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Time stepping - level set method
Posted 01.02.2010, 03:58 GMT-5 2 Replies
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Hi everyone
I'm trying to simulate a biphasic flow with the level set method and I have an issue with time stepping.
When I set the times (Solver Parameter - General tab) to a great value for the step, the model seems to be ok and the calculation converges, but that means simulating too far regarding the characteristic time of the flow. When I have a smaller value, the calculation doesn't converge and I get :
"there are two void equations (empty rows in matrix) for the variable u". And the same for v"".
Where can I find a reference to understand these time stepping issues?
Thanks in advance.
Benjamin
I'm trying to simulate a biphasic flow with the level set method and I have an issue with time stepping.
When I set the times (Solver Parameter - General tab) to a great value for the step, the model seems to be ok and the calculation converges, but that means simulating too far regarding the characteristic time of the flow. When I have a smaller value, the calculation doesn't converge and I get :
"there are two void equations (empty rows in matrix) for the variable u". And the same for v"".
Where can I find a reference to understand these time stepping issues?
Thanks in advance.
Benjamin
2 Replies Last Post 02.02.2010, 12:04 GMT-5
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Posted:
1 decade ago
Hi Benjamin,
I think I get that problem if an equation basically reduces to 0=0. i.e.: if the coefficients of your derivatives become zero for some reason. In that case, I don't think the solver can say anything about u or v. Can you check them to see what happens? Maybe the time step that works is skipping over something...?
I think I get that problem if an equation basically reduces to 0=0. i.e.: if the coefficients of your derivatives become zero for some reason. In that case, I don't think the solver can say anything about u or v. Can you check them to see what happens? Maybe the time step that works is skipping over something...?
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Posted:
1 decade ago
Michael
My initial conditions were wrong. There was no way my model could work. I still don't understand how it could give something realistic for this big time step.
Tkank you for your help.
My initial conditions were wrong. There was no way my model could work. I still don't understand how it could give something realistic for this big time step.
Tkank you for your help.