Journal ArticleDOI
Experiments on the dynamics of a gravity current head
Rex Britter,J. E. Simpson +1 more
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In this paper, the inviscid gravity current head is considered and the mixing appears to occur through Kelvin-Helmholtz billows generated on the front of the head.Abstract:
Some of the dense fluid at the front of an advancing gravity current is observed to be mixed with the ambient fluid. This process continues when the cross-stream non-uniformities at the head of the current are suppressed by advancing the floor beneath the head. In the resulting two-dimensional flow regular billows are visible. This paper considers experimentally and analytically the inviscid gravity current head and specifically includes the observed mixing at the head. Experimental results were obtained with an apparatus in which the head of the gravity current was brought to rest by an opposing uniform flow. The mixing appears to occur through Kelvin-Helmholtz billows generated on the front of the head and controls the dynamics of the head. A momentum balance is used to analyse the flow and the problem is closed by quantitatively introducing the billow structure.read more
Citations
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The propagation of two-dimensional and axisymmetric viscous gravity currents over a rigid horizontal surface
TL;DR: In this paper, the viscous gravity current that results when fluid flows along a rigid horizontal surface below fluid of lesser density is analyzed using a lubrication-theory approximation, and it is shown that the effect on the gravity current of the motion in the upper fluid can be expressed as a condition of zero shear on the unknown upper surface of the current.
Journal ArticleDOI
The slumping of gravity currents
Herbert E. Huppert,J. E. Simpson +1 more
TL;DR: In this article, it is shown that the gravity current can pass through three states: a slumping phase, a viscous phase, and a purely inertial phase, where the buoyancy force of the intruding fluid is balanced by the inertial force.
Journal ArticleDOI
The structure and fluid mechanics of turbidity currents: a review of some recent studies and their geological implications
Ben Kneller,Clare Buckee +1 more
TL;DR: The literature on the structure and behaviour of gravity currents is reviewed in this paper, with particular attention to turbidity currents, though reference is also made to comparable behaviour in pyroclastic flows.
Journal ArticleDOI
Analysis and direct numerical simulation of the flow at a gravity-current head. Part 1. Flow topology and front speed for slip and no-slip boundaries
TL;DR: In this paper, a detailed analysis of the flow structure at the foremost part of the front, where no previous high-resolution data were available, was performed, based on spectral and spectral-element discretizations and compact finite differences.
Journal ArticleDOI
Gravity currents produced by instantaneous releases of a heavy fluid in a rectangular channel
James W. Rottman,J. E. Simpson +1 more
TL;DR: In this paper, a finite volume of homogeneous fluid was released instantaneously into another fluid of slightly lower density and the experiments were performed in a channel of rectangular cross-section, and the two fluids used were salt water and fresh water.
References
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Journal ArticleDOI
On density effects and large structure in turbulent mixing layers
Garry L. Brown,Anatol Roshko +1 more
TL;DR: In this article, Spark shadow pictures and measurements of density fluctuations suggest that turbulent mixing and entrainment is a process of entanglement on the scale of the large structures; some statistical properties of the latter are used to obtain an estimate of entrainedment rates, and large changes of the density ratio across the mixing layer were found to have a relatively small effect on the spreading angle.
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Gravity currents and related phenomena
TL;DR: In this paper, the authors present a broad investigation into the properties of steady gravity currents, in so far as they can be represented by perfect-fluid theory and simple extensions of it (like the classical theory of hydraulic jumps) that give a rudimentary account of dissipation.
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The engineer grapples with nonlinear problems
TL;DR: The most important engineering problems and the mathematical concepts and methods involved in their treatment are indicated in the following table as discussed by the authors ; however, it is not possible to give an exhaustive list of all types of problems which require the applications of advanced analytical methods.
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Experiments on instability and turbulence in a stratified shear flow
TL;DR: In this paper, a study of turbulence which results from Kelvin-Helmholtz instability at the interface between two miscible fluids in a two-dimensional shear flow in the laboratory is described.
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Effects of the lower boundary on the head of a gravity current
TL;DR: In this paper, an experimental measurement of the advancing head of a gravity current is described, and it is concluded that the lower boundary plays an essential role in determining the substructure of the head and that this originates in convective instability as the head rides over less dense fluid.