A Triangular Prism Finite Element For The Mixed Second-order Elliptic Problem

There are many researches for the finite element methods solving the two-order mixed elliptic problem, including triangular, rectangular, tetrahedral and cubic elements. How-ever there are little researches for triangular prism element. The triangular prism element than both of the triangular and rectangular elements are more convenient for column area, especially with complex cross-section. In this paper a low-order conforming tri-angular prism element is constructed for the the two-order mixed elliptic problem, its well-posedness and convergence are proven, and the optimal error estimates are given.