Various techniques exist to either geometrically resolve or employ an appropriate body-force model for the representation of the propeller. The present research is devoted to the computation of geometrical resolved propeller flows in behind conditions.
The simulation of the hull-propeller interaction requires the coupling of a fixed grid around the hull with a moving grid attached to the rotating parts of the propulsive system. The coupling should ensure conservation of mass and momentum across the interfaces since, in the end, also pressure fluctuations with frequencies equal to a multiple of the blade frequency have to be transferred across the interface between the grids.
At present, sliding-interface methods are predominantly used for the propulsor analysis. When attention is directed to an assessment of more unconventional propulsors, e.g. cycloidal drives, the flexibility requirements on the meshing approach are significantly enhanced. In order to reduce the associated efforts without compromising the predictive accuracy and to maintain a fair comparability between different configurations during a concept study, overset techniques seem a promising approach. Another area, where overset meshes are beneficial is the simulation of propeller-hull-rudder interaction and related parameter studies, e.g. into the respective influence of the propeller-rudder clearance or the location of energy saving devices. The respective component meshes can be generated at moderate effort since no further geometrical restrictions need to be considered. Moreover, they can be re-used for the parameter studies.The abovely shown animation illustrates the results of such an approach.
A robust and accurate overset-mesh technology enhances the state-of-the-art possibilities of hydrodynamic simulation tools and might facilitate a significant speed up during the design and optimization cycle. These benefits are traded against an enhanced data-management effort and mass and momentum conservation challenges.
The project is funded by the EU Commission's Seventh Research Framework Program (Grant FP7-233896). The work is performed in colaboration with ARTITIC, Chalmers Univ., CNRS-Nantes, CTO, Entwicklungszentrum für Schiffstechnik und Transportsysteme, FOA, Hamburgische Schiffbau Versuchsanstalt, HRP-Thruster Systems, INSEAN, Lloýd's Register, MARIN, Rolls-Royce, Rolls-Royce Marine, Scitek Consultants, SSPA, Univ. Newcastle, STENA, Univ. Strathclide, Walvisstaart and Wilhelmsen Marine Consultants.