Learning Forum

[Ahmed_Aissa]

Dear all,

I am simulating a valve cycle (opening/ closing) FSI problem using system-coupling GUI. I am using IQN-ILS to try stabilizing the solution. IQN-ILS seems to not allow restarting as information from previous time-steps is eventually lost. Thus, I need to figure out a method to overcome this issue.

1- Porous zone (Expression to vary the permeability and mimic close and open channel) : Not working/ System Coupling does not support porous zone (I am not interested in porous jump though)

2- The wall boundary condition seems to do the job for me: I can start from a closed valve, run during a certain flow time but then I want to open the valve by removing the wall. So I am using an event for that because restarting QN-ILS significantly deteriorates the convergence of my results (So stop and restart the analysis is not on the table)

3- Deactivating and activating cell zone is also a good option ( I would say a better option than the wall boundary because it removes unwanted boundaries and brings them back to the analysis when reactivated)

Dynamic mesh event works perfectly fine using Fluent standalone solver. However, Systemcoupling does not progress anymore using the events (Wall/interior or activating/deactivating cell zones). Mainly, Fluent gets stuck during a coupled run, but with no progress and no error.

Is it a compatibility issue? Or it has something to do with the setting I am using?

Can you confirm that Quasi-Newton cannot be restarted? from the documentation, I see that you need the maximum number of iteration must be equal to 1, I did not understand why.

NB: I am running a 3D case in parallel.

Thank you for your help.

Ahmed,

[Rob]

Why do you want to use system coupling? Is the valve deforming because of the flow?

[Ahmed_Aissa]

The valve is made from a hyperelastic material. The deformation is highly non-linear and needs to be stabilized using the appropriate technique.
I am not sure if a high nonlinear deformation can be modled using UDF

[Rob]

It probably can, but I'd get someone to use Mechanical for that part. can advise.