Pore-Scale Behavior of Darcy Flow in Static and Dynamic Porous Media

Pore-scale flow behavior is important in many areas of science and engineering that deal with porous media, including geophysics, hydrogeology, biophysics, and filtration. This numerical study shows that variable structures dependent on flow rate exist in dynamic porous media, which contradicts the Darcy permeability model. In spite of $m\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}p\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}c$ flow variations (tortuosity), the $m\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}p\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}c$ flow behavior (permeability) remains constant. The possibility of these variable structures (shown to be induced also by local pressure fluctuations) raises questions about the universality of constant-tortuosity models for Darcy flow, challenging our view of transport in porous media.