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jadornonunez1-Visitor
1-Visitor
May 15, 2014
Solved

Neumann Boundary Conditions

  • May 15, 2014
  • 1 reply
  • 4375 views

Hello folks,

I'm trying to learn how to specify Neumann boundary conditions using numol to solve a PDE.

As you may be aware, Prime 3.0 does not feature Pdesolve so if we want to solve a PDE, we need to use either numol, relax or multigrid.

I'm using a rather simple example of Pdesolve in which we have a flat plate perfectly insulated at x=0 and with convection at x=L.

Now, the problem I'm having is that I cannot decipher how to express these boundaries conditions when using numol.

If someone knows how to do this, please solve the problem in the attached file using numol and post the solution in the reply.

Thanks a lot for you help!

P.S.: I saved the file in Mathcad 11 format so that a bigger audience may be able to open it and contribute. Thanks again.

Best answer by HarveyHensley

Try this. I did it in MC 15 so I could read your model easily but it should work the same in Prime.

1 reply

H
HarveyHensley12-Amethyst
12-Amethyst
May 15, 2014

I looked at your pdesolve example and your second boundary condition is called "mixed", not Neumann, because it involves both the dependent variable and its derivative. Numol does not accept mixed boundary conditions. That is why we need pdesolve back in Prime, but hopefully in a vector/matrix form.

J
jadornonunez1-VisitorAuthor
1-Visitor
May 15, 2014

Thanks Harvey for your reply.

Now, if we change the second boundary condition to a true Neumann BC, say, a heat flux of 5. How do we set up the boundary conditions?

The example that is included in the Mathcad 15 help is, in my opinion, confusing, at least in terms of the boundary conditions.

Thank you again.

H
HarveyHensley12-AmethystAnswer
12-Amethyst
May 16, 2014

Try this. I did it in MC 15 so I could read your model easily but it should work the same in Prime.

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