TABLE OF CONTENTS We have now reached the stage where you can start applying the acquired methodology to compute realistic flows.
You certainly have gained the awareness from the previous chapters, that for any mathematical model an unlimited number of options are available to set up the numerical model, although practical experience reduces the choice to a more restricted range. In the previous chapters, we have focused essentially on numerical schemes of second order accuracy in space, which is generally considered as providing the best compromise in terms of cost to accuracy ratio. This still leaves many options open, as different schemes have different dissipation and dispersion error properties.
Writing CFD codes is a learning process where many components have to be taken into account, step by step. Whatever mathematical model you select, from the simplest potential flow to Euler equations, up to laminar and turbulent full Navier-Stokes models, you have to make a choice on each of the following topics and to evaluate their impact on the solution accuracy, on convergence behavior and on computational time:
The type of grid and its mesh point density, cell-centered or cell-vertex configurations.
The numerical scheme, defined by the selected time and space discretization. For steady state simulations, you need to select only the space discretization.
The boundary conditions and their numerical implementation.
The resolution method of the obtained algebraic system and the treatment of the nonlinearities.
