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Show RESEARCH POSTERS ON THE HILL SPRING 2007 87 Effects of Various Angles of Attack on Flow Through Bristled Wings Ginger Dobie and Laura Miller Department of Mathematics Tiny insects use a process called ‘clap and fling’ to augment the lift forces generated during flight. The one disadvantage to using this method is the drag forces created when the wings fling apart are very large. Many tiny insects have bristled rather than solid wings, and it is thought that using the bristled wings might help reduce drag when the wings are pulled apart. The basic idea is that the wings might act as ‘leaky rakes’ during fling, meaning that the air travels through the wing reducing the drag forces generated. When the wings are in translation, they act like solid plates because the force acting normal to the wing is reduced. This mechanism is only possible if the wings flap at an intermediate Reynolds number where there is a sharp transition between arrays of cylinders acting as solids or porous media. To investigate whether or not this mechanism is feasible, we looked at leakiness for two different Reynolds numbers, ten angles of attack and three spacings. We used experiments rather than mathematical simulations study this problem due to the computational requirements of solving the Navier-Stokes equation in three dimensions for a number of configurations. From our experiments we found that leakiness decreases as the angle of attack decreases. We also found that leakiness decreases as the Reynolds number decreases. It seems likely that the wings act as solid plates for high angles of attack at higher Reynolds numbers, and as solid plates for lower angles of attack at lower Reynolds numbers. Ginger Dobie is supported by funding from The University of Utah, Department of Mathematics, Vertical Integration of Research and Education. |
