Decay of dipolar vortex structures in a stratified fluid
作者:
J. B. Flo´r,
G. J. F. van Heijst,
R. Delfos,
期刊:
Physics of Fluids
(AIP Available online 1995)
卷期:
Volume 7,
issue 2
页码: 374-383
ISSN:1070-6631
年代: 1995
DOI:10.1063/1.868635
出版商: AIP
数据来源: AIP
摘要:
In this paper the viscous decay of dipolar vortex structures in a linearly stratified fluid is investigated experimentally, and a comparison of the experimental results with simple theoretical models is made. The dipoles are generated by a pulsed horizontal injection of fluid. In a related experimental study by Flo´r and van Heijst [J. Fluid Mech.279, 101 (1994)], it was shown that, after the emergence of the pancake‐shaped vortex structure, the flow is quasi‐two‐dimensional and decays due to the vertical diffusion of vorticity and entrainment of ambient irrotational fluid. This results in an expansion of the vortex structure. Two decay models with the horizontal flow based on the viscously decaying Lamb–Chaplygin dipole, are presented. In a first model, the thickness and radius of the dipole are assumed constant, and in a second model also the increasing thickness of the vortex structure is taken into account. The models are compared with experimental data obtained from flow visualizations and from digital analysis of particle‐streak photographs. Although both models neglect entrainment and the decay is modeled by diffusion only, a reasonable agreement with the experiments is obtained. ©1995 American Institute of Physics.
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