I don't know if its what you looking for or encounter this type of Inlet condition before, but if not, I think its worth to take a look. https://www.openfoam.com/documentation/guides/latest/doc/guide-bcs-inlet-velocity-dfm-fsm.html https://www.openfoam.com/documentation/guides/latest/api/classFoam_1_1turbulentDFSEMInletFvPatchVectorField.html