Research Area 2.1: Fluid-Driven Sediment Transport: A first-principles approach joining geological observations and granular-fluid physics
Abstract
The technical objective of the proposed effort is to determine how grain-scale physics influences the mechanisms and rate of field-scale sediment transport. The proposed-effort seeks to achieve the stated technical objective using a combined approach involving (I) laboratory flume experiments, (2) numerical simulations, and (3) analysis of experimental and numerical results. For (I), a series of laboratory flume experiments will be performed in which the entrainment and bedload transport of ideal and natural sediment grains under controlled flow conditions and simple channel geometry will be studied. Experiments will be performed with uniformly sized spherical grains and sieved natural river sand subject to flow conditions ranging from the threshold of entrainment to the threshold of suspension. A clear-sided acrylic channel approximately Sm long, 30 cm wide and 50 cm deep will be supported by a frame that allows the channel to be tilted up to 5 degrees. Grain motion will be imaged from above and through one of the channel sidewalls with high-frame-rate digital cameras connected to a computer, and particle image velocimetry will be used to measure the fluid velocity field during each experiment. In (2), the grain-scale dynamics of sediment motion will be simulated using a discrete-particle plus Lattice-Boltzmann fluid method (LBM-DEM). The method tracks discrete particles interacting with each other through contact laws while mechanically coupled to a dynamic interstitial fluid. These numerical simulations will replicate the conditions in the flume experiments In addition to calculating initial grain motion and bedload sediment flux directly, the LBM-DEM simulations will include a large enough volume of grains that it will be possible to identify zones in which different regimes of granular behavior occur. In (3), the numerical model will be tested through comparison with laboratory flume experimental results and with published studies on bedload sediment transport. Validation efforts will be focused on determining if the LBM-DEM simulations accuratelly characterize the style and rate of grain entrainment and transport and identification of the necessary input and precision parameters for the LBM-DEM code to ensure that the simulations are a faithful representation of the corresponding flume cross-section.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 12, 2017
- Source ID
- W911NF1610440
Entities
People
- Ken Kamrin
Organizations
- Army Contracting Command
- Massachusetts Institute of Technology
- United States Army