EAR-PF: The Mechanics of Turbulence and Sediment Transport: Physically-Based Numerical Modeling of Flow, Sediment and Bed Evolution in the Bedrock Canyons

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Dr. Laura V. Alvarez has been awarded an NSF Earth Sciences Postdoctoral Fellowship to carry out a research and education plan at the University of Oklahoma and Simon Fraser University. The proposed work will make substantial contributions to our capability to numerically understand and predict the physical phenomena that control sediment transport and morphodynamic evolution of river networks. Gains in the knowledge of the role played by macro-turbulence events in sediment dynamics will allow us to obtain a deeper understanding of what determines the geomorphologic changes and will lead to the development of more efficient models.This model can also serve to investigate to what extent information obtained from well-controlled experiments and numerical simulations conducted at laboratory scale can be used to understand the physics of sediment transport at larger scales and to provide predictions about river network changes. The fellow will engage education and outreach by developing a six-week summer course in fluvial modeling, integrating many of the proposed research experiments.Eddy resolving three-dimensional simulations combined with field and laboratory observations allow elucidation of key elements of fluid dynamics and sediment transport in fluvial environments. These models can resolve the time-dependent, energetically important, turbulent structures of the flow capturing the interactions between these eddies and the loose bed boundaries where sediment entrainment and deposition can occur. This research study proposes a compelling strategy for applying state-of-the-art computational fluid mechanics to the study of sediment transport and morphodynamic processes in fluvial systems. The main objective of the proposed research is the development and testing of a fully three-dimensional turbulence resolving model using Dettached Eddy Simulation techniques that can simulate turbulent flows under a broad range of spatial and temporal scales and their effect on sediment transport, entrainment and deposition and channel/river reach evolution. The numerical model will then be used to (1) understand the role played by the plunging flows, secondary flows and velocity inversions on sediment transport, entrainment and deposition in river reaches and (2) explain morphodynamic changes based on the dynamics of the macro-turbulence effects and velocity redistribution inside the river reach.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.