Hostname: page-component-586b7cd67f-t7czq Total loading time: 0 Render date: 2024-11-26T06:23:24.907Z Has data issue: false hasContentIssue false
  • English
  • Français

Flexibility effects on vortex formation of translating plates

Published online by Cambridge University Press:  18 April 2011

DAEGYOUM KIM  and
MORTEZA GHARIB
DAEGYOUM KIM
Affiliation:
Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125, USA
MORTEZA GHARIB*
Affiliation:
Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125, USA
*
†Email address for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

Vortex structures made by impulsively translating low aspect-ratio plates are studied experimentally using defocusing digital particle image velocimetry. The investigation of translating plates with a 90° angle of attack is important since it is a fundamental model for a better understanding of drag-based propulsion systems. Rectangular flat-rigid, flexible and curved-rigid thin plates with the same aspect ratio are studied in order to develop qualitative and quantitative understanding of their vortex structures and hydrodynamic forces. We find that the vortex formation processes of all three cases are drastically different from each other. The interaction of leading-edge vortices and tip flow near the tip region is an important mechanism to distinguish vortex patterns among these three cases. The drag trends of three cases are correlated closely with vortex structure and circulation. The initial peak of hydrodynamic force in the flexible plate case is not as large as the initial peak of the flat and curved rigid plate cases during the acceleration phase. However, after the initial peak, the flexible plate generates a large force comparable to that of the flat-rigid plate case in spite of its deformed shape, which results from the slow development of the vortex structure.

JFM classification

Biological Fluid Dynamics: Propulsion Biological Fluid Dynamics: Swimming/flying Vortex Flows: Vortex dynamics
Type
Papers
Information
Journal of Fluid Mechanics , Volume 677 , 25 June 2011 , pp. 255 - 271
Copyright
Copyright © Cambridge University Press 2011

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Birch, J. M. & Dickinson, M. H. 2001 Spanwise flow and the attachment of the leading-edge vortex on insect wings. Nature 412, 729–733.Google Scholar
Combes, S. A. & Daniel, T. L. 2003 a Flexural stiffness in insect wings. Part I. Scaling and the influence of wing venation. J. Exp. Biol. 206, 2979–2987.Google Scholar
Combes, S. A. & Daniel, T. L. 2003 b Flexural stiffness in insect wings. Part II. Spatial distribution and dynamic wing bending. J. Exp. Biol. 206, 2989–2997.Google Scholar
Combes, S. A. & Daniel, T. L. 2003 c Into thin air: contributions of aerodynamic and inertial-elastic forces to wing bending in the hawkmoth. Manduca sexta. J. Exp. Biol. 206, 2999–3006.CrossRefGoogle Scholar
Dickinson, M. H. & Götz, K. G. 1993 Unsteady aerodynamic performance of model wings at low Reynolds-numbers. J. Exp. Biol. 174, 45–64.Google Scholar
Drucker, E. G. & Lauder, G. V. 1999 Locomotor forces on a swimming fish: Three-dimensional vortex wake dynamics quantified using digital particle image velocimetry. J. Exp. Biol. 202, 2393–2412.Google Scholar
Ellington, C. P., Van den Berg, C., Willmott, A. P. & Thomas, A. L. R. 1996 Leading-edge vortices in insect flight. Nature 384, 626–630.Google Scholar
Gharib, M., Rambod, E. & Shariff, K. 1998 A universal time scale for vortex ring formation. J. Fluid Mech. 360, 121–140.CrossRefGoogle Scholar
Koumoutsakos, P. & Shiels, D. 1996 Simulations of the viscous flow normal to an impulsively started and uniformly accelerated flat plate. J. Fluid Mech. 328, 177–227.Google Scholar
Maxworthy, T. 1979 Experiments on the Weis-Fogh mechanism of lift generation by insects in hovering flight. Part 1. Dynamics of the fling. J. Fluid Mech. 93, 47–63.CrossRefGoogle Scholar
Mountcastle, A. M. & Daniel, T. L. 2009 Aerodynamic and functional consequences of wing compliance. Exp. Fluids 46, 873–882.Google Scholar
Pereira, F. & Gharib, M. 2002 Defocusing digital particle image velocimetry and the three-dimensional characterization of two-phase flows. Meas. Sci. Technol. 13, 683–694.CrossRefGoogle Scholar
Pereira, F., Stuer, H., Graff, E. C. & Gharib, M. 2006 Two-frame 3D particle tracking. Meas. Sci. Technol. 17, 1680–1692.Google Scholar
Pullin, D. I. & Wang, Z. J. 2004 Unsteady forces on an accelerating plate and application to hovering insect flight. J. Fluid Mech. 509, 1–21.CrossRefGoogle Scholar
Ringuette, M. J., Milano, M. & Gharib, M. 2007 Role of the tip vortex in the force generation of low-aspect-ratio normal flat plates. J. Fluid Mech. 581, 453–468.Google Scholar
Spedding, G. R., Rosen, M. & Hedenstrom, A. 2003 A family of vortex wakes generated by a thrush nightingale in free flight in a wind tunnel over its entire natural range of flight speeds. J. Exp. Biol. 206, 2313–2344.CrossRefGoogle Scholar
Srygley, R. B. & Thomas, A. L. R. 2002 Unconventional lift-generating mechanisms in free-flying butterflies. Nature 420, 660–664.Google Scholar
Vogel, S. 1996 Life in Moving Fluids. Princeton University Press.Google Scholar
Wang, Z. J. 2004 The role of drag in insect hovering. J. Exp. Biol. 207, 4147–4155.Google Scholar
Willert, C. E. & Gharib, M. 1992 Three-dimensional particle imaging with a single camera. Exp. Fluids 12, 353–358.Google Scholar
Wu, J. C. 1981 Theory for aerodynamic force and moment in viscous flows. AIAA J. 19, 432–441.CrossRefGoogle Scholar
Young, J., Walker, S. M., Bomphrey, R. J., Taylor, G. K. & Thomas, A. L. R. 2009 Details of insect wing design and deformation enhance aerodynamic function and flight efficiency. Science 325, 1549–1552.Google Scholar