Dear Nicolas, The serendipity family is called “S” in Firedrake, so the following code would create a Serendipity 2 function space on a unit square: In [1]: from firedrake import * In [2]: mesh = UnitSquareMesh(10, 10, quadrilateral=True) In [3]: fs = FunctionSpace(mesh, "S", 2) You could also create a quad mesh in, for example, gmsh and read it in. For the 3D case you would need to extrude a quad mesh, and the rest follows. Regards, DAvid From: <firedrake-bounces@imperial.ac.uk> on behalf of Karin&NiKo <niko.karin@gmail.com> Date: Friday, 24 January 2020 at 14:49 To: firedrake <firedrake@imperial.ac.uk> Subject: [firedrake] Serendipity elements Dear Firedrakers, I would like to use continuous finite elements from the serendipity family. At the moment, I would like to use some simple quadratic 8-nodes quadrangles and 20-nodes hexaedra (the S2 element from the “Periodic table of the finite elements”). I do not find any tests in Firedrake src (grep -ri functionspace * | grep \"S). How can I do to use these finite elements? Thanks, Nicolas