Constant Heat Flux Boundary Condition
 

Hello,

I recently started using Ansys FLUENT. I have made a solid body and the internal volume of the solid i have defined as the fluid where i have to do the analysis. So i have suppressed my solid part and imported the fluid domain into fluent for analysis.
I have to give a Constant heat flux boundary condition on the walls, but i have noticed that the temperature begins to rise after a time t+deltat as its a transient case.
My problem has number of tubes fitted onto something, and i have to apply the heat flux condition on those tubes. buoyancy effect is also accounted just like the natural convection stuff. that means, some flow will happen downward and some tries to go upward due to the heat provided by the flux.
so why the temperature on wall keeps on increasing????