Hi!
I did a 3D TFM simulation of Gas and solid going though a pipe and passing through an offset choke point.
I cannot understand why if i check the y velocity component of the gas and solid, it shows that the gas and solid are recirculating up through the left side. (not in a turbulent way).
Could this be due to a problem with the Pressure outflow BC?
Any explanation for this?
Many thanks in advance
Stage2.3.mfx (11.1 KB)
I have had similar problems when my STL and mesh did not intersect perfectly. I would try slightly lengthening the y_min to say -9.51 and try again. I say this because it looks more like your gas is reflecting off of the bottom boundary, rather than passing through it. If that doesn’t work, go the other way (shorten it) in case I’m remembering this weirdness backwards. 
Thanks for the reply, making the pipe longer helped and you can see some turbulence going on where the pipe was cut!