ABSTRACT
The starting point of any numerical method is the mathematical model, the set of partial differential equations and boundary conditions. After selecting the mathematical model, one has to choose a suitable discretization method. The most important are: finite differences (FD), finite volume (FV) and finite element (FE) methods. The discrete locations at which the variables are to be calculated are defined by the numerical grid, which is essentially a discrete representation of the geometric domain on which the problem is to be solved. It divides the solution domain into a finite number of sub domains. Different types of grids are:
• Structured grid: A structured mesh is defined as a mesh where all the nodes have the same number of elements around it. This makes that the matrix of algebraic equation system has a regular structure. There is large number of efficient solvers applicable only to structured grids. Disadvantages are only for geometrically simple domains.
