Choice of the turbulence model and mesh near walls

[jgd23]

Hello,

I start to modelize an after heater furnace in 3D. It's a test case with simplified geometry and arbitrary input parameters.
The furnace is composed of a gas burner with high velocity (inlet), electrical heaters (modelize in syrthes with volumic heat source) and two outlets (atmospheric pressure). The hot fluid flux heat directly a solid charge in front of the inlet (See attached schematic 2D of the furnace)
In a first approximation, I neglect the natural convection, assuming that the forced convection is larger. I neglect also the gas radiation assuming that the gas enter in the domain at T_hot and v_in=100 m/s. My goal is to compute a steady stream in the furnace and calculation the temperature distribution using a frozen velocity and pressures fields (CS and syrthes coupled).

My question is about the choice of the turbulence model because I have, in the same model, high Reynolds (where the gas velocity is high in the inlet canal and on the solid charge) but I have also some recirculating fluid stream where the Reynolds number can be low (in the corners of the furnace).

I think that I have to use a k-w model (low Re number) where the mesh first cell close to the walls must be < y+=1. I have to adapt manually the boundary layer mesh in function of Reynolds number.
Have I another alternative less sensitive with the mesh first cell distance in the choice of the turbulence model ?

Best regards

Julien

[Yvan Fournier]

Hello,

I'm not too sure about the best model. Our turbulence specialists are not too fond of k-omega, and often prefer RSM, but the work described in one of this year's user meeting posters (see http://code-saturne.org/cms/sites/defau ... ition-2016) is not integrated yet in the mainline code, so even if that would be a good fit, it is too early to recommend that...

I'll suggest other developers to check the forum for your question. Otherwise, did you check the recommendations in the documentation part of this web site for best practices ? You might find a few additional suggestions.

Regards,

Yvan