COLLABORATIVE RESEARCH: The statistical mechanics of bed load sediment transport: Scaling particle motion to fluvial form

Project: Research project

Project Details


This Accomplishment-Based Renewal proposal is aimed at advancing key topics in sediment transport
based on insights and lessons we have learned from our continuing efforts to understand the statistical
mechanics of bed load transport. Our interrelated objectives for this proposed four-year project are to
elaborate the significance and consequences of patchy, rarefied transport conditions, and to examine
applications of our formulations of transport to streambed dynamics.
Intellectual Merit:
Rarefied transport conditions: We propose to pursue theoretical and experimental work involving gravelbed
flumes to illustrate: that particle motions locally represent samples drawn from ensemble
distributions; that the timescales of convergence to ensemble conditions depend on scale and transport
intensity; that there is an expected variability in these quantities (and in the flux and its divergence) about
the ensemble conditions; and that with convergence the averaged conditions match the ensemble
behavior, including varying equilibrium streambed configurations.
Beform dynamics: We propose to pursue numerical and experimental work using gravel-bed flumes to
illustrate both the kinematic and dynamic theoretical basis for the generation of bedforms, and how the
fundamental lengthscales in this problem are determined by the probability distributions of particle
motions. We also are aimed at parameterizing our statistical mechanical theory for the case of alternate
bar formation, thus providing the basis for further channel-scale morphodynamics problems in which
patchy, rarefied transport conditions exist.
Broader Impacts:
Continuing from our previous project, the broader impacts of the project are centered on: (i) elaborating a
novel framework for meshing ideas from statistical mechanics with experimental and computational
work, with the aim of growing this style of analysis in treatments of sediment transport; (ii) a
collaborative structure of student and postdoctoral education, capitalizing on key strengths at Vanderbilt
University, Arizona State University and the University of British Columbia, that will greatly enrich the
intellectual experiences of all participants; (iii) developing compelling teaching tools deriving from
visualizations of experiments and numerical simulations; and (iv) providing one-of-a-kind data sets to the
science community.
Two graduate students supported during this four-year project will gain a solid foundation in fluid
mechanics and transport phenomena relevant to Earth-surface systems as well as other geoscience and
engineering fields. Postdoctoral scholars similarly will have an opportunity to gain depth and experience
in the study of sediment transport phenomena. In addition, several undergraduate students will be
substantively involved, leading to senior thesis projects. Compelling images and videos of particle
transport and turbulence will be generated during the project, and will be made accessible to the science
community and the public via web pages and YouTube.
Much of the probabilistic framework we are pursuing in relation to transport in rivers --- both its
conceptual and technical elements --- is identical to the framework that we are using to clarify
ingredients and implications of nonlocal versus local transport on hillslopes. This commonality in
conceptual and technical elements therefore represents an important opportunity to explore connections in
our descriptions of transport in these different settings --- one involving relatively slow dynamics
(hillslopes) and the other involving relatively fast dynamics (rivers) --- with an eye toward generalizing
our descriptions of sediment particle transport across scales, including the behavior of tracer particles and
particle-borne substances on hillslopes as well as in rivers.
Effective start/end date8/1/177/31/22


  • National Science Foundation (NSF): $455,206.00


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