[Peter023]

Dear Fellows:

I have quite challenging problem which is the solar air collector simulation.

Basically, the core is the natural convection of air in an enclosed space with bottom inlet boundary and top outlet boundary.

The most significant complication lies in the free convection simulation because, unfortunately, the inlet air velocity or inlet mass flow rate is unknown. Only air inlet temperature and temperature of the heat absorber is known. Therefore I cannot use the velocity inlet or mass inlet boundary.

But in case of pressure inlet and pressure outlet boundary conditions, there are many reversed flow faces and and the task does not converge, in case of steady state. The situation is similar in case of transient simulation.

I think, the problem lies in the wrong boundary setting. The inclination of the air collector is 45 deg. or it is positioned vertically.

Can anyone help me with this problem, please.

Thanks for any advice in advance.

Peter.