Algebraic multigrid - AMG
Algebraic Multigrid (AMG)
This algorithm is referred to as an algebraic multigrid scheme because the coarse level equations are generated without the use of any geometry or re-discretization on the coarse levels. This has advantage that no coarse level grids have to be generated or stored, and no fluxes or source terms need be calculated on the coarse levels. This feature makes AMG particularly important for use on unstructured meshes. When using AMG, once the system is linearized, non-linearities are not "felt by the solver until the fine level operator is next updated.