Flow in a pipe: stability issues (4 replies)

Hello,

I am trying to set-a flow in a 3D circular pipe based one the aneurysm bounceback case (especially for the boundary conditions).

I have a poiseuille flow at the inlet with a Reynolds number of around 400 and a pressure boundary at the outlet. I use bounceback boundary conditions for the wall.

The case runs but rapidly I get stability issues: non physical velocities appear along the wall and propagate in the flow until a got NANs !

I checked my stability parameters which seems right (U lb = 0.01). I run sensibilities for:
- different lattices from around 1 to 40 millions (i. e. from 20 to 160 cells in a diameter)
- different models: BGK or smagorinsky BGK model
- different initializations: with default or poiseuille velocity initialization

Does everyone would have any idea of what is wrong, or what may set this right ? I am just out of ideas.

Thanks in advance,
Julien