After reading the thread commenced by Chris Cochran on foils, I thought it would be a good time to let your readers know about a new research project that we have started at the University of Wales Swansea (United Kingdom). (By the way I would just like to commend the work done by Michael Paler in maintaining this forum, which is absolutely superb).
The project funding has been derived from previous work in aerospace engineering and consists of a panel of engineers supervising a three-year PhD position taken on by a computer scientist. The project intends to look at various aspects of the hydrodynamics of surfboards for differing board and fin designs, using 3D Computational Fluid Dynamics (CFD) and stress analysis modelling coupled with experimental validation and some new prototype designs for both boards and fins.
As mentioned by Simonc in a previous thread, “surfboards are extreme craft in hydro/fluid dynamic terms, exceptionally high Froude numbers and very low Reynolds numbers”. This presents many challenges in modelling the highly complex flow, (E.g. 3D complex geometry, Turbulence, Two-phase flow with solid interaction and sometimes deformation, plus free surface effects).
Surfboard design is at a critical stage in which it would greatly benefit from the type of computational modelling previously only associated with more lucrative industries such as hull design in yachts and powerboats, not to mention aerodynamic design in the aerospace and automotive industries. The application of CFD to sport is very topical, in particular in attempting to improve performance of sports equipment and technique enhancement, with articles in the spring issue of FLUENT news (2004) and the Journal of Sports Science, case studying research into advanced swimwear (sponsored by Speedo) for the Athens Olympics.
Due to the complexity of the flow, we have decided to validate our computational models experimentally using two sets of experimental rigs, one of which is nearing completion as I write this. This particular rig has been developed to fix fins into a flow tank allowing pressure distributions, drag forces and velocity boundary layers to be measured. The work will involve testing a number of existing fin designs as well as a number of new prototypes. Benchmark objects will also be placed in the rig to get free surface distributions for verification of “simple” modelling test cases.
The second set of experiments will use of a larger tow-tank with higher speeds to tow scaled models of surfboards with fins and will allow verification of free-surface heights of bow waves and wake heights, pressure distributions on boards and overall drag data.
As part of the work we are developing Computer Aided Design (CAD) tools for fins and surfboards, demos of which can be downloaded from our website. These have an advantage over commercial CAD packages in that they have been specific created for the design of fins and surfboards and hence do not require such a steep learning curve.
[=1]Preliminary computational findings were presented in a paper at the 4th International Surfing Reef Symposium, Natural and Artificial Surfing Reefs, Surf Science and Coastal Management held at Manhattan Beach, California on January 12-14, 2005, and was highlighted in a recent article reviewing the symposium at surfline.com ([ 3]http://www.surfline.com/home/SurfNews/2005_02_24_artificial.cfm)[/]. Part of the work demonstrated that for double-foiled fins (e.g. middle fins), glassed on fins produced less drag than boxed fins which did not have a fillet. However, the argument was not cut and dry as this was not the case for the outer fins.[/]
We have a website (http://cetic.swan.ac.uk/surfs) from which the actual paper can be downloaded, and my e-mail is (N.P.Lavery@swansea.ac.uk) if anyone wants to correspond directly with us regarding any of this work.