ufl team mailing list archive

[Martin Sandve Alnæs <martinal@xxxxxxxxx>]

Yes.

grad(u).T*u
=
dot(grad(u).T, u)
=
dot(u, grad(u))

Martin



On Tue, Apr 7, 2009 at 6:40 PM, Anders Logg <logg@xxxxxxxxx> wrote:
> On Tue, Apr 07, 2009 at 05:19:42PM +0200, Martin Sandve Alnæs wrote:
>> On Tue, Apr 7, 2009 at 5:17 PM, Anders Logg <logg@xxxxxxxxx> wrote:
>> > On Tue, Apr 07, 2009 at 02:48:44PM +0200, UFL wrote:
>> >> One or more new changesets pushed to the primary ufl repository.
>> >> A short summary of the last three changesets is included below.
>> >>
>> >> changeset:   811:b96d2bbe8284a7255ca510c2fbb35b1445f85a11
>> >> tag:         tip
>> >> user:        "Martin Sandve Alnæs <martinal@xxxxxxxxx>"
>> >> date:        Tue Apr 07 14:50:30 2009 +0200
>> >> files:       doc/manual/chapters/formlanguage.tex ufl/operators.py
>> >> description:
>> >> Added support for this syntax:
>> >>
>> >> x = cell.x
>> >> Df = diff(f, x)
>> >>
>> >> Note that
>> >>   diff(f, x) == grad(f).T
>> >> because of the way diff is defined.
>> >> Thus diff(f,x) is the same as the FFC grad.
>> >> If we want to change this, it touches a lot
>> >> of places in AD code, so that won't happen now.
>> >
>> > How should the Navier-Stokes convective term be expressed in UFL?
>> >
>> > I guess one needs to write
>> >
>> >  grad(u).T*u
>> >
>> > ?
>>
>> Like you write it on paper:
>>
>> w . grad u = dot(w, grad(u))
>>
>> And:
>>
>> w . grad u . v = dot(dot(w, grad(u)), v)
>
> Yes, but does
>
>  grad(u).T*u
>
> also work?
>
> --
> Anders
>
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