Boundary Conditions: Scalar Transport Flux

Atoom · June 5, 2014, 02:47

Dear OpenFoam Community,

I have a case with a known velocity field. Now I want to solve the Scalar Transport equations within the domain. It works fine, I only have a problem regarding the inlet boundary. It is a box the other walls have no-slip conditions and continuity is fulfilled.

The inlet boundary has the slip condition and a fixed concentration. When solving the equations the flux now should be J = -Dgrad(C), but I also want to add the advective flux at this boundary. Otherwise, the scalar has to first diffuse in, before it is transported due to advection. The flow itself is driven by a pressure gradient at the surface.

Is the boundary condition advective the right one? Because this leads to a divergence of the Model. Obviously, I don't know how to set it up correctly. I used it for U and set phi =phi;

Thank you for your help!

Soeren

Atoom · June 5, 2014, 02:55

Ok, I think I solved the problem by setting the boundary condition for the Scalar to advective with a fixed value and U as described.

June 5, 2014, 02:47	Boundary Conditions: Scalar Transport Flux	#1
Atoom New Member Soeren Join Date: Oct 2012 Posts: 11 Rep Power: 13	Dear OpenFoam Community, I have a case with a known velocity field. Now I want to solve the Scalar Transport equations within the domain. It works fine, I only have a problem regarding the inlet boundary. It is a box the other walls have no-slip conditions and continuity is fulfilled. The inlet boundary has the slip condition and a fixed concentration. When solving the equations the flux now should be J = -Dgrad(C), but I also want to add the advective flux at this boundary. Otherwise, the scalar has to first diffuse in, before it is transported due to advection. The flow itself is driven by a pressure gradient at the surface. Is the boundary condition advective the right one? Because this leads to a divergence of the Model. Obviously, I don't know how to set it up correctly. I used it for U and set phi =phi; Thank you for your help! Soeren

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June 5, 2014, 02:55		#2
Atoom New Member Soeren Join Date: Oct 2012 Posts: 11 Rep Power: 13	Ok, I think I solved the problem by setting the boundary condition for the Scalar to advective with a fixed value and U as described.