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Pressure boundary conditions
Posted Mar 23, 2011, 7:08 a.m. EDT Fluid & Heat, Computational Fluid Dynamics (CFD) Version 5.2 2 Replies
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Hi everyone,
I want to simulate a duct flow in which an unsteady pressure boundary condition is to be specified at inlet and constant pressure boundary condition at exit of a simple straight cylindrical duct.I tried to handle this problem by first attempting to solve for a constant pressure condition at inlet and exit (two different pressure values) and thought of using that solution as initial condition for my unsteady problem.But when trying to solve the steady problem itself, solution is not converging and the following error message is being displayed.
"Failed to find a solution:
Divergence of the linear iterations.
Returned solution has not converged"
I tried to solve the problem by increasing the number of Newtons iteration as well,still I couldn't rectify this error.Also is there anything special to be taken care of while trying to solve a problem having pressure boundary conditions only without a velocity boundary condition?Can someone help me in this regard..
Thanks in advance!
SM Ananth
I want to simulate a duct flow in which an unsteady pressure boundary condition is to be specified at inlet and constant pressure boundary condition at exit of a simple straight cylindrical duct.I tried to handle this problem by first attempting to solve for a constant pressure condition at inlet and exit (two different pressure values) and thought of using that solution as initial condition for my unsteady problem.But when trying to solve the steady problem itself, solution is not converging and the following error message is being displayed.
"Failed to find a solution:
Divergence of the linear iterations.
Returned solution has not converged"
I tried to solve the problem by increasing the number of Newtons iteration as well,still I couldn't rectify this error.Also is there anything special to be taken care of while trying to solve a problem having pressure boundary conditions only without a velocity boundary condition?Can someone help me in this regard..
Thanks in advance!
SM Ananth
2 Replies Last Post Nov 28, 2016, 4:18 a.m. EST
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Posted:
1 decade ago
Hi
my experience is that one should always give some good initial conditions, define already a flow and a pressure drop in the tube, estimated from "rulr of thumb" values. These are mostly better tan the default "0" for all values ;)
--
Good luck
Ivar
my experience is that one should always give some good initial conditions, define already a flow and a pressure drop in the tube, estimated from "rulr of thumb" values. These are mostly better tan the default "0" for all values ;)
--
Good luck
Ivar
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Posted:
8 years ago
Dear Ivar,
how would you implement that? Setting two boundary conditions for inlet with pressure AND velocity? How would you set the pressure drop over the tube - set an initial domain BC?
Looking forward to your answers.
Regards, Kristina
how would you implement that? Setting two boundary conditions for inlet with pressure AND velocity? How would you set the pressure drop over the tube - set an initial domain BC?
Looking forward to your answers.
Regards, Kristina