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maria hofer (maria)
New member
Username: maria

Post Number: 1
Registered: 11-2009
Posted on Wednesday, November 25, 2009 - 02:53 pm:   

Hello to the FlexPDE team,

I try to model the diffusion of a substance that is constantly added in a specified region of the problem domain (e.g. the constant flow of pollutants into a lake). I'm not sure if I get the idea of doing that in FlexPDE correctly.

So far I tried setting the value of the parameter "Q" (the source term) in the source region. Does this model the constant addition of the substance? Or is it a "one-time" addition of the specified value?

I also tried setting a VALUE boundary condition in the region representing the source. The result seems ok; but in this case I don't have the source term "Q" in my equation anymore, which changes the given description of the problem.

Any hints?
Thanks a lot in advance,
Maria




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Marek Nelson (mgnelson)
Moderator
Username: mgnelson

Post Number: 162
Registered: 07-2007
Posted on Friday, November 27, 2009 - 02:45 pm:   

In the diffusion equation DIV(K*GRAD(U))+Q = DT(U), Q is a source per unit volume per unit time.

A VALUE boundary condition sets the value of a variable at that boundary. If you use it, you should be sure that this correctly describes the system you want to solve.

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