[Sobhan]

Greeting,
I have a question about the addressing of non-boundary surface in Pre Processor.
so I want to calculate "normal z" or "area_z" variables either in 3D subdomain or address “normal z” /”area_z” on 2D non boundary surface, which are calculating in every time step.
it means normal z on e.g. the calculating free surface of fluid, which is varying in every time step.
I can show the normal vectors in post processing CFD Post (choosing variable on Iso Surface), but the question is, how can I define such Iso surface in Pre-Processor and use it for loading during the solving process?


As background:
I try to simulate laser absorption on the free surface of molten pool (during welding process). The free surface was calculated via VOF method.
The laser is implemented via Monte Carlo method.
The absorption coefficient on the surface of molten pool depends on the curvature of free surface.
So I have a table of variation of absorption coefficient due angle of laser beam with the curvature of molten pool free surface. SO I want to define specification of the Iso surface in pre Processing to calculate its normal angle with the laser beam


Thank you in advance

[ghorrocks]

All I can think of is to take the gradient of the volume fraction field and make the absorption coefficient a function of the gradient, but include a function which sets the absorption coefficient to zero if the volume fraction is less than 0.5. Will this do what you are looking for?

[Sobhan]

Originally Posted by ghorrocks

All I can think of is to take the gradient of the volume fraction field and make the absorption coefficient a function of the gradient, but include a function which sets the absorption coefficient to zero if the volume fraction is less than 0.5. Will this do what you are looking for?

Dear Horrocks,
Thank you for your answer.
I implemented the gradient and it works. so wir get the normals.
Best regards
Sobhan