MIXING INDUCED BY OSCILLATORY STRATIFIED FLOW PAST A RIGHT-CIRCULAR CYLINDER

Citation
Mjam. Perera et al., MIXING INDUCED BY OSCILLATORY STRATIFIED FLOW PAST A RIGHT-CIRCULAR CYLINDER, Journal of Fluid Mechanics, 284, 1995, pp. 1-21
Citations number
41
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Mechanics,"Phsycs, Fluid & Plasmas
Journal title
ISSN journal
0022-1120
Volume
284
Year of publication
1995
Pages
1 - 21
Database
ISI
SICI code
0022-1120(1995)284:<1:MIBOSF>2.0.ZU;2-U
Abstract
A series of laboratory experiments was performed to investigate the ov erall mixing characteristics of oscillatory stratified flow past an is olated topography. The experiments were conducted by oscillating a rig ht-circular cylinder in an otherwise quiescent linearly stratified flu id contained in a rectangular basin. The mixing was largely confined t o the turbulent 'core' region around the cylinder. This mixed fluid wa s then injected into the fluid interior of the basin by numerous intru sive tongues. These intrusions were accompanied by return currents of unmixed stratified fluid into the turbulent core. The overall effect o f this mixing process was to increase the potential energy of the flui d in the basin. An expression is derived to relate the rate of change of potential energy of the system to the basin-averaged buoyancy flux. This formula was then used to calculate the mean buoyancy flux from m easurements of the rate of change of potential energy of the fluid sys tem. Basin-averaged diapycnal eddy diffusivities for the experiments w ere evaluated and the results were found to be in good agreement with the predictions of a heuristic model based on the energetics of the mi xing. Observations on the spreading of intrusions and the evolution of the density field are also presented.