Pipe flow

[takamori67]

Hello everyone,

I’m trying to simulate a simple pipe flow, for laminar and turbulent cases.
However, I’m having issues. For the laminar case I use the poiseuille inflow and a pressure outlet, like in the examples. But the solution looks like a free streaming jet, see image.
https://s30.postimg.org/s8zabcmu9/photo_laminar.png

Same issue with the turbulent case. Here I use turbulence models and the block profile from the nozzle3d example. See image.
https://s30.postimg.org/uetl5uqap/photo_turbulent.png

Have you ever come across this issue or have any idea how to fix the problem?

Best,
Sumit

[robin.trunk]

Hi Sumit,

something seems to be wrong with the outlet bonudary, how do you set it?
Are the material numbers set correct, so that the boundary is applied at the right location? You can check that in the pvd file output for the geometry with Paraview.

Best
Robin

[takamori67]

Hi Robin,
I looked at the geometry file in Paraview, and indeed I found a fatal flaw. The no slip boundary extended from the wall all over the outlet. I figured this happened because the cylinder defining the pipe and the cylinder defining the outlet were fit to be touching, but without overlap. This caused the functor assinging the geometry numbers to assining a wall BC to the whole surface of the flow field(including the outlet). When the two cylinders are made to overlap by 2*latticeL, the issue is solved.

Thank you so much for your help!

Best,
Sumit

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