[minecraftgp]

Hi foamers,

I know wiki https://en.wikipedia.org/wiki/Turbulence_kinetic_energy gives equations on k and epsilon based on the inlet velocity and the pipe hydraulic diameter.

However in my case, I am modeling a buoyant flow cased by a heat source in a sealed room using buoyantBoussinesqPimplefoam,and there is no inlet and therefore the inlet velocity and hydraulic diameter do not exist. Is it still able to calculate k and epsilon in this situation?

cheers

[Robin.Kamenicky]

Hi Pu,

indeed interesting question. Certainly you cannot define k and epsilon to be 0, this would lead to floating point error. The values calculated in the simulation are very dependent on your BCs like heat flux. If you have high heat flux, you could see quite big values. This can lead to big gradients across the domain.

As I understand the purpose of these two values is to have as accurate values as possible but they are not exact. So try to guess the most appropriate values and inspire yourself by the tutorial cases. You can try to run your calculation have a look on velocities you get and adapt your BCs.

You might try to experiment a bit and have a look whether results changes with various values or only convergence time changes.

Well, I have not probably given to you an answer you wanted. I have just a limited experience which I can share. Somebody else might add a note.

Kind regards,
Robin