Calculated wave pattern for a ferry

Potsdam Model Basin delivers the powerful in-house software KELVIN for the calculation of the ship wave resistance. This program combines a modern CFD code with an efficient CAD system using an IGES-interface. The implemented 3D-Viewer allows the 3-dimensional visualisation of results and the interactive generation of the numerical  grid on the ship hull. The program has been successfully applied to a very large number of ship design and analysis projects performed at the Potsdam Model Basin. Benefits in ship design are:

- Shortening development time
- CAD - linkable (standard IGES interface)
- Cheaper than model tests
- Understanding the details of the complex flow
- Easy handling

The potential flow calculation code is based on the advanced patch method developed by Prof. Söding (Fluid Dynamics and Ship Theory, Technische Universität Hamburg-Harburg). The code can be used for calculation of the wave resistance, wave pattern, pressure distribution on the hull, sinkage and trim of the ship at a constant speed. The code is able to handle a large number of different cases:

- unconfined, deep water condition
- mono- and multihull forms (catamarans, SWATH, trimarans, pentamarans)
- transom or tunnelled stern
- asymmetric ships
- shallow water
- fixed or free floating condition
- canal flows
- semi-submerged bow bulbs
- fully submerged fins

The code can handle any abrupt change of the underwater ship hull that is due to variations of the actual water line or the trim and the sinkage conditions during the computation. The wave resistance is calculated  by wave pattern analysis rather than from pressure integration.

Comparison of the calculated total resistance Rt = Rw+(1+k)*Rf and the resistance from the model test of a container ship; k according to ITTC78; frictional resistance Rf according to ITTC57.

 The viscous resistance is approximated by the formula based on the ITTC 57 friction line. The sum of wave and viscous resistance is given as the total resistance. The results can be visualised using the 3D-Viewer.

Calculated pressure distribution for a ferry.

Form optimisation

This tool supports the optimisation of a ship hull with regard to the resistance. The change of the ship resistance resulting from small  changes of the ship form is calculated.For this, locally limited deformations are applied to the grid by displacement of single grid points. The computed results show at which places of the ship surface the deformations cause a reduction in resistance. The tool can also be used to estimate the effect of possible hull form alterations  without  significant increase of the resistance.