wallHeatFlux with radiation
 

Hi Everyone,

I got a bit trouble in Openfoam with heat transfer problem. Basically, I need to specify heatflux boundary condition which is same with Fluent. However, I didn't find this boundary condition in standard Openfoam. I found a "externalWallHeatFluxTemperature", but that is for compressible flow with solid. My case is incompressible flow with buoyantboussinesqsimplefoam solver.

Then, luckily, I download a wallHeatFlux boundary condition from foam contribution.
https://openfoamwiki.net/index.php/Contrib/wallHeatFlux


However, this one is not included radiation. So, I test it for radiation off case, the results is almost identical with Fluent.

Then, I added radiation in it. So basically, I just added qr in the equation

gradient() = (HeatFlux_ - qr_)/(alphaEffW * Cp0.value() * rho0.value() );

The code is working when radiation on. However, it then crashed very soon as G (radiation incident), T temperature are goto very high number like E100 then crashed.

Does anyone know anything about Heatflux boundary condition to give me any suggestion?

Thanks a lot.

Hi Guys,

I added relexation factor for qr in this case, and it then working. However, the relaxation factor is related to qr magnitude when qr is high, very low relaxation is needed like 1E-5. However, this will make simulation converge very very slow.

Does anyone has any idea to improve convergence?

Thanks a lot.