To CFD or not to CFD that is the question? - Part I

'We call it theory when we know about something but nothing works, and practice when everything works but nobody knows why' -- Albert Einstein

Long before man first flew, physicists had been searching for mathematical models to describe, predict and measure the effects of fluid flow. The incentive then was mostly intellectual though it did have implications for boats and ships. When man eventually flew, this research took on a greater significance. The incentive now was not only to understand the problem better and thus gain valuable insight, but also to be able to measure lift, and drag, and moments, and thus predict the performance of aircraft.

Physical methods of testing - wind tunnels, flumes and tanks - are not only time consuming and expensive, they are also not always very accurate in a quantitive sense. Test a simple wing section in three different wind tunnels and you will more than likely get three different results depending, to a large extent, upon the turbulence level in each tunnel - and none of them will agree with reality. Gliders in free flight nearly always beat the estimates of performance gleaned from wind tunnel tests, principally because of different types and levels of turbulence in the atmosphere compared to the tunnel.

To read the remainder of this and many other articles, please purchase your copy of the April 2006 edition of Seahorse International Sailing available at selected newsstands or by calling: + 44 (0) 1590 671899 or by email at: info@seahorse.co.uk

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