Onsager-symmetry obeyed in athermal mesoscopic systems: Two-phase flow in porous media
Peer reviewed, Journal article
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Original versionFrontiers in Physics. 2020, 8 . 10.3389/fphy.2020.00060
We compute the fluid flow time correlation functions of incompressible, immiscible two-phase flow in porous media using a 2D network model. Given a properly chosen representative elementary volume, the flow rate distributions are Gaussian, and the integrals of time correlation functions of the flows are found to converge to a finite value. The integrated cross-correlations become symmetric, obeying Onsager's reciprocal relations. These findings support the proposal of a non-equilibrium thermodynamic description for two-phase flow in porous media.