Title: Multiphase Flow in Granular Media: How Pore-scale Heterogeneity Plays a Role
Abstract: As a typical heterogeneous porous material, granular media include everything from sand on the beach to flour and salt on our dining table. Various forms of heterogeneity can be observed in nature and synthetic materials and are shown to determine multiphase interactions in the pore scale. In this talk, we will discuss the combined effects of wettability and structural heterogeneities, with a special emphasis on materials with hierarchical structures, such as electrode materials in batteries, fibrous membranes in PEM fuel cells, and fractured rocks in geothermal extraction, which are generally composed of two components with distinct characteristic length scales. To this end, we implemented numerical models to capture the interface dynamics and to model the fluid displacement processes in porous media with variable pore structures and sizes. We emphasise the following aspects: how such heterogeneous pore structures influence fluid-fluid displacement under various wettability conditions, and most importantly, to what extent the immiscible fingering can be suppressed and controlled through tailored design of microstructure. To characterise fingering dynamics in heterogeneous porous media, we provide phase diagrams unifying the combined contributions from topological and morphological structures, wettability and flow conditions. The present study provides an alternative mechanism for controlling the temporal and spatial distribution of fluid phases within porous media for specific applications, e.g., increased drainage efficiency, or enhanced chemical reaction rate.
Presenter: Dr Yixiang Gan is an Associate Professor at School of Civil Engineering, The University of Sydney (USYD), and his research is on mechanics of materials, with a focus on multiscale modelling connecting the microstructure of heterogeneous media to material performance. He received the Dr.-Ing degree (with summa cum laude) from Karlsruhe Institute of Technology (KIT), Germany, in 2008. From 2009 to 2010, he continued worked at KIT as a research scientist on several European projects on nuclear fusion to develop predictive and design tools for energy materials. In 2010, he joined USYD, first as a Postdoctoral fellow, then Lecturer, Senior Lecturer and A/Prof. Since he joined USYD in 2010, he has secured $2.7M competitive research funding and published over 120 journal papers. His current research interests include mechanics of granular and porous media, multiphase flow, mechanics of interfaces, heat and electrical conduction, and carbon geo-sequestration.