If you like to specify a volumetric heat source in the solid spheres, the volume of the spheres must be part of your CFX computation. It can only be a part of your CFX simulation, if the volume of the spheres is meshed and if the conjugate heat transfer (CHT) problem within the spheres is solved by CFX. So not a subdomain (in the fluid domain) is defined, but the volume of the solid spheres are defined as a separate solid domain with CHT and having a defined domain interface with the fluid domain. In the result of the simulation the temperature distribution within the volume of the solid spheres is predicted (under the cooling effect of the surrounding fluid and in dependence on flow conditions). If the volumetric heat source is uniform, than the heating can be specified just by the number of released thermal energy and the definition of it by a CFX expression is not necessary (but might be convenient).

Hopefully this is helpful to you.

Dear Dr.Frank,

Thank you for reply.

The geometry (solid and fluid) was meshed completely. Indeed I have 2 geometries as shows in the following pictures.

Exactly, like fluent!I should specify the volume of solid . But I was told that in CFX I couldn't use volumetric heat source .

Already I have two domains; solid and fluid. You say there is no need to define a subdomain in solid domain? since I saw in some CFX tutorials that in order to define heat source, we should create a subdomain in solid domain.

As I told, now I have 2 geometries and I was told that I should have just one geometry with two separate parts(solid and fluid) and then CFX itself will create solid-fluid interface. Now I was wondering if I should return to the first stage and unite these two geometry into one geometry?

Thanks

Use solid wall to specify temperatures or constant heat flux.

Can we define the material of wall in fluid domain? in my case i want to simulate hot wire heat transfer convection. My input is wall heat flux

Mohamed Salah Khelifi Touhami

1) You need to create a subdomain for the solid, if you like to specify a volumetric heat source. The solid sobdomain is occupying the same spce like the solid geometry (domain).

2) It does not matter for CFX, whether you prepare all the two geometries in one mesh file (with two parts or bodies) or whether you mesh the two geometries independently from each other an dthen you import both separate meshes into CFX one after each other. In both cases you need to define a domain interface in CFX, in order to tell CFX, that the heat transfer between the two separate domains need to get accounted for.

Regards,

Dr. Th. Frank.