[ztdep]

Dear friends;
I am conucting simulation a pipe flow with spectral collocation method for 2D ns equation.
but i do not know how to implement the outflow bc.
Could you give me some suggestions.
I have tried set p=0 and zero normal gradient for u , but it divergent.
Regards

[FMDenaro]

how do you implement the spectral method without the periodic direction?

[ztdep]

Originally Posted by FMDenaro

how do you implement the spectral method without the periodic direction?

Dear friends:
I use pseudo-spectral method, so there are no periodic direction in the problem.

[FMDenaro]

have you checked that the divergence-free constraint is satisfied everywhere?

[ztdep]

Originally Posted by FMDenaro

have you checked that the divergence-free constraint is satisfied everywhere?

Dear friends:
Thank you very much for your feedback. I use the projection method of second order stiffly stable shceme of KARNIADAKIS with a high order pressure boundary conditions.
My code work ok for the reglarized cavit problems with the first kind of BC for velocity , neuman BC for pressure.
But it divergent after only 5 steps with a neuman velocity outflow BC and Direchlet BC for P at outlet.

Could you please give me some further suggestions.
Regards