While creating models with CFD codes it is important to check
whether the solution is independent of the grid. One way to perform
this study is to increase the number of grids in the simulation
till that accuracy is reached. The solution from two models of different
grid densities is compared. One or several such comparisons
can be done to ensure grid independency. If the solutions of the
highest two grids densities are within a sufficiently small predetermined
tolerance, the original grid density is considered sufficiently
accurate for engineering purposes.