dolfin team mailing list archive

[Peter Brune <prbrune@xxxxxxxxx>]

As a quick solution, you could, knowing the coordinates of a node, constrain
everything within some epsilon smaller than the mesh feature size of the
node (such as DOLFIN_EPS).

- Peter

On Sat, Aug 8, 2009 at 11:27 PM, Catherine Micek <mice0012@xxxxxxx> wrote:

> 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
>
> ---
> Catherine (Katy) A. Micek
> Graduate Assistant, U of MN Mathematics Department
> http://www.math.umn.edu/~mice0012 <http://www.math.umn.edu/%7Emice0012>
>
>
>
>
>
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