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Turbidity Current Dynamics: 2. Simulating Flow Evolution Toward Equilibrium in Idealized Channels
Author(s) -
Traer M. M.,
Fildani A.,
Fringer O.,
McHargue T.,
Hilley G. E.
Publication year - 2018
Publication title -
journal of geophysical research: earth surface
Language(s) - English
Resource type - Journals
eISSN - 2169-9011
pISSN - 2169-9003
DOI - 10.1002/2017jf004202
Subject(s) - mechanics , turbidity current , settling , flow (mathematics) , entrainment (biomusicology) , flow conditions , open channel flow , turbidity , steady state (chemistry) , channel (broadcasting) , geology , thermodynamics , physics , chemistry , geomorphology , oceanography , engineering , structural basin , sedimentary depositional environment , rhythm , acoustics , electrical engineering
This study simulates turbidity currents through a number of idealized channels using a steady, one‐dimensional, depth‐averaged model to determine if modeled flows starting from a wide range of initial conditions might reach an equilibrium state where clear‐water entrainment balances fluid mass lost to flow stripping or overspill processes. To accomplish this, we calculated flow dynamics based on 1,000 sets of randomized initial conditions, identified flows that successfully traversed the system, and then extracted the flow height, velocity, and sediment flux at the channel terminus. We then systematically changed channel and flow properties using a wide range of values and calculated the length required for the simulated currents to reach the new equilibrium conditions. We found that modeled turbidity currents may evolve to a single equilibrium state consistent with the physical channel and flow properties regardless of the initial flow conditions. Additionally, we found that simulated turbidity currents generally required 1–40 km of downflow distance to adjust to new equilibrium conditions resulting from changes in the channel slope, channel height, channel width, coefficient of bed friction, and meander radius of curvature. Changes in sediment grain size and suspension cloud concentration resulted in adjustment lengths exceeding 100 km. Shorter adjustment lengths resulting from flow stripping suggest that this process might play an important role in flow filtering. The fact that modeled flows adjust to new equilibria over tens of kilometers suggests that they are less sensitive to upstream flow conditions in longer channels.