Pore-scale Investigation and the Applications in Energy and Environmental Sciences

Dr. Cheng Chen
Department of Earth & Atmospheric Sciences
Purdue University

ABSTRACT
High-energy, synchrotron-based X-ray difference micro-tomography (XDMT) was used to resolve the pore structure of a granular porous medium, as well as colloidal deposits within the pore space, with six-micron resolution. After processed by sophisticated image processing methods, the detailed structural information was used to define internal boundaries for three-dimensional lattice Boltzmann (LB) simulations of the effects of the colloidal deposits on pore-scale fluid flow and solute transport. Colloid accumulation was observed to be highly heterogeneous at the pore scale. The change in the geometry of the pore space greatly reduced the bulk permeability of the porous medium. The pore structure evolved to become increasingly complex over time. LB simulations of solute transport indicated that the temporal variation of pore structure enhanced anomalous diffusion behavior. In addition, a coupled multiphase LB model was used to simulate the dissolution of immiscible liquid droplets in another liquid during the rising process resulting from buoyancy. When more than two identical droplets rose simultaneously in a close proximity, the average terminal rise velocity was lower than that of a single droplet with the same size, because of the mutual resistant interactions. The Damkohler (Da) and Peclet (Pe) numbers were varied to investigate the coupling between droplet size, flow field, dissolution at the interface, and solute transport. By studying the coupling between Da and Pe, we qualitatively proposed to construct a Da-Pe phase plane, and found the interface dividing the plane into region 1 and 2. Region 1 was the collection of points where it was favorable to break down the droplet into as many small ones as possible in order to accelerate dissolution, while region 2 was the collection of points where it was favorable to keep the droplet in a single one for the same purpose.

BIO
Dr. Cheng Chen was born in China. He received his B.S. degree in Hydraulic Engineering at Tsinghua University, China, and Ph.D. in Civil and Environmental Engineering at Northwestern University. He is currently a Postdoctoral Research Associate at the Department of Earth & Atmospheric Sciences, Purdue University. His research interests include geological CO2 sequestration, colloid and contaminant transport in groundwater, and stream-subsurface water interaction and transport processes.