"Using Chemical Potential and Gibbs Potential to Model Vapor Transport Through Partially Saturated Porous Media and As Boundary Conditions for Nanopores or Swelling Porous Media"

by Lynn Schreyer from Washington State University in STAG 113

Link  to AMC seminar. 

Abstract

The concept of a potential (e.g. chemical potential, Gibbs potential) in regards to modeling transport in porous media is not intuitive. Yet understanding it helps provide physical intuition and using it as a primary unknown can, in some cases, simplify the model. We will consider two examples:

(1) It is well known that water vapor transport in porous media is enhanced when the porous media is partially saturated with liquid water. Modeling vapor transport at the pore scale is traditionally done by considering pressures as the primary dependent variables, which then involves capturing contact angles and curvature. Here we show that by changing the dependent variable to relative humidity (or more generally chemical potential), a much simpler model can be developed and is conceptually easier to understand. Comparing analytical results with experimental data show that indeed, it is a reasonable model.

(2) When bulk fluid is in contact with a swelling porous media, membranes, or nanopores, it is often mistakenly assumed that pressure and/or concentration are continuous across the boundary. Here we show that it is the Gibbs potential or chemical potential that is continuous.

This talk is primarily based on the following papers

Pore-scale modeling of vapor transport in partially saturated capillary tube with variable area using chemical potential, Addassi, Schreyer, Johannesson, and Lin, Water Resources Research, 2016.

Macroscopic Flow Potentials in Swelling Porous Media, Schreyer-Bennethum, Transport in Porous Media, 2012.

Bio:

After obtaining a BS and MS in Mechanical Engineering, Lynn found her true home in Applied Mathematics, and obtained her PhD in 1994 from Purdue University (where she also became good friends with Malgo and Ralph). She then did a post doc in Agronomy at Purdue University before becoming a professor at University of Colorado Denver. In 2016 she moved to the Department of Mathematics and Statistics at Washington State University, where she now resides.

Lynn’s specialty is in modeling Multiphysics problems involving flow, transport, and deformation of porous materials. Her work has been used to model paper, drug-delivery polymers, movement of cilia in lungs, swelling clay soils, and wood. She is currently working on modeling the movement of ungulates (with Zach Hilliard), wave propagation through porous media, and carbon cycling.

Lynn has been the president of SIAM Geosciences, the program chair for InterPore 2012, Vice President for the SIAM Pacific Northwest Section (2020-2022), and co-chaired the SIAM Pacific Northwest Section biennial meeting that took place in 2022.