Linking scales of sediment dynamics from sand grains to the synoptic

Joe Calantoni, Naval Research Laboratory

In the Sediment Dynamics Section at the U.S. Naval Research Laboratory we perform basic and applied research focused on understanding seafloor, estuarine, and riverine sediments. We are motivated by the need to predict the dynamical properties of sediments. A multi-disciplinary team of scientists and engineers works in a collaborative environment to simulate, model and observe phenomena in both the laboratory and field at scales from the motions of individual sand grains immersed in fluid up to tens of kilometers and several days. Simulation and modeling efforts are focused on a new probabilistic paradigm to bridge the gap from grain scale physics to large-scale morpohdynamics. We propose to utilize a hierarchy of computationally intensive, high fidelity simulations to populate a probabilistic framework to make predictions across a range of cascading length and time scales. The success of our approach relies on rigorous validation of our high fidelity simulations using detailed laboratory and field measurements of fluid-particle turbulence at the scales of interest. Recent advances in optical imaging techniques have made it possible to make highly resolved three-dimensional measurements of fluid-particle turbulent interactions in the laboratory with spatial and temporal resolutions at or near the Kolmogorov scale. Work is ongoing to transition these technologies for use in the field. Synoptic field observational efforts are focused on combining remote sensing with in situ measurements to provide both validation for emerging predictive capabilities and optimization for data assimilation and boundary conditions for operational forecasting. We will present an overview of results from our modeling efforts along with relevant laboratory and field observations.