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Jiexian Wu (jiexian_wu)
New member
Username: jiexian_wu

Post Number: 1
Registered: 08-2005
Posted on Thursday, August 18, 2005 - 04:04 am:   

Hello everyone. I have three nonlinear coupled equations with variables v1,v2,v3 in my problem. And I need to lock the value of varible v1 in one of my regions(not just the boundary) . I think I can't extrude this region ,because I need v2 and v3 to be computed in it .Can I do it in the FlexPDE ? And how ?
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Robert G. Nelson (rgnelson)
Moderator
Username: rgnelson

Post Number: 430
Registered: 06-2003
Posted on Thursday, August 18, 2005 - 02:22 pm:   

1.
If the initial value is set to the lock value, and if the region is surrounded by boundary conditions at the lock value, it should stay at that value throughout the run.

2.
Given situation 1, you could add a source/sink term in the locked region to prevent deviation from the lock value:
(original terms) + Large*(Vlock-V1) +...
Set Large = 0 in non-locked regions.
Choose the sign of Large to drive the value in the right direction.
Don't make Large too large, or it will swamp the numerics.
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Jiexian Wu (jiexian_wu)
New member
Username: jiexian_wu

Post Number: 2
Registered: 08-2005
Posted on Thursday, August 18, 2005 - 09:29 pm:   

Thank you very much ! Your explanations and suggestions are extremely useful for me .

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