dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Mon, Oct 19, 2009 at 12:40:49PM +0100, Garth N. Wells wrote:
>
>
> Anders Logg wrote:
> >On Mon, Oct 19, 2009 at 12:40:25PM +0900, azumi.hayakawa@xxxxxxxxxxxxxxxxxxx wrote:
> >>Hello.
> >>
> >>I want to implement a bilinear form for axisymmetric
> >>elastic problems on cylindrical coordinates (r, theta, z).
> >>All of displacement, strain, and stress are assumed
> >>to be axisymmetric.  I am expecting the form will look
> >>like:
> >>  def epsilon(v):
> >>    return
> >>      [ del(v.r)/del(r)         0      ]
> >>      [        0        del(v.z)/del(z)]
> >>      [ del(v.r)/del(z) del(v.z)/del(z)]
> >>      [      v.r/r              0      ]
> >
> >Try this:
> >
> >   def epsilon(v):
> >     return as_matrix([[del(v.r)/del(r), 0],
> >                      [0, del(v.z)/del(z)],
> >                      [del(v.r)/del(z), del(v.z)/del(z)],
> >                      [v.r/r, 0]])
> >
> >   def sigma(v):
> >     return E/((1+nu)*(1-2*nu))*as_matrix([[1-nu, nu, 0, nu ],
> >                                          [nu, 1-nu, 0, nu ],
> >                                          [0, 0, (1-2*nu)/2, 0],
> >                                          [nu, nu, 0, 1-nu]]) * epsilon(v)
> >
>
> Are r and z functions?
>
> I guess FFC will soon support using coordinates in a .ufl file.

There is already a Function named MeshCoordinates defined in
SpecialFunctions.h.

Perhaps we could just predefined x, y, z as being components of this
Function in PyDOLFIN?

--
Anders

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