Numerical simulations of coupled fluid-rigid solid problems by multigrid
fictitious boundary and grid deformation methods are presented. The flow is computed
by a special ALE formulation with a multigrid finite element solver. The solid
body is allowed to move freely through the computational mesh which is adaptively
aligned by a special mesh deformation method such that the accuracy for dealing
with the interaction between the fluid and the solid body is highly improved.
Numerical examples are provided to show the efficiency of the presented method.