Temperature in rhoSimpleFoam
 

Hi all,

Does anybody know how temperature is handled in rhoSimpleFoam? I have a semi-complicated simulation that runs really well and I am getting great results for pressure and velocity but the temperature profile seems quite wrong. From the rhoSimpleFoam.C files I couldn't figure if enthalpy is taking care of temperature.

Basically, this might be stupid but I have no clue how temperature is solved for in rhoSimpleFoam or a simple loop in OF. Can somebody give me some insights?

Thanks a million,
~Ammar.

rhoSimpleFoam
 

Hello!

I am facing the same problem. I try to simulate a radial compressor with pressure ratio about 2. I can not see any temperature rise. This behaviour is unphysical. OF2.3.
Does anyone have a hint?

Regards, JCW

hello,
take a look at http://cfd.direct/openfoam/energy-equation/
... and also the source file EEqn.H for rhoSimpleFoam.

what did you use in you thermophysicalProperties ? enthalpy or internal energy ?

regards,
olivier

Ok, I think I understand now ...
I observed same problem with a calculation of a centrifugal compressor.

OpenFOAM-v2006
Geometry: Centrifugal compressor, only one blade passage with cyclic/cyclicAMI (with diffuser vanedless and without volute)
BCs: flowRateInletVelocity with fixedValue temperature inlet and fixedValue pressure outlet
MRF model
Turbulence: kOmegaSST
Thermophysical: hePsiThermo/heRhoThermo, pureMixture, transport const, hConst, perfectGas, sensibleInternalEnergy/Enthalpy
Solvers: rhoSimpleFoam, rhoCentralFoam, sonicFoam

The pressure increased as expected at the exit but not the temperature which seems remain almost constant.

So is this due to the viscous heating term missing in the energy equation? And probably the most important question: Why OpenFOAM doesn't include this term in energy equation?

It seems that lot of people is facing about this problem, see:

• https://www.cfd-online.com/Forums/op...ible-flow.html
• https://www.cfd-online.com/Forums/op...machinery.html
• https://www.cfd-online.com/Forums/op...ompressor.html

Hi,

It is usually not important for a lot of flows, but it is available via fvOptions in the OpenFOAM.com variants:

viscous dissipation fvOption

I do remember I once created something myself many years ago, but I would use that fvOption if I need it again.

Cheers,
Tom

Thanks a lot! It's better :) behaviour is much more phyisical, I haven't my temperature level I have expected but I will continue to look for it.