Simulation of Floating Objects in Free-Surface Flows

In this thesis a model for the simulation of floating objects on free surfaces is presented. Free surfaces arise at the transition between two fluids with a large density difference, e.g. between water and air. This effect is important for a lot of technical applications, such as metal foaming or molding. Fluid flows around obstacles or flows involving solid bodies is a phenomenon, of equally notable importance and has applications ranging from vehicle construction to particle technologies and material sciences. For the research in these areas, computational models are applied with increased popularity. In the field of computational fluid dynamics the lattice Boltzmann methods have been established, as a powerful way to deal with various problems, including the simulation of free surface flows. Approaches for the incorporation of rigid bodies into a lattice Boltzmann model has also been successfully realized in the past. This thesis proposes a model, which combines both ideas, to simulate objects exposed to a liquid flow with a free surface. In order to simulate the behaviour of the objects in the flow, the lattice Boltzmann model is coupled with a rigid body physics engine. An external force is incorporated into the model, to simulate systems under the influence of gravity. For the second phase, a gas of negligible influence on the flow is assumed, such that only the liquid phase needs to be simulated. The presented model has been tested and validated in terms of drag forces and buoyant forces on primitive rigid bodies and was successfully applied to selected problems, e.g. the propulsion of a paddle wheel and the floating of concave objects.