Solid motion and boundary conditions
 

I am working on a flow problem that involves a moving domain. My domain is a porous medium moving at a constant speed that transports a fluid through a tapered channel. My problem is that when I activate the solid motion option in CFX, I only get realistic results with limited option of boundary conditions.

I can only use open-inlet and open-outlet or static pressure at the outlet. Everytime I try to add a velocity or mass-flow rate at the outlet, I obtain nonsense results or the model does not converge.

Does anyone know if these two boundaries, velocity and mass flow rate, need a special treatment for a domain in motion?

Thanks

I don't think the Solid Motion option is suitable for this case, since it doesn't actually move the solid. Take a look at the documentation for this option. It's used to transport energy in a solid domain, so there's no fluid transport.

Thanks for the info stumpy. I read the section of solid motion and here is what it says:

''The solid motion model does not involve changing the mesh. Instead, motion of the solid is simulated by imposing a velocity field in the solid domain. The velocity field causes the advection of energy and Additional Variables as applicable.''

I do not want to add a moving mesh to my problem, because the problem itself is already very complex. I think that adding a velocity field is a good simplification for my model, but I haven't found more information dealing with boundary conditions for flow in the case of a moving domain. There is some info for the boundaries in the energy equation, but not much for flow.

Do you know about a tutorial or guidelines in the manual that explain this topic in more detail?

Hello John,

I am working on the same problem you did before. So I am facing some problems you might encounter when you were working on this topic. Could you please give me some advice on the setting of solid motion and anisotropic permeability if you can see this message. Thank you very much!