Non-isothermal incompressible LES in OpenFOAM
 

Hi,

I was wondering which solver should we use to simulate a 'Non-isothermal incompressible LES in OpenFOAM' without the boussinesq approximation. I understand there is a well laid out procedure for flows with 'boussinesq approximation':

http://openfoamwiki.net/index.php/Bu...sinesqPisoFoam

We would like to use temperature dependent fluid properties for the LES simulation (ideal gas for density of good enough). Any information would be of great help.

Thanks for all the help.

Sagnik

If you want temperature dependent fluid properties through ideal gas law, it will no longer be incompressible. The point of the Boussinesq approach is to avoid variable density (and the compressible formulation) and instead "model" density changes through a body force term dependent on temperature.

The rule of thumb for Boussinesq validity is

Your alternative is to explore the buoyantPimpleFoam solver which has variable density but as I mentioned will be compressible.

Yes, very true. I understand that you are suggesting 'buoyantPimpleFoam' solver. Would it be possible for you to suggest us a good reference work with OpenFOAM in this regard !

Thanks for all the help and inputs.

Sagnik

If you check out the buoyantPimpleFoam source you will see it's already capable of using LES. Switching between RAS and LES is handled in the constant/turbulenceProperties dictionary. Then add/modify an constant/LESProperties dictionary to define the LES model you want to use.

Since it's compressible you may want to refer to one of the existing LES compressible tutorials for model and BC options.

Good luck

Hi all,

just for better understanding:

if the density is only a function of temperature and composition, then the flow is incompressible but the density can change!!!! (with temperature and composition). In an compressible flow, the denisty is a function of pressure. If the Mach number is higer then lets say 0.3 , we have to care about the pressure.

The most people think that incompressible is if density do not change. This is wrong! This kind of flow is constant density flow.

In my opinion it is very confusing in OpenFoam, that some solvers are called compressible and incompressible. For example buoyantPimpleFoam can be used for compressible and incompressible flow. It depends on which equation of state you use in thermophysicalProperties dictionary. If you choose:

equationOfState incompressiblePerfectGas;

then the flow is incompressible. If you choose:

equationOfState perfectGas;

then the flow is compressible.

In both cases the density can change.

kind regards
Florian

Hi drmarcoguevara,

bouyantPimpleFoam and bouyantSimpleFoam should be able to handle non-isothermal incompressible flow. But I am very intrested in the code you mentioned. Could you please upload the code in the forum??

Then we can verificate the code. This should be helpfull for you as well.

If this is impossible, could you please send me the code:
ries@ekt.tu-darmstadt.de

kind regards
Florian

hi drmarcoguevara,

could you please share your code with us

Thanks