Mixing dynamics of turbidity currents interacting with complex seafloor topography

Mohamad M. Nasr-Azadani; Eckart Meiburg; Benjamin Charles Kneller

doi:10.1007/s10652-016-9477-9

Mixing dynamics of turbidity currents interacting with complex seafloor topography

Mohamad M. Nasr-Azadani, Eckart Meiburg, Benjamin Charles Kneller

Geology and Geophysics

University of California at Santa Barbara

Research output: Contribution to journal › Article › peer-review

21 Citations (Scopus)

Abstract

Direct Numerical Simulations are employed to investigate the mixing dynamics of turbidity currents interacting with seamounts of various heights. The mixing properties are found to be governed by the competing effects of turbulence amplification and enhanced dissipation due to the three-dimensional topography. In addition, particle settling is seen to play an important role as well, as it affects the local density stratification, and hence the stability, of the current. The interplay of these different mechanisms results in the non-monotonic dependence of the mixing behavior on the height of the seamount. Regions of dilute lock fluid concentration generally mix more intensely as a result of the seafloor topography, while concentrated lock fluid remains relatively unaffected. For long times, the strongest mixing occurs for intermediate bump heights. Particle settling is seen to cause turbidity currents to mix more intensely with the ambient than gravity currents.

Original language	English
Pages (from-to)	201 -223
Number of pages	23
Journal	Environmental Fluid Mechanics
Volume	18
Issue number	1
Early online date	2 Aug 2016
DOIs	https://doi.org/10.1007/s10652-016-9477-9
Publication status	Published - Feb 2018

Bibliographical note

MN was partially funded via research support to Prof. Kneller’s group from BG Group, BP, ConocoPhillips, DONG, GDF Suez, Hess, Petrobras, RWE Dea, Total, and Statoil. EM acknowledges financial assistance through NSF Grants CBET-0854338, CBET-1067847 and OCE-1061300. The simulations were carried out at the Janus, Epic, and Beach supercomputing facilities. Janus is supported by the National Science Foundation (award number CNS-0821794) and the University of Colorado at Boulder and is a joint effort of the University of Colorado Boulder, the University of Colorado Denver and the National Center for Atmospheric Research. The Epic@iVec supercomputing facility is part of the Pawsey Centre project of the iVec Institute, Australia. Access to the Beach cluster was provided by the Community Surface Dynamics Modeling System (CSDMS) high-performance computing facility at the University of Colorado in Boulder.

Keywords

gravity current
turbidity current
mixing
particle setting
numerical simulations
complex topography

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title = "Mixing dynamics of turbidity currents interacting with complex seafloor topography",

abstract = "Direct Numerical Simulations are employed to investigate the mixing dynamics of turbidity currents interacting with seamounts of various heights. The mixing properties are found to be governed by the competing effects of turbulence amplification and enhanced dissipation due to the three-dimensional topography. In addition, particle settling is seen to play an important role as well, as it affects the local density stratification, and hence the stability, of the current. The interplay of these different mechanisms results in the non-monotonic dependence of the mixing behavior on the height of the seamount. Regions of dilute lock fluid concentration generally mix more intensely as a result of the seafloor topography, while concentrated lock fluid remains relatively unaffected. For long times, the strongest mixing occurs for intermediate bump heights. Particle settling is seen to cause turbidity currents to mix more intensely with the ambient than gravity currents.",

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author = "Nasr-Azadani, {Mohamad M.} and Eckart Meiburg and Kneller, {Benjamin Charles}",

note = "MN was partially funded via research support to Prof. Kneller{\textquoteright}s group from BG Group, BP, ConocoPhillips, DONG, GDF Suez, Hess, Petrobras, RWE Dea, Total, and Statoil. EM acknowledges financial assistance through NSF Grants CBET-0854338, CBET-1067847 and OCE-1061300. The simulations were carried out at the Janus, Epic, and Beach supercomputing facilities. Janus is supported by the National Science Foundation (award number CNS-0821794) and the University of Colorado at Boulder and is a joint effort of the University of Colorado Boulder, the University of Colorado Denver and the National Center for Atmospheric Research. The Epic@iVec supercomputing facility is part of the Pawsey Centre project of the iVec Institute, Australia. Access to the Beach cluster was provided by the Community Surface Dynamics Modeling System (CSDMS) high-performance computing facility at the University of Colorado in Boulder. ",

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AB - Direct Numerical Simulations are employed to investigate the mixing dynamics of turbidity currents interacting with seamounts of various heights. The mixing properties are found to be governed by the competing effects of turbulence amplification and enhanced dissipation due to the three-dimensional topography. In addition, particle settling is seen to play an important role as well, as it affects the local density stratification, and hence the stability, of the current. The interplay of these different mechanisms results in the non-monotonic dependence of the mixing behavior on the height of the seamount. Regions of dilute lock fluid concentration generally mix more intensely as a result of the seafloor topography, while concentrated lock fluid remains relatively unaffected. For long times, the strongest mixing occurs for intermediate bump heights. Particle settling is seen to cause turbidity currents to mix more intensely with the ambient than gravity currents.

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Mixing dynamics of turbidity currents interacting with complex seafloor topography

Abstract

Bibliographical note

Keywords

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