Journal of Fluid Mechanics

Table of Contents - Volume 147 - 1984  


Shallow flow over an isolated obstacle

V. R.  Lamb a1 and R. E.  Britter a2
a1 Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina 27650
a2 Department of Engineering, University of Cambridge, England

Article author query
lamb vr   [Google Scholar] 
britter re   [Google Scholar] 
 

Abstract

This is a study of how certain geometrical and flow parameters affect the tendency of a fluid to flow around rather than over a single obstacle of simple shape in a homogeneous non-rotating fluid. A series of numerical experiments was conducted with a finite-difference model of such a shallow flow, assuming a hydrostatic pressure distribution. The results demonstrate how the flow over a three-dimensional obstacle deviates from the patterns established for a two-dimensional ridge. Measures are suggested for quantitative assessment of the tendency to flow around as a function of relative hill height and Froude number.

A series of laboratory experiments was also performed, examining the motions of two superposed homogeneous layers of fluid past an isolated obstacle in a towing tank. The resulting motion of the interface was found to agree with the results of the numerical experiments. The laboratory experiments also extended the understanding gained from the numerical experiments. Flow-visualization techniques were employed to aid in the qualitative assessment of the flow around the obstacles and its dependence on hill and flow parameters. In particular, these techniques demonstrated the impingement of the interface on the obstacle, and its dependence on flow speed and hill height.

(Published Online April 20 2006)
(Received September 7 1982)
(Revised May 25 1984)


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