Using orthogonality properties

1. Dec 18, 2009

jgthb

Hello

I have been wondering for some time about, why I have to use orthogonality properties in a special kind of PDE problem I have encountered a few times now.

As an example see exercise 13-3 in this file:
http://www.student.dtu.dk/~s072258/01246-2009-week13.pdf" [Broken]

I have described my thoughts on this in this file:

And I have solved the problem in this file (the right way by use of orthogonality properties):
http://www.student.dtu.dk/~s072258/orthogonality_solution.pdf" [Broken]

The last file is in danish, but part b) (which I comment on in the second file) almost only consist of calculations, so it shouldn't be a problem.

Some insight would be much appreciated :)
Jonathan

Last edited by a moderator: May 4, 2017
2. Dec 20, 2009

jgthb

Last edited by a moderator: Apr 24, 2017