Scale-Dependent Dispersion and its Uncertainty in Spatially Heterogeneous Flows
Felipe de Barros
Sonny Astani Department of Civil and Environmental Engineering
University of Southern California
Modeling solute transport behavior in large-scale heterogeneous porous formations require, in general, substantial computational burden. Additional challenges rise from the fact that the subsurface formation is usually characterized over a coarse measurement network that captures large-scale variability of the flow field. Due to computational and sampling constraints, solute transport models tend to adopt coarse numerical grid blocks. However, neglecting the subscale flow fluctuations that are wiped out by homogenization can lead to inaccurate representation of dispersive mass fluxes which have an impact on contaminant site management and risk analysis. In this talk, I will present a stochastic modeling framework to compute upscaled dispersion coefficients that incorporates the high frequency variability that is filtered out by homogenization and the uncertainty associated with the dispersive flux under non-ergodic transport conditions. Analytical and semi-analytical expressions for the temporal evolution of the mean and variance of the block-scale dispersion tensor are derived. These quantities provide information regarding the mixing efficiency and the ergodicity of the transport process. Results show the importance of the initial scale of the solute body, the block-scale and local-scale dispersion in controlling the uncertainty of the solute cloud’s dispersive behavior.
About the Speaker:
Dr. Felipe de Barros is an Assistant Professor in the Sonny Astani Department of Civil and Environmental Engineering at the University of Southern California (USC). Dr. de Barros has earned his PhD in the Department of Civil and Environmental Engineering at the University of California, Berkeley. He also holds an Engineering Degree and MS in Mechanical Engineering from the Federal University of Rio de Janeiro (Brazil). After the completion of the PhD at UC Berkeley, Dr. Felipe de Barros worked as a post-doctorate research fellow at the University of Stuttgart (Germany) and the Polytechnic University of Catalonia (Spain). Dr. de Barros has published 48 papers in peer-reviewed journals. He has served as a reviewer for the top journals in field of water resources and fluid mechanics. He is currently an Associate Editor for Water Resources Research, Journal of Hydrology and Hydrological Sciences Journal.
Prof. de Barros is the recipient of a NSF CAREER Award and the 2016 Editor's Citation for Excellence in Refereeing (Water Resources Research, AGU). Dr. de Barros’ main expertise is in stochastic hydrogeology and environmental fluid mechanics. His research interests include flow and transport in heterogeneous porous media, stochastic methods and human health risk.