dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Mon, Apr 23, 2007 at 11:31:40PM +0200, Garth N. Wells wrote:

> Anders Logg wrote:
> > On Mon, Apr 23, 2007 at 06:50:17PM +0200, Garth N. Wells wrote:
> >> Quoting Anders Logg <logg@xxxxxxxxx>:
> >>
> >>> On Mon, Apr 23, 2007 at 07:04:16PM +0200, DOLFIN wrote:
> >>>> One or more new changesets pushed to the primary DOLFIN repository.
> >>>> A short summary of the last three changesets is included below.
> >>>>
> >>>> changeset:   2900:cc8dbffbcc9cebe6761eceb5b91d324e0ec2caf0
> >>>> tag:         tip
> >>>> user:        "Garth N. Wells <g.n.wells@xxxxxxxxxx>"
> >>>> date:        Mon Apr 23 19:04:03 2007 +0200
> >>>> files:       src/kernel/io/VTKFile.cpp
> >>>> description:
> >>>> Fix VTK outout. Results look ok now.
> >>> Very nice. Maybe we should put back the same boundary condition as we
> >>> had before and compare the results (the solution vector number by
> >>> number) with the old demo. That would be a very good indicator that
> >>> we are on the right track.
> >>>
> >> Do we still need to do some work on applying Dirichlet boundary conditions to
> >> particular components of a vector only, or is this already implemented?
> >>
> >> Garth
> > 
> > I think this is not needed for the elasticity demo since we set the
> > values for all the vector components. The displacement is u = [0, 0, 0]
> > at one end and u = [ux, uy, uz] at the other end.
> >
> 
> Looks like the boundary condition at one end is u = [-, uy, uz].

ok, I see that now. It's sort of a strange boundary condition. You
twist the gear around the x-axis but allow it to slide in the
x-direction.

> I've applied the same boundary conditions for the new and the old
> code, 

Setting ux to 0 in both?

> and the results are close, but not the same. One issue is that FFC is 
> producing code with fewer significant digits than previously.

How close?

Kristian and I reduced the number of significant digits to get
reproducible results when running the regression test in FFC. (The
last digits may otherwise differ between different machines, Python
versions, time of day, weather conditions etc.)

/Anders


> Garth
> 
> > This problem does not show up until we get to the Stokes demo.
> > 
> > /Anders
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> > 
> 
> 
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