How to simulate surface power density
 

I am simulating micro-fluid channel cooling, where there is a channel under the active region and flowing water in the channel may bring heat away. The power density of the active region I want to simulate is 200W/cm^2, how to implement it in CFX?　

I used to translate it to volume density by multiplying by the height of the active region. But I　recently found if the height is changed, I will get quite different result.

b.t.w. I have tried to set the boundary condition to "wall", and "source" to 200W/cm^2. But how to set the "heat transfer" model? Is it adiabatic or heat flux?

in the attachment is the the picture of my model. the green part is the active region. Thank you very much!

Have a look at the CFX tutorials for how to model heat transfer.

For the accuracy questions see FAQ: http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F

If you are applying 200W/m^2 you should be able to do this as a simple boundary condition. You do not need a source term.