Recent experimental studies have presented the lift and drag coefficients for a range of oar blades. However, these studies were not able to provide insight into the mechanisms of lift and drag generation. The aims of this study, therefore, were to model the flow around an oar blade using computational fluid dynamics (CFD), and to validate this model against experimental data.
A CFD model of the flow around oar blades was constructed using Fluent (ANSYS Inc., USA). To evaluate the performance of the model the geometries of the blade, domain and fluid free stream velocity of the CFD model simulated published quarter scale experimental measurements. The geometries were determined directly from the quarter scale blades used previously, and the blades were tested at a range of static angles of attack, representative of the motion of the blade from catch to finish. In a second series of simulations, the blade geometries and the fluid velocity were scaled to full size. A k-w SST RANS turbulence model was used as the solver, as it is capable of resolving the turbulence at the blade surface (in the near wall region) and in the bulk of the flow, at all angles of attack.
A close agreement was achieved between experimental and CFD lift and drag coefficients, demonstrating the validity of the model. When CFD simulations of the blade geometry and fluid velocity were scaled to full size, lift was similar to quarter scale, but drag was reduced at all angles of attack. This reduction in drag at full size can be explained by the shape of the blade. For a flat plate with similar Reynolds number to those seen here, drag should be constant at increasing velocity. However, the curvature of the oar simulated here influenced fluid flow over and around the blade.
© Copyright 2008 The Engineering of sport 7, Volume 1. Published by Springer. All rights reserved.
|Subjects:||hydrodynamics rowing sports equipment modelling|
|Notations:||technical and natural sciences|
|Published in:||The Engineering of sport 7, Volume 1|
|Editors:||M. Estivalet, P. Brisson|