The equation of the curved edge for isoparametric cubic finite elements

Optimal Subparametric Finite Elements for Elliptic Partial Differential Equations Using Higher-Order Curved Triangular Elements

“…This will reduce the computational cost resulting from the evaluation of the finite element matrices. Third, the distribution of the nodal points inside each curved elements ensures the objectivity of the mapping, which leads to optimal convergence rates of the FEM; see Kesavulu, Naidu, and Nagaraja [14], Rathod et al [6], Woodford et al [15], Woodford [16], Mitchell and Wachspress [17], Lenoir [18], and Fahs [19].…”