Fig. 8

Typical 2D isotropic grids. a Regular quadrilateral grids. b Regular triangular grids. c Skewed quadrilateral grids. d Skewed regular triangular grids. e Perturbed quadrilateral grids. f Random triangular grids. g Regular double-split triangular grids. h Isotropic quadrilateral grids on curved surface. i Isotropic regular triangular grids on curved surface