--> Abstract: High-Resolution Simulations of Gravity and Turbidity Currents, by Eckart Meiburg, Ben Kneller, Brendon Hall, Francois Blanchette, Vineet Birman, Moshe Strauss, Michael Glinsky, and Chris Lerch; #90078 (2008)

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High-Resolution Simulations of Gravity and Turbidity Currents

Eckart Meiburg1, Ben Kneller2, Brendon Hall1, Francois Blanchette1, Vineet Birman1, Moshe Strauss4, Michael Glinsky3, and Chris Lerch3
1Mechanical Engineering, UC Santa Barbara, Santa Barbara, CA
2Geology, University of Aberdeen, Aberdeen, United Kingdom
3BHP Billiton Petroleum, Houston, TX
4Physics, Nuclear Research Center Negev, Beer-Sheva, Israel

We will present high-resolution, Navier-Stokes based simulations of gravity and turbidity currents. The turbidity currents considered are driven by particles that are much smaller than the smallest length scales of the buoyancy-induced fluid motion. For the mathematical description of the particulate phase an Eulerian approach is employed.

We will discuss differences between two- and three-dimensional gravity current dynamics, along with the influence of slip and no-slip walls. Flow features due to large, non-Boussinesq density differences will be analyzed, and differences in the dynamics of the light and heavy fronts will be discussed. In the presence of a sloping bottom the early, constant front velocity phase is seen to give rise to a second phase characterized by the dynamics of horizontal layers accelerating past each other, similar to the classical analysis by Thorpe. Some effects due to stratification of the ambient will be discussed as well. Results will be shown regarding turbidity current flows in complex geometries, and the unsteady interaction of a gravity current with a submarine structure, such as a pipeline.

In the analysis of turbidity currents, special emphasis is placed on the sedimentation and resuspension of the particles, and on their feedback on the flow. Resuspension is modeled as a diffusive flux of particles through the bottom boundary. Time-dependent sedimentation profiles at the channel floor are presented which agree closely with available experimental data. The conditions under which turbidity currents may become self-sustaining through particle entrainment are investigated as a function of slope angle, current and particle size, and particle concentration.

 

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas