Unexpected high pressure point and convergence issue #31119
Replies: 2 comments 36 replies
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Hello Do you have skewness-correction turned on? Your mesh is made of tets right? |
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Hello, Thank you for the suggestions. I am trying to make the flow model work without energy equations. But I noticed that it converges when I turn off the two_term_boundary_expansion and do not include "skewness correction". So when I add one of these two to fix the problem of high pressure concentration (the original issue), it does not converge. And when I tested the input file with a different mesh with a simpler structure (27 spheres), it converges without the high pressure issue. Could you give me advice what I could test to get forward? Could the mesh quality be issue or should the "skewness correction" be included only in few blocks? Or should the "derivative-size" in the configuration be adjusted (changing from 120, which I used)? |
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Question
Dear MOOSE experts,
I have been developing a 3D thermo-hydraulic model with Navier-Stokes module using incompressible finite volume. I run a transient simulation. The problems are that the model shows unexpected pressure development and slowing down with convergence. I have a cube filled with spheres (solid phase). Inside the cube, water flows in z direction from the top to the bottom through the spheres, while the side is set with no flow boundary. Please see the model showing the mesh below:
The issues are:
After around 200 time steps, the model does not converge with the given dt = 1 and continues with a reduced time step dt = 0.5. And it repeats that, slowing down the simulation. Can it be related to the first issue shown by the high pressure point?
When I reduce time step to dt = 0.01, hoping for a better convergence, the high pressure at one point even grows over time. And the pressure value gets higher than the pressure gradient range. Is it showing that the model is not stable?
I am not sure about the cause of the problems. So it would be great if I could get some tips on the issue.
Many thanks in advance!
Best regards,
Julia
Additional information
Mesh size and type: Num DOFs: 370877
Reynolds number: Re < 2.5
Discretization (finite element CG/DG, finite volume, etc): Finite volume
Models (turbulence, porous media, etc): porous media
Solver method (fully coupled, segregated, multiapps, etc): Newton
Base input you started from:
Details
Input_file
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