Stretching and folding sustain microscale chemical gradients in porous media

• DOI: 10.1073/pnas.2002858117
• Publication Date: 2020-05-29T00:25:41Z
• Authors: Joris Heyman; Daniel R. Lester; Régis Turuban; Yves Méheust; Tanguy Le Borgne
• Keywords: Microscale chemistry; Multiphase flow

Significance Porous media flows are central to environmental, industrial, and biological systems, where they transport molecules, particles, microorganisms trigger important biogeochemical reactions. There is increasing evidence that many of these processes highly sensitive chemical gradients below the pore-scale. However, it unknown how porous architectures control microscale concentration heterogeneities. Here, we provide high-resolution experimental images fully resolve three-dimensional pore-scale mixing dynamics. We show grain contacts folding fluid elements in pore space, which, addition stretching at stagnation points, leads exponential enhancement gradients. use insights derive a kinematic model linking rates geometry, opening perspectives for reactive modeling.