how to set density as boussinesq?
 

hello I want solve nature convection problem and I do not know how I can set density as boussinesq in CFX please help ?

Thanks

In the material properties define a thermal expansivity, under Buoyancy properties. Then if you select a buoyancy model in the domain you will be using the Boussinesq buoyancy model.

Yes, as long as you have defined constant density. If you define variable density or use ideal/real gas, then the full buoyancy model will be used.