Multiple boundaries selected at once for B. C
 

I have 5 inlets, the total mass flow rate is 0.5 kg/s. What happens if I name all 5 inlets as just inlet and give a single value of 0.5 kg/s. Will it take 0.5 kg/s for all inlets individually or will it divide among the participating inlets?

I would say: "Give it a try".


The answer is that the total flow of all inlets will be 0.5 kg/s.
CFX sees the 5 mesh-surfaces as 1 boundary and it will try to fullfill your setting: 0.5 kg/s in total through that boundary

Using precise vocabulary avoids confusion,

In ANSYS CFX, a mass flow inlet boundary condition imposes a uniform mass flux on each face of the mesh selected for the inlet, i.e. Mass Flow Rate / Area of the Inlet

If you had a setup with 5 separate inlets "n", you got at the maximum got 5 different mass fluxes imposed on the mesh faces of each inlet "n", i.e. Mass Flow Rate Inlet n / Area of Inlet n. Now, you are saying the total mass flow rate of the 5 inlets is 0.5 kg/s

The alternative setup of a single "macro inlet" using the same group of mesh regions used for the previous setup is "generically" a completely different model, and identically only on a specific case (leave it with you). In this new setup, the mass flux would be Total Mass Flow Rate / "Sum of the Area of Inlet n" applied uniformly over all the mesh faces selected in the group.

Hope the above helps