[COMSOL_Users] Time dependent NS Equ. not converging

[[e-mail] [COMSOL_Users]]

Hi



I am modelling a laminar flow problem in a micro channel (2D asymmetric)
in a transient mode. My model works well but when I change the inlet boundary condition to velocity instead of pressure it does not converge! the outlet is a pressure boundary condiiton


I get below message

Nonlinear solver did not converge.
Maximum number of Newton iterations reached.
Time : 0
Last time step is not converged.

Also when I change the viscosity to non newtonian, my model only works with velocity inlet boundary condition and not the pressure?

is there fundamental problem here ? can you please comment?

Best regards

[akmal hidayat [e-mail] [COMSOL_Users]]

Hi mansouri,

1. check the BC again
2. increase iteration steps
3. decrease the time steps



"***@yahoo.com [COMSOL_Users]" <***@yahoogroups.com> schrieb am 15:51 Sonntag, 8.Juni 2014:



 
Hi


I am modelling a laminar flow problem in a micro channel (2D asymmetric)
in a transient mode. My model works well but when I change the inlet boundary condition to velocity instead of pressure it does notconverge! the outlet is a pressure boundary condiiton 

I get below message

Nonlinear solver did not converge.
Maximum number of Newton iterations reached.
Time : 0
Last time step is not converged.

Also when I change the viscosity to non newtonian, my model only works with velocity inlet boundary condition and not the pressure?

is there fundamental problem here ? can you please comment?

Best regards

[[e-mail] [COMSOL_Users]]

I am also facing the same problem and the same message shows.