The process of converting governing partial differential equations into algebraic equation is known as discretisation. The finite difference method is one of the most powerful and simple method to convert partial differential equation (PDE) into algebraic equation. The accuracy of finite difference method increases with refining grid size. In this present study the finite difference method (FDM) is used to determine the shear stress over a flat plate. This shear stress is function of velocity gradient as given by Newton's Law of viscosity. The first derivative of velocity gradient is replaced by forward difference, Reward difference and the central difference approaches. The exact solution of equation is compared with approximate solution and the errors are determined for different values of grid points spacing. It is found that central approach is more accurate than forward and reward approaches. The effect of order of accuracy such as O(Δy), O(Δy)2, O(Δy)3 has been also studied. It shows as order of accuracy increases, computational errors decreases.
Discretisation, PDE, Finite difference method, Forward difference, Reward difference, Central difference, Order of accuracy, Mesh spacing
