Journal ArticleDOI
Self-accelerating turbidity currents
TLDR
In this article, approximate layer-averaged equations describing the mechanics of turbid underflows are derived and the authors show that the self-acceleration predicted by the three-equation model is so strong that the energy constraint fails to be satisfied.Abstract:
Approximate layer-averaged equations describing the mechanics of turbid underflows are derived. Closure of the equations describing the balance of fluid mass, sediment mass, and mean flow momentum provides for the delineation of a three-equation model. A description of sediment exchange with the bed allows for the possibility of a self-accelerating turbidity current in which sediment entrainment from the bed is linked to flow velocity. A consideration of the balance of the mean energy of the turbulence yields a constraint on physically realistic solutions to the three-equation model. It is shown that the self-acceleration predicted by the three-equation model is so strong that the energy constraint fails to be satisfied. In particular, the turbulent energy consumed in entraining new bed sediment exceeds the supply of energy to the turbulence, so that the turbulence, and thus the turbidity current, must die. The problem is rectified by the formulation of a four-equation model, in which an explicit accounting is made of the mean energy of the turbulence. Sediment entrainment from the bed is linked to the level of turbulence in the four-equation model. Self-acceleration is again predicted, although it is somewhat subdued compared with that predicted by the three-equation model. The predictions of both models are summarized over a wide range of conditions.read more
Citations
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Journal ArticleDOI
The physical character of subaqueous sedimentary density flows and their deposits
Thierry Mulder,Jan Alexander +1 more
TL;DR: A simple classification of sedimentary density flows, based on physical flow properties and grain-support mechanisms, and briefly discusses the likely characteristics of the deposited sediments is presented in this paper.
Journal ArticleDOI
Marine hyperpycnal flows: initiation, behavior and related deposits. A review
TL;DR: Hyperpycnites differ from other turbidites because of their well-developed inversely graded facies and intrasequence erosional contacts as discussed by the authors, which can transport a considerable volume of sediment to ocean basins.
Journal ArticleDOI
Subaqueous sediment density flows: Depositional processes and deposit types
TL;DR: In this article, the authors summarized the processes by which density flows deposit sediment and proposed a new single classification for the resulting types of deposit, which is consistent with previous models of spatial decelerating (dissipative) dilute flow.
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
Turbidity Currents and Their Deposits
Eckart Meiburg,Ben Kneller +1 more
TL;DR: A survey of the current state of the art on turbidity currents with an emphasis on their fluid mechanics is presented in this paper, highlighting the significant role these currents play within the global sediment cycle, and their importance in environmental processes and in the formation of hydrocarbon reservoirs.
References
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Book
Buoyancy Effects in Fluids
TL;DR: In this article, the authors introduce linear internal waves and herar flows in a stratified fluid and double-diffusive convection in stably stratified fluids, and show that the shear flows can produce turbulence.
Mathematical Models of turbulence
Brian Launder,D. B. Spalding +1 more
TL;DR: In this article, turbulence and melange models are used to model models of mathematical models for fluides reference record created on 2005-11-18, modified on 2016-08-08.
Journal ArticleDOI
Turbulent entrainment in stratified flows
T. H. Ellison,J. S. Turner +1 more
TL;DR: In this article, it is assumed that the entrainment is proportional to the velocity of the layer multiplied by an empirical function, E(Ri), of the overall Richardson number for the layer defined by Ri = g(ρa - ρ) h/ρa V2.
Journal ArticleDOI
Self-formed straight rivers with equilibrium banks and mobile bed. Part 1. The sand-silt river
TL;DR: In this paper, the authors formulated a fluid flow model with a series of approximate but reasonable assumptions for straight channels with non-cohesive sand and silt banks and showed that the model can be applied to a more general treatment of natural rivers, which would include various complicating factors such as meandering, sediment sorting and seepage.
Journal ArticleDOI
Auto-suspension of transported sediment; turbidity currents
TL;DR: In this article, it has been shown that the concentration of suspended solids, which being heavier than the fluid tend to fall through it, must always increase downwards towards the bed, whereas the concentrations of fine sediment grades present in rivers are often found to increase upwards instead of downwards.