See also MARIN YouTube channel for the latest ReFRESCO CFD simulation movies.
Figure 1: Streamline tanker geometry and grid layout
interfaces and parallelisation of the algo- rithms have been addressed.
For tackling the propulsion system problem MARIN can now fully simulate the translating ship+rudder system together with the rotating propeller, (see Figure 1), in one un- steady viscous-flow RANS calculation. The calculation costs increase significantly: from hours with a RANS-BEM approach to days for a full RANS approach in a modern HPC cluster. Nevertheless, the amount of infor- mation and correct interaction effects that can be simulated are also considerable. Figure 2 shows the flow (velocity, pressure field and limiting streamlines) around the stern and close aft of the propeller before the rudder location. The influence of the propeller load on the hull flow and of the propeller slipstream on the rudder flow (and the opposite effects) are captured here without simplifications. The analysis of these complex phenomena is now possible.
New possibilities The new ReFRESCO Code makes the unified simulation of trans- lating and/or rotating systems in one grid/ calculation possible. This is relevant not only for the propulsion system situation illustrated here but also for thrusters and DP systems, roll-damping simulations, offshore
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VIV/VIM problems, manoeuvring ships, passing ships, active rudders and fins etc. In the near future MARIN envisages self-propulsion numerical tests for ship propulsion using ReFRESCO.
1. D. Rijpkema and G. Vaz, “Viscous Flow Computations on Propulsors: Verification, Validation and Scale Effects”. In Proceedings of RINA-CFD2011, London, UK, March 2011.
Figure 2: (left) Pressure field and limiting streamlines at stern region. (right) Axial and tangential velocity field at a station between the propeller and rudder.
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