# Fluent dynamic mesh-layering

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 April 9, 2009, 10:23 Fluent dynamic mesh-layering #1 New Member   Jack nedermans Join Date: Mar 2009 Posts: 12 Rep Power: 8 Hi, I am solving the flow though a channel opened on a piston head which is moving inside a cylinder. Here, I am using layering type dynamic mesh. I can see the mesh moving without any problem in Fluent; however, when I were to iterate the solution it gives error as "Error: divergence detected in AMG solver: pressure correction Error Object: ()" When I work with ideal gas there is no problem. But when I am to work with a fluid, such a problem occurs. Can anyone advice me anything with that? Thank you all. I am waiting from you.

 April 9, 2009, 12:19 Maybe continuity #2 New Member   Jack nedermans Join Date: Mar 2009 Posts: 12 Rep Power: 8 I think it is because of Continuity. When I use ideal gas as a fluid, Fluent goes on calculations without an error. However, when I chose a fluid, a kind of incompressible fluid, the continuity residual diverges. Would it be because of this?If so, how can I overcome this problem?

 February 24, 2010, 21:58 Ask for help #3 New Member   Sina Fardisi Join Date: Feb 2010 Posts: 3 Rep Power: 7 Hi I want to solve a similar problem and had troubles. Did you solve your issue, how? I want to solve the fluid flow in a non circular culinder-piston configuration. Originally, I would like to solve it 3D but let's discuss the 2D problem first. The cylinder walls have some curvature, for example each wall can be viewed as a 1/4 of a circle. The piston moves inside this curvilinear cylinder. My question is what is the best way to do it and how should I introduce the moving wall for the piston? Is there a good online help or a tutorial? P.s.1 I think I have to use a mesh layering but I am not sure how I should account for the motion of the piston. I know Fluent has a pre-set situation for conventional cylinder piston problem in mesh layering but how can I expand it to non circular culinder-piston. P.s.2 Do I have to use a moving wall? If yes do I have to write a UDF for it and in that case can I still use the mesh layering or I do I need re-meshing then? Thanks in Advance Sina

August 18, 2011, 09:46
#4
Senior Member

raymond
Join Date: Nov 2009
Posts: 149
Rep Power: 7
Quote:
 Originally Posted by coolengineer Hi, I am solving the flow though a channel opened on a piston head which is moving inside a cylinder. Here, I am using layering type dynamic mesh. I can see the mesh moving without any problem in Fluent; however, when I were to iterate the solution it gives error as "Error: divergence detected in AMG solver: pressure correction Error Object: ()" When I work with ideal gas there is no problem. But when I am to work with a fluid, such a problem occurs. Can anyone advice me anything with that? Thank you all. I am waiting from you.
I would like to have my model by having 'layering' scheme of dynamic mesh. Unfortunately, I am totally new in dynamic mesh and I might need your help in guiding me to have good dynamic mesh modeling which might similar with your case. My model is shown as the attachment. May I have your advise on how to do that. Pls help me. Thanks a lot.
Attached Images
 layering volume increment.jpg (89.7 KB, 70 views)

August 18, 2011, 15:18
#5
Senior Member

raymond
Join Date: Nov 2009
Posts: 149
Rep Power: 7
Quote:
 Originally Posted by coolengineer Hi, I am solving the flow though a channel opened on a piston head which is moving inside a cylinder. Here, I am using layering type dynamic mesh. I can see the mesh moving without any problem in Fluent; however, when I were to iterate the solution it gives error as "Error: divergence detected in AMG solver: pressure correction Error Object: ()" When I work with ideal gas there is no problem. But when I am to work with a fluid, such a problem occurs. Can anyone advice me anything with that? Thank you all. I am waiting from you.
I would like to have my model as the attachment. I found that 'layering' scheme might be useful for my case which might have similarity with your case. Can please lead me to have proper way in setting the 'layering' scheme of dynamic mesh? Thanks for your help. It is urgent to me. Please help.
Attached Images
 layering volume increment.jpg (89.7 KB, 16 views)

September 20, 2011, 17:34
#6
New Member

Daniel Jasiński
Join Date: Sep 2011
Posts: 2
Rep Power: 0
Quote:
 Originally Posted by coolengineer I think it is because of Continuity. When I use ideal gas as a fluid, Fluent goes on calculations without an error. However, when I chose a fluid, a kind of incompressible fluid, the continuity residual diverges. Would it be because of this?If so, how can I overcome this problem?
I know it's an old post but I have a question. What motion function do you use??
Do you use In-cylinder piston motion function??

 Tags dynamic mesh, layering

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