Abstract: The advection-diffusion equation is one of the important equations in oceanography that use in all hydro dynamical models. In this study ""Pure Advection"" equation that has been solved by several methods that accuracy of them was discussed. This article investigates a numerical scheme based on the high-order accurate method for solving diffusion equation. We discuss some finite difference techniques. We compare numerical and exact solution and we find our numerical scheme is effective for solving diffusion equation.
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