A two-grid method for solving the Cahn-Hilliard equation is proposed in this paper.This two-grid method consists of two steps.First,solve the Cahn-Hilliard equation with an implicit mixed finite element method on a coarse grid.Second,solve two Poisson equations using multigrid methods on a fine grid.This two-grid method can also be combined with local mesh refinement to further improve the efficiency.Numerical results including two and three dimensional cases with linear or quadratic elements show that this two-grid method can speed up the existing mixed finite method while keeping the same convergence rate.
