Abstract In this thesis the development and application of an overlapping grid technique for the numerical computation of viscous incompressible flows around moving bodies is presented. A fully-implicit second-order finite volume method is used to discretize and solve the unsteadyfluid-flow equations on unstructured grids composed of cells of arbitrary shape. The computational domain is covered by a number of grids which overlap with each other and can move relative to each other in an arbitrary fashion. For the treatment of grid movement, besides the standard method which is based on the arbitrary Lagrangian-Eulerian formulation of the governing equations, a novel method based on the solution of the governing equations in their Eulerian formulation was developed. Thus, instead the computation of grid fluxes, the grid motion is taken into account by appropriate approximation of the local time derivative in the unsteady term of the governing equations and by adding mass sources/sinks produced by moving walls in the near-wall region. The new method allows the change in grid topology and can be conveniently used with a re-meshing technique. A special implicit procedure for coupling of the solution on overlapping grids is developed.The interpolation equations used to compute the variable values at interpolation cells distributed along grid interfaces are involved in the global system of linearized equations that arise from discretization. Such a modified linear equation system is solved for the whole domain providing that the solution is obtained on all grids simultaneously. In this way a strong inter-grid coupling characterized by smooth and unique solution in the whole overlapping region and a good convergence rate is achieved. The mass conservation, which is violated by interpolation, is enforced by adjusting the interface mass fluxes. For a successful handling of body motion, the computational cells are allowed to be active or passive, depending on their position relative to the computational domain. The grid cells which are at the current time step outside the computational domain (e.g. covered by a body) are temporarily deactivated. These cells are reactivated when they reenter the computational domain. In this way a motion of grid components of arbitrary large scales can be achieved. The method developed in the present study was verified by applying it to some flows for which either the numerical solution or experimental data were known or the solution could be obtained using another numerical technique available in the commercial software. The accuracy of the method was assessed through the systematical grid refinement. The potential of the proposed overlapping grid method and its advantages over other available techniques for handling moving bodies was demonstrated on a number of flows which involve complex and large-scale body motion.weiterlesen