Hi everybody,
I want to use fluid & shell interaction in COMSOL Multiphysics 5.4, so I'm trying to apply it on a simple geometry first, but I'm facing to an error any time: Failed to find consistent initial values. Also, I've tried to do this simulation in COMSOL Multiphysics 5.2, but I faced this error again.
I've searched for this error and tried the suggestions, but they didn't help me. It is noteworthy I've read this page:
https://www.comsol.com/forum/thread/25297/failed-to-find-consistent-initial-values
I attached two files (version 5.4 & 5.2). Can anyone explain to me what is the problem of the attached file? I've stuck in this problem for a very very long time.
I would be appreciated if anyone helped me possibly.
Dear Samin Haeri, the problem is not in the boundary conditions. you should check all of the initial conditions. the initial values like pressure, velocity and etc. check if they are a constant value or you are giving a function to them.
Hello Samin Haeri ,
Unfortunately I am not too familiar with fluid-structure interaction in COMSOL, hopefully somebody with experience will contribute soon.
However, I would suggest two things:
1) If you are able to provide some suitable non-zero initial conditions, this often aids the solver.
2) I have found that on occasions I have an ill-posed boundary condition and that I need to define it differently. I would highly recommend enabling 'Equation View' to see exactly what is being simulated. COMSOL also provide very comprehensive manuals for each module that often highlight any potential issues or considerations.
Thank you, Jules Lloyd Hammond ,
I've tried to use your first suggestion, but unfortunately, it didn't solve the problem.
Also, I checked the boundary conditions several times & I changed the boundary conditions, but unfortunately, it didn't solve the problem, too. I didn't recognize any ill-posed boundary condition.
Thank you so much for your response!
Dear Samin Haeri, the problem is not in the boundary conditions. you should check all of the initial conditions. the initial values like pressure, velocity and etc. check if they are a constant value or you are giving a function to them.
Thank you Reza Khazaee,
I've checked the initial conditions many times as it had been recommended in the attached link at the above. Also, I've changed the initial conditions & tried many different cases. But the error is still existing!
I can't find any mistake. I would be appreciated if you checked the file I've attached at the above if possible.
Dear Samin Haeri,
I agree with Jules Lloyd Hammond and @Reza Khazaee. The error is mainly caused by the initial conditions that are far from the final solution. This can be overcome in some cased by using a smoothed step input to avoid the sudden change in the solution (you can manipulate the time and observe the effect). In addition, there are some errors in the settings of the FSI and the materials (check all the settings). I fixed these issues and ran a single time-dependent study. You can modify the settings later.
Dear Marwan Nafea,
Thank you very very much! The FSI model (without applying prescribed displacement for a point) is simulated, finally!
But why it needs to add materials whereas I determined fluid properties & linear elastic material properties in FSI interface?
Dear Samin Haeri,
You are welcome. It is possible to include the properties of the materials in the FSI but you need to make sure that they are correct and used properly. I prefer to use materials from the library to avoid any issues even though you need to create or modify some materials based on your model.
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