understanding Devices


Figure 3


very accurate. To obtain accurate results, a fully verified and validated CFD code for ship and propeller flows, such as ReFRESCO [1], is a must.


Even with an accurate CFD code, achieving good quality results is challenging because the complex interactions between the propeller, hull and ESD make the CFD simu- lations extremely intricate. The geometries are complicated and care has to be taken when making simplifications and the quality of a computational grid has an important influence on the accuracy of a CFD calcula- tion. Recent developments at MARIN facilitate the generation of high quality structured grids for propellers, without making conces- sions to the propeller geometry, see Figure 2. This results in a better iterative convergence and improves the accuracy of the calculation. Additionally, time-consuming unsteady calculations are needed to capture all inter- action effects. This is only possible with the combined use of our in-house CFD code ReFRESCO (requiring no licence fee) and our HPC clusters (maximum of 2,000 cores).


Current and future Work MARIN participates in the European Union project Green Retrofitting through Improved Propul- sion (GRIP). One of the main pillars of the project is to identify working principles of ESDs. Once working principles have been identified, new concept designs can be made, for example the BSD concept design presented in Figure 3 and [2]. MARIN will continue to study and design ESDs in order to fully understand their underlying princi- ples to enable it to give independent advice to clients on ESD performance predictions. In terms of CFD, accuracy (by decreasing the numerical uncertainties and by using finer turbulence models) and performance (by decreasing computational times) are the major areas of focus for the coming years.


Figure 1. Illustrative example presenting the possibilities with CFD analysis


Figure 2. Perspective view on an unstructured computational grid for a ship with ESD and a structured propeller grid


Figure 3. The ESD concept design called the BSD


1. RIJPKEMA, D. and VAZ, G., “Viscous Flow Computations on Propulsors: Verification, Validation and Scale Effects”, In Proc. of Developments in Marine CFD, London, UK, March 2011.


2. SCHUILING, B. “The Design and Numerical Demonstration of a New Energy Saving Device”, NUTTS, September 2013.


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