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Cauchy boundary conditions
Posted Dec 28, 2010, 1:25 a.m. EST 0 Replies
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I have a domain with a circular boundary. On this circular boundary, I want to implement Cauchy bcs - that is for a function u, I want to specify u and -n * grad(u) on the boundary. How exactly do I do this? In COMSOL, it seems that by choosing the Dirichlet bcs (from Physics -> Boundary settings --> etc.) we can almost do this because there are two equations to set: 1) R = 0 and 2) -n* (grad(u) +...) = G + dR/du^T * mu = 0. We can set R = u - c, to have u = c at the boundary. To set the normal derivative of u at the boundary, we can specify G appropriately, but then we have this Lagrange multiplier term. I want to get rid of this, that is to just have -n*grad(u) = G. How do I do this?
Thanks,
John Smith
Hello John Smith
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