Cylinder2d: zero-gradient boundary condition

Palabos General
#1

Hello,

In cylinder2d example we have a zero-gradient boundary condition for the outlet. I am wondering why we use this boundary condition and why we can’t just use the Dirichlet velocity boundary condition like we did for the tutorial 1_5 with a 2D poiseulle flow?

Thanks,

Karl Gardner

#2

Hi,

I guess it is just a matter of choice… I don’t see any contradiction, you can use both, but you will get different models.

Cheers,

Francesco