[dune-fem] Building stiffness matrix

[Dedner, Andreas]

Hi.
Are you starting from the dune-fem-school? If so then you can easily adapt
the poisson example (witch assembles the stiffness matrix for
-div Kgrad u + Mu
to only contain the mass part.
Best
Andreas
________________________________
From: dune-fem-bounces+a.s.dedner=warwick.ac.uk at dune-project.org [dune-fem-bounces+a.s.dedner=warwick.ac.uk at dune-project.org] on behalf of Mauro Pagani [account.facile at hotmail.it]
Sent: 06 November 2012 10:47
To: dune-fem at dune-project.org
Subject: [dune-fem] Building stiffness matrix


Hi,

I have a problem about solving the equation

________________________________________________________________________________________________________

ε*ε ∂tv + 4v(v*v-1) - 0.5*ε*ε div M [\mathbf{\nabla}] v= 0

________________________________________________________________________________________________________

I manage to arrive to modelize this with Euler method, ! but I don't understand how to calculate Stiffness Matrix
of the form:

Sij = \intK ((M [\mathbf{\nabla}] φj)[\mathbf{\nabla}]φi) dx

With K a right triangle (dimensions h x h) of the grid and M the coefficient of anisotropy (in more dimensions this become a diagonal square matrix).

I know that S is symmetric, but not diagonal: so to build it I need to have a node and all its neighbours...how could I implement this?

Thank you for your help,

Mauro Pagani



-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.dune-project.org/pipermail/dune-fem/attachments/20121106/903b6db9/attachment.htm>