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Development of the flow field of a point force in an infinite fluid

Published online by Cambridge University Press:  19 April 2006

C. Sozou
Affiliation:
Department of Applied Mathematics and Computing Science, University of Sheffield, England

Abstract

By means of similarity principles an analytical solution is constructed for the development of the linear flow field due to the instantaneous application of a constant point force in an infinite liquid. If the force is applied at the origin O and if ν denotes distance from O, ν denotes the coefficient of kinematic viscosity of the fluid and t the time from the application of the force, the solution constructed exhibits the following features. Initially the flow field set up has a dipole structure with centre at O and axis along the direction of the impressed force. At a station r this dipole structure persists so long as 4νt [Lt ] r2. In an axial cross-section the field lines form two sets of closed loops about two stagnation points in the equatorial plane. The stagnation points occur at r = 1.76(νt)½ and thus propagate to infinity with speed 0.88(ν/t)½. The steady state is reached algebraically.

Type
Research Article
Copyright
© 1979 Cambridge University Press

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References

Happel, J. & Brenner, H. 1965 Low Reynolds Number Hydrodynamics. Prentice-Hall.
Lighthill, M. J. 1976 SIAM Rev. 18, 161.
Lighthill, M. J. 1978 Waves in Fluids. Cambridge University Press.
Sozou, C. & Pickering, W. M. 1977 J. Fluid Mech. 80, 673.