S.O.S - Save our shores

June 2, 2000

Scientists at the University of Berlin chose the leading European Computational Fluid Dynamics (CFD) software system, STAR-CD from Computational Dynamics Ltd (CD), for computer simulation of Artificial Reefs Artificial reefs are environmentally friendly structures which serve to reduce wave transmission and reflection before waves break along the shore. Because of their high efficiency, well designed reefs can be very close to the shoreline so shipping channels are not adversely affected.

Typically they comprise three barely submerged porous filter banks oriented parallel to each other and perpendicular to the prevailing wave motion. The processes that lead to dissipation of the wave energy by such systems are complex, but can be understood from the computer simulations. The parameters optimised baffle were the porosity, height, number and separation, and the wave height and period. The model included free surface analysis, using the volume of fluid (VOF) method. The hydrodynamics of the calculation was complicated and non-linear, with separation and re-circulation occurring due to sloshing of water over the top of each filter bank. The results were interesting!

The STAR-CD simulations revealed that re-circulation of the flow trapped between filters made a substantial contribution to wave energy dissipation. Jet flow between filter components also helped energy loss. CD's Business Development Manager, Dr Michael Dickens says "CFD is the most rapidly growing CAE analysis tool, and here is an example of how new applications arise.

A few years ago CFD codes such as STAR-CD were used mainly in sophisticated manufacturing industries such as Automotive and Aerospace. However, now there is rapid growth of CFD to be found in Power, Chemical Process and, as here, new environmental applications. What is happening is that CFD codes are acting as a carrier of technology between industries. This is what is driving the growth of CFD and why our industry is such an exciting area to be in."

For information on the work at the Institute of Navel Architecture and Ocean Engineering of Berlin University of Technology, see www.ism.tu-berlin.de/MT/.