Multiblock

The multiblock strategy for the LBM grid allows the existence of several refinement levels in the domain. The coarsest level is \(n=0\) and the finest level is \(n=N\), where \(N\) is the maximum level. The elementary volume consists of a cube of an integer size \(d\), called block. Every block in the domain, regardless of its refinement level, contains the same number of LBM nodes. When a block is refined, it subdivides in 8 cubes of size \(d/2\), see figure below:

Neighboring blocks of size \(d=4\) are illustrated in the figure below:

LBM nodes are shown in the frontal face. In the cell-vertex approach, each face of a block has \((d)^2\) nodes.

Note

One important aspect of this approach is the recursiveness. So the same rules and properties applies when dividing a block from level 0 to 1 or 1 to 2, and so on. This allows the application of same communication rules, for example, for every level transition.