coupled solver (again)
 

i know i already open a post about this argument, but i didn't have any answer, so i try again...sorry:

hi to all users,
my problem is about the use of coupled solver.
I have a rectangular duct of porous media, the top surface is heated with a heat flux, the bottom surface is adiabatic. if we use the segregated solver we don't have any problem, i obtain the convergence of the solution. While if i use the coupled solver with the same model (our boundary condition is the inlet velocity) i don't obtain the convergence of the solution; in particulary i find that the temperture field is not reasonable and the outlet mass flow (with the iterations) goes from the right value (the same of the inlet mass flow) to zero.

i don't understand why i have two different solution between the two solver.

P.S.: I have to use the coupled solver because my model need to use it (i have to use the gradient of temperature ).

Sorry for my English.
Thank to all.

Best Regards