Dave May <dave.mayhe...@gmail.com> writes: > On Thu 12. Jan 2023 at 17:58, Blaise Bourdin <bour...@mcmaster.ca> wrote: > >> Out of curiosity, what is the rationale for _reading_ high order gmsh >> meshes? >> > > GMSH can use a CAD engine like OpenCascade. This provides geometric > representations via things like BSplines. Such geometric representation are > not exposed to the users application code, nor are they embedded in any > mesh format GMSH emits. The next best thing is to use a high order > representation of the mesh geometry and project the CAD geometry (say a > BSpline) into this higher order function space. The projection of the > geometry is a quantity that can be described with the .msh format.
Adding to this, efficient methods for volumes with concave surfaces *must* use at least quadratic geometry. See Figure 5, where "p-refinement with linear geometry" causes anti-convergence (due the spurious stress singularities from the linear geometry, visible in Figure 4) while p-refinement with quadratic geometry is vastly more efficient despite the physical stress singularities that prevent exponential convergence. https://arxiv.org/pdf/2204.01722.pdf
