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Full-Text Articles in Life Sciences

Rotational Lift: Something Different Or More Of The Same?, Jeffrey A. Walker Phd Dec 2002

Rotational Lift: Something Different Or More Of The Same?, Jeffrey A. Walker Phd

Faculty Publications

This paper addresses the question, do the rotational forces in the hovering fruit fly Drosophila melanogaster reflect something different (the Magnus effect) or more of the same (circulatory-and-attached-vortex force)? The results of an unsteady blade-element model using empirically derived force coefficients from translating (root-oscillating) wings are compared with recent results derived from both the measured forces on a dynamically scaled Drosophila wing and the computational fluid dynamic (CFD)-modeled forces on a virtual Drosophila wing. The behavior of the forces in all three models during wing rotation supports the hypothesis that rotational lift is not a novel aerodynamic mechanism but is …


Fluid Dynamics Of Flapping Aquatic Flight In The Bird Wrasse: Three-Dimensional Unsteady Computations With Fin Deformation, Ravi Ramamurti, William C. Sandberg, Rainald Lӧhner, Jeffrey A. Walker Phd, Mark W. Westneat Oct 2002

Fluid Dynamics Of Flapping Aquatic Flight In The Bird Wrasse: Three-Dimensional Unsteady Computations With Fin Deformation, Ravi Ramamurti, William C. Sandberg, Rainald Lӧhner, Jeffrey A. Walker Phd, Mark W. Westneat

Faculty Publications

Many fishes that swim with the paired pectoral fins use fin-stroke parameters that produce thrust force from lift in a mechanism of underwater flight. These locomotor mechanisms are of interest to behavioral biologists, biomechanics researchers and engineers. In the. present study, we performed the first three-dimensional unsteady computations of fish swimming with oscillating and deforming fins. The objective of these computations was to investigate the fluid dynamics of force production associated with the flapping aquatic flight of the bird wrasse Gomphosus varius. For this computational work, we used the geometry of the wrasse and its pectoral fin, and previously measured …


Performance Limits Of Labriform Propulsion And Correlates With Fin Shape And Motion, Jeffrey A. Walker Phd, Mark W. Westneat Jan 2002

Performance Limits Of Labriform Propulsion And Correlates With Fin Shape And Motion, Jeffrey A. Walker Phd, Mark W. Westneat

Faculty Publications

Labriform locomotion, which is powered by oscillating the paired pectoral fins, varies along a continuum from rowing the fins back and forth to flapping the fins up and down. It has generally been assumed (i) that flapping is more mechanically efficient than rowing, a hypothesis confirmed by a recent simulation experiment, and (ii) that flapping should be associated with wing-shaped fins while rowing should be associated with paddle-shaped fins, To determine whether these hypotheses and the results of the simulation experiment are consistent with natural variation, we compared the steady swimming performance (critical swimming speed) of four species of labrid …