On Mon, Sep 24, 2018 at 11:12 AM Amneet Bhalla <mail2amn...@gmail.com> wrote:
> Hi John, > > Is there a way to obtain phi values at the centroid of the element (or in > general any other point inside the element)? We can potentially interpolate > nodal normals to centroid normal. > QGauss at CONSTANT/FIRST order will give you a quadrature rule with one point at the element centroid. If you want values at an arbitrary point in the element, you can call the FE::reinit() overload that takes pointers to vectors of points and weights defining a "custom" quadrature rule. > > PPS: Just checking QTRAP is exact for FIRST order elements, and QSIMPSON is > exact for SECOND order elements in libMesh. > Depends what you mean by "exact". QTrap/QSimpson will give you nodal quadrature rules for FIRST and SECOND order elements, respectively. On a per-node basis these rules are not as accurate as the corresponding Gauss rules. For example, a 2x2 Gaussian quadrature rule can integrate a bi-cubic function exactly, whereas the 2x2 QTrap rule should only be able to integrate a bilinear function exactly IIRC. -- John _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
