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A simple question...

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How does one set up a system where the following types of simple 1-D problems can be solved?

1. u''(x) = f(x), u(a) = A, u(b) = B, a and b within the domain but not necessarily on the boundaries.

2. u''(x) = f(x), u(a) = A, u'(b) = B, a and b within the domain but not necessarily on the boundaries.

These are simple to do analytically, and to program in FD form.

For example, let u'' = 2, u(0) = 0, u'(0) = 0. This is an initial value problem in which the value or its derivative on the right boundary is unspecified. It has the solution u(x) = x^2.

How does one set this up in Comsol? If tried all the obvious approaches twiddling the boundary conditions in various ways but can't get the right answer.

Anyone know how to do this?

Thanks

0 Replies Last Post 13 févr. 2010, 04:26 UTC−5
COMSOL Moderator

Hello Davis Sentman

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