[Delcraft]

Hello foamers,

I try to simulate the incompressible low-speed airflow around a blunt body (airfoil or thick plate). The difference from "classic" case of uniform flow is that the air is exhausting from a nozzle upstream of the body, you can find the image attached.

So in my case I should use farfield BC with zero velocity and an atmosperic farfield pressure. For all external boundaries (behind, upper and lower) I impose inletOutlet velocity BC type with inletValue uniform (0 0 0) as well as for the outlet. For pressure BC I use fixedValue type with zero imposed.

Another important issue is that I'm interested in transient simulation, so I use pisoFoam solver.

The problem is that as the flow from the nozzle is developing I obtain some spurious fluctuations on the farfield which become stronger and stronger and diverge my calculation (the beginning of fluctuations is also seen on the picture).

Maybe someone can help me and suggest which BC is more appropriate? Enlarging the domain doesn't help.

Thanks in advance,

Delcraft

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