dolfin team mailing list archive

[jhoffman@xxxxxxxxxxx]

Garth,

I have added the SUP-stabilized module. It compiles, but I have not yet
tried it in a solver.

/Johan

> On Tue, Jul 12, 2005 at 06:49:40PM +0200, Garth N. Wells wrote:
>> Attached are files for SUPG stabilised convection-diffusion. They
>> simply replace existing files in src/modules/convdiff and
>> src/modules/convdiff/dolfin.
>
> Great! I've been waiting for someone to come along and stabilize the
> convection-diffusion module.
>
> I'll add this, but probably not today (and perhaps not until after my
> vacation).
>
>> The stabilisation terms are computed in a very simple
>> fashion. Things could be made simpler if it were possible to perform
>> more algebraic operations on functions with ffc such as taking
>> square roots, inverses, etc. Would this be possible Anders?
>
> Yes, I think it's possible to extend the capabilities of FFC to handle
> almost any kind of operations applied to Function (but not to
> BasisFunction). This can be done by replacing each operation
>
>     op
>
> with
>
>     pi op pi
>
> where pi is a projection or interpolant onto the finite element space.
>
> In the simplest case, pi is just nodal interpolation and op is defined
> point-wise, so if w is a given function, then
>
>     op w --> pi op pi w = pi op sum_i w_i phi_i
>                         = sum_i op(w_i) phi_i
>
> In the case of the square-root, we would just take the square-roots of
> the expansion coefficients and this might as well be done by FFC as by
> DOLFIN. (FFC would generate a couple of extra lines of code for doing
> the operations on the expansion coefficients.)
>
> I'll add this to my TODO list.
>
> /Anders
>
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