History-independence of steady-state in simultaneous two-phase flow through porous media

TL;DR

This study investigates whether the steady-state of simultaneous two-phase flow in porous media depends on initial conditions, finding that it does not, unlike transient behaviors, through extensive experiments and simulations.

Contribution

It demonstrates that steady-state two-phase flow in porous media is independent of initial conditions, contrasting with transient flow dependence, based on combined experimental and numerical analysis.

Findings

Steady-state flow is independent of initial conditions.

Transient behavior depends on history and initial setup.

Experimental and numerical results agree on history-independence.

Abstract

It is well known that the transient behavior during drainage or imbibition in multiphase flow in porous media strongly depends on the history and initial condition of the system. However, when the steady-state regime is reached and both drainage and imbibition take place at the pore level, the influence of the evolution history and initial preparation is an open question. Here, we present an extensive experimental and numerical work investigating the history dependence of simultaneous steady-state two-phase flow through porous media. Our experimental system consists of a Hele-Shaw cell filled with glass beads which we model numerically by a network of disordered pores transporting two immiscible fluids. From the measurements of global pressure evolution, histogram of saturation and cluster-size distributions, we find that when both phases are flowing through the porous medium, the steady state does not depend on the initial preparation of the system or on the way it has been reached.