I am working for complex duct problem analysed in CFX and Fluent for fixed mass flow quantity. In star-cd at inlet how the fixed quantity of mass flow in normal direction can be applied. After switching on Turb and mass flux quantity at boundary condition panel required input quantities are not available. Possible hint/suggestation from user community in this regard is highly appreciated.

Dr C.Bhasker

For incompressible flow inlet or supersonic inlet, the mass flux is fixed by specified inlet density and velocity components.

For any type of flow, you have to calculate the density and velocity for given mass flow rate. Specfy these quantities in Inlet boundary and click on Fixed Mass Flow button in the same panel of Inlet boundary.

As mentioned before, you have to calculate the massflow with the boundary-area, density and velocity (perhaps temperature), but it DOESN'T MATTER if the density and temperature is that of the physical problem or not (make a small test). StarCD calculates only a simplle mass-flow-value from this may be unrealistic quantity-values.

The benefit of this confusing method is, that you can use "fixed mass"-flow boundary (e.g. air ducts, manifolds, ...), and you can choose a (e.g. air-/wind-) velocity for aerodynamic problem with "fixed-velocity".