[Getdp] Neummann boundary condition
Christophe.Geuzaine at ulg.ac.be
Fri Oct 26 11:22:19 CEST 2001
Lin Ji wrote:
> Hi, Christophe,
> I am still using getdp to solve 2-D accoustic wave equation in bounded
> half space with Neummann boundary condition on all four sides. Recently, I
> noticed that the way I specify the Neumman boundary condition in getdp should
> be examined more carefully. I know that when we write out the wave equation
> in weak form, the Neummann boundary function would appear in the equation as
> an integral with test function on the boundary. I thought it is equivalent to
> specifying Neumman boundary condition explicitly. But now, I doute it.
> I checked the reference. It seems to me there is no example for
> specifying such boundary condition in the Constaint object. The Assign type
> in the Constraint object seems only apply to Dirichlet boundary condition.
> So, can you let me know how to specify Neummann boundary condition explicitly
> in getdp in the way as specifying Dirichlet boundary condition? Thanks in
Neumann boundary conditions _are_ defined in a weak sense (through a
surface integral with test functions). There is no way to explicitely
fix beforehand the associated coefficients in a function space.
Tel: 32 (0) 4 366 37 10 http://geuz.org
Fax: 32 (0) 4 366 29 10 mailto:Christophe.Geuzaine at ulg.ac.be
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