Rectilinear grid

A regular grid is a tessellation of n-dimensional Euclidean space by congruent parallelotopes (e.g. bricks). Grids of this type appear on graph paper and may be used in finite element analysis as well as finite volume methods and finite difference methods. Since the derivatives of field variables can be conveniently expressed as finite differences, structured grids mainly appear in finite difference methods. Unstructured grids offer more flexibility than structured grids and hence are very useful in finite element and finite volume methods.

Each cell in the grid can be addressed by index (i, j) in two dimensions or (i, j, k) in three dimensions, and each vertex has coordinates ${\displaystyle (i\cdot dx,j\cdot dy)}$ in 2D or ${\displaystyle (i\cdot dx,j\cdot dy,k\cdot dz)}$ in 3D for some real numbers dx, dy, and dz representing the grid spacing.

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