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The force on a slender fish-like body

Published online by Cambridge University Press:  29 March 2006

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

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
Copyright
© 1973 Cambridge University Press

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References

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Newman, J. N. & Wu, T. Y. 1973 A generalized slender-body theory for fish-like forms. J. Fluid Mech. 57, 673693.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.