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The force on a slender fish-like body

Published online by Cambridge University Press:  29 March 2006

J. N. Newman
J. N. Newman
Affiliation:
Department of Ocean Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
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Abstract

The force acting on a fish-like body with combined thickness and lifting effects is analysed on the assumption of inviscid flow. A general expression is developed for the pressure force on the body, which is analogous to the momentum-flux analysis for non-lifting bodies in classical hydrodynamics. For bodies with constant volume, the mean drag (or propulsive) force is expressed in terms of a contour integral around the vortex sheet behind the body. Attention is focused on the case of steady-state motion with constant angle of attack, and the induced drag is analysed for finned axisymmetric bodies using the slender-body approximation developed by Newman & Wu (1973). Unlike earlier results of Lighthill (1970), the lift–drag ratio in this case depends on the body thickness.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 58 , Issue 4 , 22 May 1973 , pp. 689 - 702
Copyright
© 1973 Cambridge University Press

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References

Lighthill, M. J. 1960 Note on the swimming of slender fish. J. Fluid Mech. 9, 305–317.Google Scholar
Lighthill, M. J. 1970 Aquatic animal propulsion of high hydromechanical efficiency. J. Fluid Mech. 44, 265–300.Google Scholar
Lighthill, M. J. 1971 Large-amplitude elongated-body theory of fish locomotion. Proc. Roy. Soc. B 179, 125–138.Google Scholar
Newman, J. N. & Wu, T. Y. 1973 A generalized slender-body theory for fish-like forms. J. Fluid Mech. 57, 673–693.Google Scholar
Wu, T. Y. & Newman, J. N. 1972 Unsteady flow around a slender fish-like body. Proc. International Symposium on Directional Stability and Control of Bodies Moving in Water. London: Institution of Mechanical Engineers.