School of Mathematics and Statistics, Chongqing Three Gorges University, Chongqing 404000, P.R.China
In this paper, a positive definite semi-discrete mixed finite element method was presented for two-dimensional parabolic equations. In the new positive definite systems, the gradient equation and flux equations were separated from their scalar unknown equations. Also, the existence and uniqueness of the semi-discrete mixed finite element solutions were proven. Error estimates were also obtained for the semi-discrete schemes.Finally, a numerical example was presented to show theoretical results.