Hostname: page-component-78c5997874-g7gxr Total loading time: 0 Render date: 2024-11-06T07:19:55.165Z Has data issue: false hasContentIssue false

Mixed region collapse with internal wave generation in a density-stratified medium

Published online by Cambridge University Press:  28 March 2006

Jin Wu
Affiliation:
HYDRONAUTICS, Incorporated, Laurel, Maryland

Abstract

An experiment has been conducted modelling a two-dimensional mixed region collapsing in a continuously density-stratified medium. The process of collapse can be divided into three stages. Empirical formulae have been derived to describe the process of the first two stages, during which gravitational effects determine the modelling criterion. The collapse in the final stage is complicated by viscous effects; a ratio between the Froude number and the Reynolds number seems to provide a probable modification of the time scale.

The pattern of internal waves generated by the initial impulsive collapse of this mixed region can be represented by moving rays connecting either wave crests or troughs. These rays move away from the collapse centre and at the same time decrease their slopes from the horizontal. A simpler steady-state wave pattern generated by an oscillating plunger has also been studied. Taken together, these experimental results are interpreted to show that the energy density of the collapse is skewed toward high frequencies and is peaked at 8/10 of the Brunt-Väisälä frequency of the medium.

Type
Research Article
Copyright
© 1969 Cambridge University Press

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

Gortler, H. 1943 Über eine Schwingungsercheinung in Flüssigkeiten mit stabiler Dichteschichtung Z. angew. Math. Mech. 23, 65.Google Scholar
Lighthill, M. J. 1960 Studies on magneto-hydromagnetic waves and other anisotropic wave motions Trans. Roy. Soc. A 252, 397.Google Scholar
Lofquist, K. 1960 Flow and stress near an interface between stratified liquids Phys. Fluids, 3, 158.Google Scholar
Mowbray, D. E. & Rarity, S. H. 1967 A theoretical and experimental investigation of the phase configuration of internal waves of small amplitude in a density stratified liquid J. Fluid Mech. 28, 1.Google Scholar
Schlichting, H. 1958 Boundary Layer Theory. New York: McGraw-Hill.
Schooley, A. H. & Stewart, R. W. 1963 Experiments with a self-propelled body submerged in a fluid with a vertical density gradient J. Fluid Mech. 15, 83.Google Scholar
Wong, K. K. 1965 On internal gravity waves generated by local disturbance. Hydronautics, Inc. Tech. Rep. 231–5.Google Scholar