressure is constant

Posted: Wed Jan 16, 2013 12:10 am
by bajsi
Version: CS 3.0-beta

I have a simple test case:
- a cubic meter of air with initial temp. = 0 °C,
- user law for density + gravity for convection,
- a boundary condition of 100 °C on all sides (no inlets or outlets).

The computation finishes OK - the cube heats up, but the total_pressure is constant and pressure deviates only due to hydrostatic difference. Considering that this is isochoric (constant volume) process the pressure should increase as temperature rises.
I guess my error is in user law for density "(rho = 1.293 * (273.15 / (TempC + 273.15));" it probably should use pressure as an additional factor.

Any ideas how to make this properly? Attached is a zip of mesh and settings.

Re: Total pressure is constant

Posted: Wed Jan 16, 2013 1:33 am
by Yvan Fournier
Hello,

I'll check with colleagues tomorrow, but I believe you may need to activate the compressible module for this.

Regards,

Yvan

Re: Total pressure is constant

Posted: Thu Jan 17, 2013 1:12 am
by Yvan Fournier
Hello,

The "idilat = 2" model (low-mach compressible option) might also help here.

Regards,

Yvan