High-resolution simulations of turbidity currents

Edward Biegert,Eckart Meiburg,Raphael Ouillon,Bernhard Vowinckel

doi:10.1186/s40645-017-0147-4

Edward Biegert, Eckart Meiburg + Show 2 more

Open Access

https://doi.org/10.1186/s40645-017-0147-4

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Abstract

We employ direct numerical simulations of the three-dimensional Navier-Stokes equations, based on a continuum formulation for the sediment concentration, to investigate the physics of turbidity currents in complex situations, such as when they interact with seafloor topography, submarine engineering infrastructure and stratified ambients. In order to obtain a more accurate representation of the dynamics of erosion and resuspension, we have furthermore developed a grain-resolving simulation approach for representing the flow in the high-concentration region near and within the sediment bed. In these simulations, the Navier-Stokes flow around each particle and within the pore spaces of the sediment bed is resolved by means of an immersed boundary method, with the particle-particle interactions being taken into account via a detailed collision model.

Highlights

Turbidity currents are particle-laden flows in the ocean that are driven by gravity (Meiburg and Kneller 2010)
The modeling of dilute, non-eroding turbidity currents has reached a mature level, as evidenced by the fact that high-resolution simulations have been able to reproduce many of the observations made in laboratory experiments (e.g., Nasr-Azadani et al 2013)
We are able to account for some topographical complexity via the immersed boundary method

Summary

Introduction

Turbidity currents are particle-laden flows in the ocean that are driven by gravity (Meiburg and Kneller 2010). Particle concentrations are usually sufficiently low far away from the sediment bed so that particle-particle interactions play a small or negligible role throughout most of the body of the current. In this region, the Boussinesq approximation of the Navier-Stokes equations, in conjunction with a continuum formulation for the sediment concentration, is well-suited to capture the dynamics of the flow. Near the sediment bed particle concentrations can be very high, which can potentially result in complex non-Newtonian behavior, hindered settling, and other effects. We describe the above two different simulation approaches, along with representative results, which open up a path towards multiscale flow simulations via the μ(I) rheology (Cassar et al 2005; Boyer et al 2011; Aussillous et al 2013)

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