Source terms and heat source
 

Hello everyone,
I am working on natural convection in fluent.
I have a cubic volume with fluid air. and a seperate wall surface inside the volume and want to locate 500 W/m2 heat source on that wall surface. but my problem is that in boundary condition panel for wall surface the heat generation rate is to be inputed in W/m3 and the same problem in energy source terms in fluid boundary condition panel.
So can anyone suggest me that how to locate this much heat source at that wall surface.

Thank you in advance.......