“…To overcome this limitation, in the last years there has been a great interest in developing FEMs that can employ general polygons and polyhedra as grid elements for the numerical discretizations of partial differential equations. We mention the mimetic finite difference method [1,2,3,4], the hybridizable discontinuous Galerkin method [5,6,7,8], the Polyhedral Discontinuous Galerkin (PolyDG) method [9,10,11,12,13,14,15], the Virtual Element Method (VEM) [16,17,18,19,20,21] and the Hybrid High-Order method [22,23,24,25,26]. This calls for the need to develop effective algorithms to handle polygonal and polyhedral grids and to assess their quality (see e.g.…”