Levich Institute Seminar Announcement, 04/28/2015
Steinman Hall, Room #312
(Chemical Engineering Conference Room)
Professor Tian-Jian (Tom) Hsu
University of Delaware
Civil and Environmental Engineering
"Understanding Coastal Sediment Transport through Turbulence-Resolving Numerical Simulations"
One of the most intriguing issues in fine sediment (mud) transport, including turbidity currents, current driven resuspension, is that the presence of sediments may significantly attenuate flow turbulence. Depending on the level of turbulence suppression, it may lead to the formation of lutocline (a sharp negative gradient of sediment concentration) which further encourages gravity flow; or it may cause catastrophic collapse of turbulence and deposition. Due to very small Stokes number associated with fine sediment, equilibrium approximation is used to simplify the Eulerian two-phase flow equations. Through idealized turbulence-resolving simulations with fine sediment load prescribed in the domain, our recent studies reveal that the transition of these flow modes also exist in the wave bottom boundary layer. This talk further reports our most recent investigation on how the resuspension/deposition mechanisms, specifically the critical shear stress of erosion can dictate the transport mode. Toward the end of the talk, the speaker will also discuss ongoing study to develop a turbulence-resolving simulation model for sand transport (moderate Stokes number) based on the Eulerian two-phase flow formulation. Preliminary results on the occurrence of wave-like instability and billows near the bed subject to large horizontal pressure gradient are presented.
BRIEF ACADEMIC/EMPLOYMENT HISTORY
RECENT RESEARCH INTERESTS
Environmental Fluid Mechanics, Sediment Transport, Coastal Oceanography/Engineering.