Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
Time stepping - level set method
Posted 1 févr. 2010, 03:58 UTC−5 2 Replies
Please login with a confirmed email address before reporting spam
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 2 févr. 2010, 12:04 UTC−5
Please login with a confirmed email address before reporting spam
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...?
Please login with a confirmed email address before reporting spam
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.