dolfin team mailing list archive

[Catherine Micek <mice0012@xxxxxxx>]

Hi,

I'm working with a group that's using Fenics to study the equations  
of linear elasticity (with a pure displacement formulation), and I  
have a question about boundary conditions.  Our goal is to study the  
pure traction problem, and this means we have to be careful in  
formulating the boundary conditions.  In order to prevent a  
singularity in our equations, we need to constrain certain nodes so  
as to prevent translations and rigid rotations.  There are many  
examples in the fenics demos about how to prescribe mixed conditions,  
but I have only seen examples where the Dirichlet condition occurs  
along an edge (as opposed to occurring at a few individual nodes).   
So my question is, given a mesh, how does one prescribe Dirichlet  
conditions for individual nodes?  Are there any demos that address this?

Any help would be greatly appreciated -- thanks!

Katy

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Catherine (Katy) A. Micek
Graduate Assistant, U of MN Mathematics Department
http://www.math.umn.edu/~mice0012