On Wed, Jan 13, 2016 at 3:23 PM, Junchao Zhang <junchao.zh...@gmail.com> wrote:
> Hello, > I tried to follow the textbook to write weak forms of PDEs with Dirichlet > boundary conditions like some libmesh examples. The textbook usually lets u > = 0 on boundary, making it easy to understand why the boundary term > vanishes in weak form. But when u is not zero on boundary, I found libmesh > examples still do not have boundary terms in weak form. Why? > Not sure if this will help, but you can think of the basis functions associated with the Dirichlet BC degrees of freedom (DOFs) as being "thrown out" of the test space, i.e. we are not testing against them any more. You therefore have to replace the equations that would normally be associated with those DOFs with some other equations, e.g. penalty terms, constraints, etc. You have to do this regardless of whether the Dirichlet value is zero or not. -- John ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=267308311&iu=/4140 _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
