Hello,

Im creating a case whera a fluid of incompressible fluid is beeing heated from a constant heat flux from one of the walls.

As temperature B.C for that wall I have put upp the condition fixed gradien (uniform) which works fine. Th problem is which value to use for the konstant temperature gradient. Im using the formula deltaT=q''/kEff. The problem is to find a value for the constant kEff=kTurb+k (where kTurb is the problem) Deos anyone know how I can find this value out?

Thanks
/Erik

[Anne Lincke]

As far as I know k_eff = v/Pr + nu_t/Prt

where nu is the kinematic viscosity, nu_t the turbulent viscosity and Pr and Pr_t Prandtl-number, laminar and turbulent, respectively.

[Tiffany]

Hi Anne and Erik,

I'm new to OpenFOAM and CFD. I'm trying to determine the heat transfer from a problem I setup. It is a heated concentric cylinder problem that I solved with the k-epsilon model with buoyantBoussinesqPimpleFoam. It appears to solve for kappat (kinematic turbulent thermal conductivity), k (turbulent kinetic energy), nut (turbulent viscosity), alphat (thermal diffusivity), epsilon (kinetic energy dissipation rate), and a few others. I'm a little lost as to what equation to use to get the effective thermal conductivity though. If I can get k_eff, I have a formula for my particular setup to get the heat transfer. But I'm stuck on how to get k_eff. Any suggestions?

[Anne Lincke]

Hey Tiffany,


kappa_eff is the sum of kappa_t and kappa.
The ladder is computed from nu/Pr which are defined in constant/transportProperties.

Kind Regards
Anne