HOW TO RESOLVE THIS PROBLEM

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Author Message   gehong (gehong518) New member Username: gehong518 Post Number: 2 Registered: 12-2006 Posted on Tuesday, December 12, 2006 - 09:27 am:    my script Hello.doc (36.9 k) Hello, G. Nelson I am new to the software, and I have a trouble on boundary condition. I tried to solve a PDE problem in the attachment in a 2D-rectangular region.I have read most of the documentation and examples. However, I couldn't find the answer for, in provided documentation/help/examples. I hope I can get your help. Thanks!   Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 713 Registered: 06-2003 Posted on Wednesday, December 13, 2006 - 03:28 pm:    If you use the Vb=Vt condition as a Boundary condition on Vb, as you have indicated in your script (applied over the entire boundary), you still need to supply a BC for Vt. The Natural BC for Vt specifies (in your equation system) the outward normal derivative of Vt. (See Natural BC in the Help Index). From your equation (2), dn(Vt) = -[dsubt/d(x,y)]*dn(Vb) So the specification NATURAL(Vt) = -[dsubt/d(x,y)]*NORMAL(GRAD(Vb)) should do what you want.