===affil2: Lawrence Technological University ===firstname: Christopher ===firstname4: Jun ===firstname3: Ruxin ===lastname2: Wang ===lastname: Kawatsu ===firstname5: ===affil6: ===lastname3: Dai ===email: ckawatsu@ltu.edu ===lastname6: ===affil5: ===otherauths: ===lastname4: Zhang ===affil4: University of Kentucky ===lastname7: ===affil7: ===firstname7: ===postal: Department of Mathematics and Computer Science, Lawrence Technological University, 21000 West Ten Mile Road, Southfield, MI, 48075-1058 ===firstname6: ===ABSTRACT: A geometric multigrid method for solving the convection diffusion equation with boundary layers to sixth order accuracy is presented. A nine point finite difference discretization scheme is used to obtain fourth order accurate solutions on a coarse and a fine grid. Richardson extrapolation is used to increase the order of accuracy to sixth order on the coarse. An iterative smoothing technique is then used to obtain a sixth order solution on the fine grid. The discretization we used allows the grid to be a graded mesh. This is the first time the post extrapolation smoothing technique has been applied to a graded mesh. Numerical results are presented to demonstrate the use of a graded mesh can significantly decrease the maximum error compared to a regular mesh. ===affil3: University of Kentucky ===lastname5: ===affilother: ===title: A Sixth Order Compact Multigrid Solver for the Convection Diffusion Equation with Boundary Layers ===firstname2: Yin