Re: [Libmesh-devel] Issue with negative jacobian

[David K. <dav...@ak...>]

On Tue, May 5, 2015 at 10:10 AM, John Peterson <jwp...@gm...> wrote:

>
>
> On Tue, May 5, 2015 at 7:10 AM, David Knezevic <dav...@ak...
> > wrote:
>
>> I'm getting a negative jacobian error for a mesh created in CUBIT. CUBIT
>> says that the smallest jacobian in the mesh is around 1.e-4, but when I
>> load the mesh into libMesh and call fe->reinit(elem) on each element, I get
>> the error below.
>>
>> The mesh looks fine to me (it's 1.3MB so I can't attach it here, but I'd
>> be happy to email it to anyone who is interested). Does anyone have any
>> ideas why this might be happening?
>>
>
> What kind of elements?  If it's QUAD4s, maybe cubit measures Jacobians at
> the centroid of each element but then libmesh evaluates them at all the
> quadrature points, so the Jacobian goes slightly negative in parts of your
> 1.e-4 element?
>

They're TET10s. The elements should have affine mappings as far as I can
tell, so I would expect the Jacobian to be the same everywhere in the
element.

David