If your fluid and solid volumes are meshed independently (2 separate mesh files), than it should be straight forward in CFX. Read in each of the two meshes, define them as a domain in CFX and use the icon for interface creation in the top row of icons.

I think that it can be done in one mesh file, if the two volumes have been separated during geometry preparation as two distinct bodies and each of them has its own mesh. Than the names of the two volumetric regions should be accessible in CFX for the same operations as well.

Define the interfaces in the meshing model as interface 1 and interface 2 and manually select the interfaces in CFX by clicking mesh interfaces tab . automatic interface selection can also be done,cross check whether the interface connections are correct,

Dear Dr.Frank,

I just have one mesh file.

Dear Aravinth,

Yes I have to define for each interface, 2 interface sides, one for fluid and one for solid. Now my problem is how to define such interface for spheres since as you see in the following pic, 4 spheres are enclosed with fluid. so the outer surface should be an interface for fluid and inner surface should an interface for solid.

Thanks.

And what if spheres are hollow? The hollow part will be part of enclosure?