You should improve your understanding of heat transfer basics.

Convective Heat Transfer > q = h(T - Tb)

where q = heat flux

h = film coefficient

T = surface temperature

Tb = temperature of bulk fluid on surface.

Do you see that convective heat flux *depends on the **surface **temperature *T?

A heat flux boundary condition means the value of q is a constant, *regardless of the surface temperature* T.

It is mathematically impossible to have both a convection boundary condition and a heat flux boundary condition on the same surface.

If you know the film coefficient, h, you could use Steady State Thermal analysis instead of a Fluent Model to simulate the convective heat transfer.