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Problem with Fluid Structure Interaction Model
Posted Jan 13, 2010, 4:59 p.m. EST Fluid & Heat, Microfluidics 2 Replies
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Hi
I'm using the Fluid Structure Interaction (FSI) Model from Model Library>MEMS module>Microfluidics Models (the one with a vertical obstacle inside a flow channel). I'm trying to solve the same model with different material properties, but i'm getting an error.
From options>constants menu i'm keeping all the default property values except for "eta" (fluid viscosity). I'm changing it to 315 instead of 0.001. Keeping all other properties and parameters same, while solving it, i'm getting the following error:
Error: Time 0: Nonlinear solver interrupted since convergence rate above limit. Last time step is not converged.
I've checked the nonlinear settings under solver parameters>time stepping and unchecked the box for "use limit on convergence rate", but still the solution didn't work. This time i've got the following error:
Error: Time 0: Nonlinear solver did not converge
The modified "eta" value is much higher from the original and it is just because the fluid i want to use is very viscous.
Any idea how to avoid this problem? Any insight would be much appreciated.
Thanks for your time.
I'm using the Fluid Structure Interaction (FSI) Model from Model Library>MEMS module>Microfluidics Models (the one with a vertical obstacle inside a flow channel). I'm trying to solve the same model with different material properties, but i'm getting an error.
From options>constants menu i'm keeping all the default property values except for "eta" (fluid viscosity). I'm changing it to 315 instead of 0.001. Keeping all other properties and parameters same, while solving it, i'm getting the following error:
Error: Time 0: Nonlinear solver interrupted since convergence rate above limit. Last time step is not converged.
I've checked the nonlinear settings under solver parameters>time stepping and unchecked the box for "use limit on convergence rate", but still the solution didn't work. This time i've got the following error:
Error: Time 0: Nonlinear solver did not converge
The modified "eta" value is much higher from the original and it is just because the fluid i want to use is very viscous.
Any idea how to avoid this problem? Any insight would be much appreciated.
Thanks for your time.
2 Replies Last Post Jan 14, 2010, 12:17 a.m. EST
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Posted:
1 decade ago
Hi
Well I would find it rather normal, that changing the viscousity by almost 6 order of magnitude your solver needs some tweaking, is it glass flow you are simulating ;)
Unfortunately, I'm not the best to help for that, havnt been playing enough with exotic cases in the fluid dynamics. But I would start by reading over the solver settings guide. And a higher viousity means less far motion, hence a finer time step or equivalent.
I know there are a few fluid specialist on the forum,
Good luck
Ivar
Well I would find it rather normal, that changing the viscousity by almost 6 order of magnitude your solver needs some tweaking, is it glass flow you are simulating ;)
Unfortunately, I'm not the best to help for that, havnt been playing enough with exotic cases in the fluid dynamics. But I would start by reading over the solver settings guide. And a higher viousity means less far motion, hence a finer time step or equivalent.
I know there are a few fluid specialist on the forum,
Good luck
Ivar
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Posted:
1 decade ago
Thanks Ivar for your thoughts.
Yes, the viscosity change is too large and i don't know yet where exactly to tweak in the settings. I've already started reading the relevant documentation. Hopefully, someone with the fluid expertise would look into this in the mean time.
Trust me, there are polymers which are no softer than glass even at high temperature!
Regards.
Yes, the viscosity change is too large and i don't know yet where exactly to tweak in the settings. I've already started reading the relevant documentation. Hopefully, someone with the fluid expertise would look into this in the mean time.
Trust me, there are polymers which are no softer than glass even at high temperature!
Regards.