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Numerical investigation of particulate gravity currents.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Numerical investigation of particulate gravity currents./
Author:	Shringarpure, Mrugesh Surendra.
Description:	1 online resource (241 pages)
Notes:	Source: Dissertation Abstracts International, Volume: 76-01(E), Section: B.
Contained By:	Dissertation Abstracts International76-01B(E).
Subject:	Mechanical engineering. -
Online resource:	click for full text (PQDT)
ISBN:	9781321184761

Numerical investigation of particulate gravity currents.
Shringarpure, Mrugesh Surendra.

Numerical investigation of particulate gravity currents. - 1 online resource (241 pages)

Source: Dissertation Abstracts International, Volume: 76-01(E), Section: B.

Thesis (Ph.D.)--University of Florida, 2013.

Includes bibliographical references

Gravity or density currents are horizontal flows driven by hydrostatic pressure gradients caused due to density differences under the influence of gravity. In other words, gravity currents are caused when fluids with different density interact in an unconstrained environment. This involves a current spreading into the column of ambient fluid at the bottom (heavier than the ambient) or top (lighter than the ambient) or at some height from the bottom (the ambient is stratified and the current density lies between the stratification limits). Gravity currents are ubiquitous in nature and various industrial scenarios. This work considers gravity currents that are driven by active scalars like sediments, dust particles, powder snow etc, and initiated by continuous discharge of current. In particular I will consider submarine particulate gravity currents also known as turbidity currents. Three aspects of these currents are analyzed in detail. In this work it is shown that the front condition of gravity current initiated by constant discharge into the ambient can be substantially influenced by ambient flow direction. From theoretical considerations an expression for front condition based on the current depth ratio and ambient flow direction is derived. These results are validated using numerical simulations that were performed as a part of this work and experimental observations available in the literature. Currents initiated by variable inflow are also simulated and their front condition is compared with steady fronts. The interaction of turbulence and stratification caused by suspended sediments in turbidity currents is studied using a mathematical model that considers mono and bi-disperse suspension of sediment. Through numerical simulations, turbulence suppression mechanisms controlled by stratification are identified and characterized using the parameters that govern the flow. The key parameters are Reynolds number (measure of flow intensity), Richardson number (measure of stratification) and sediment particle settling velocity (measure of particle size). Parametric grouping Richardson number x Settling velocity is identified that quantifies turbulence suppression. A scaling relation for this parametric grouping with the flow intensity is also proposed. From bi-disperse suspension simulations, it is shown that adding fine sediments into the suspension helps the current carry large size sediment particles. Furthermore, it leads to increase in the carrying capacity of turbidity currents.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9781321184761Subjects--Topical Terms:

557493
Mechanical engineering.
Index Terms--Genre/Form:

554714
Electronic books.

Numerical investigation of particulate gravity currents.
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245 1 0 $a Numerical investigation of particulate gravity currents.
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300 $a 1 online resource (241 pages)
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500 $a Source: Dissertation Abstracts International, Volume: 76-01(E), Section: B.
500 $a Adviser: Sivaramakrishnan Balachandar.
502 $a Thesis (Ph.D.)--University of Florida, 2013.
504 $a Includes bibliographical references
520 $a Gravity or density currents are horizontal flows driven by hydrostatic pressure gradients caused due to density differences under the influence of gravity. In other words, gravity currents are caused when fluids with different density interact in an unconstrained environment. This involves a current spreading into the column of ambient fluid at the bottom (heavier than the ambient) or top (lighter than the ambient) or at some height from the bottom (the ambient is stratified and the current density lies between the stratification limits). Gravity currents are ubiquitous in nature and various industrial scenarios. This work considers gravity currents that are driven by active scalars like sediments, dust particles, powder snow etc, and initiated by continuous discharge of current. In particular I will consider submarine particulate gravity currents also known as turbidity currents. Three aspects of these currents are analyzed in detail. In this work it is shown that the front condition of gravity current initiated by constant discharge into the ambient can be substantially influenced by ambient flow direction. From theoretical considerations an expression for front condition based on the current depth ratio and ambient flow direction is derived. These results are validated using numerical simulations that were performed as a part of this work and experimental observations available in the literature. Currents initiated by variable inflow are also simulated and their front condition is compared with steady fronts. The interaction of turbulence and stratification caused by suspended sediments in turbidity currents is studied using a mathematical model that considers mono and bi-disperse suspension of sediment. Through numerical simulations, turbulence suppression mechanisms controlled by stratification are identified and characterized using the parameters that govern the flow. The key parameters are Reynolds number (measure of flow intensity), Richardson number (measure of stratification) and sediment particle settling velocity (measure of particle size). Parametric grouping Richardson number x Settling velocity is identified that quantifies turbulence suppression. A scaling relation for this parametric grouping with the flow intensity is also proposed. From bi-disperse suspension simulations, it is shown that adding fine sediments into the suspension helps the current carry large size sediment particles. Furthermore, it leads to increase in the carrying capacity of turbidity currents.
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538 $a Mode of access: World Wide Web
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655 7 $a Electronic books. $2 local $3 554714
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