Mechanical and Civil Engineering Seminar

Mechanical and Civil Engineering Seminar Series

Title: Flow, transport, and mixing limited processes in confined & heterogeneous media

Abstract: Natural soils are host to a high density and diversity of substances, suspensions and microorganisms, and even deep-earth porous rocks provide a habitat for active microbial communities. In these environments, transport by disordered flows is relevant for a broad range of natural and engineered processes, from biochemical cycling to remineralization, bioremediation and filtration. A key property of most porous systems is the underlying heterogeneity that may occur due to non-uniformity in size or shape of the constitutive grains. Such physical heterogeneity controls transport and mixing of solutes driving geo-chemical kinetics and colloidal/bacterial deposition and filtration. The complexity that rises from the coupling of such microscopic processes makes predictions based on rates measured under homogenized, well-mixed, conditions different by orders of magnitudes from field observations. We use numerical methods and laboratory experiments (based on micro fluidics and time-lapse video-microscopy) to investigate microscopic processes (as flow, mixing, microbial transport and growth) that take place within the confined space of heterogeneously distributed pores. While observing these microscopic processes, we also monitor their macroscopic consequences, including deposition profiles, breakthrough curves, reaction kinetics and biomass growth. Based on such multi-scale observations, we build new theoretical models, that we feed with measured parameters, to unravel the link between microscopic-scale processes and their macroscopic consequences.

Bio: I am physicist and received a Master from the University of Florence (Italy) in Statistical Mechanics and a PhD in Earth Sciences from the University of Rennes 1 (France), where I studied mixing and reactions in porous media. While I was a postdoctoral fellow at MIT (Boston, U.S. within the group of prof. Ruben Juanes), I learned microfluidics and video-microscopy that I use to develop novel experiments for porous media investigation.

Since 2015, I have been a professor at the Institute of Earth Sciences (ISTE) of the University of Lausanne (UNIL). I am interested in the physics of flow and mixing-driven processes in confined micro-structures, like filters or soil, with particular attention to their coupling with biological activities. In my group we combine theoretical/numerical approaches to microfluidics experiments to visualize and quantify small scale processes in confined flows in the spirit of modelling their larger scale consequences (upscaling) on reactive transport and filtration phenomena. For more information visit, www.pietrodeanna.org.

NOTE: At this time, in-person Mechanical and Civil Engineering Lectures are open to all Caltech students/staff/faculty/visitors.