Journal of Fluid Mechanics

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The front speed of intrusions into a continuously stratified medium

DIOGO BOLSTERa1, ALICE HANGa1 and P. F. LINDENa1

a1 Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 92037, USA dbolster@ucsd.edu

Abstract

This paper examines intrusive Boussinesq gravity currents, propagating into a continuously stratified fluid. We develop a model, based on energy arguments, to predict the front speed of such an intrusive gravity current from a lock release. We find that the depth at which the intrusion occurs, which corresponds to the level of neutral buoyancy (i.e. the depth where the intrusion density equals the stratified fluid density), affects the front speed. The maximum speeds occur when the intrusion travels along the top and bottom boundaries and the minimum speed occurs at mid-depth. Experiments and numerical simulations were conducted to compare to the theoretically predicted values, and good agreement was found.

(Received June 22 2007)

(Revised October 01 2007)

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