PoreLab is pleased to announce the next PoreLab Lecture. To join, please follow the link below the abstract or add this event to your calendar by opening the attached calendar ics-file.
When: Wednesday, April 7th, at 14:00 (Central Europe)
Where: zoom (see below)
Title: Hysteresis, memory and energy dissipation in fluid-fluid displacement in disordered media
Speaker: Ran Holtzman
Affiliation: Associate Professor at Coventry University, UK
Cyclic fluid-fluid displacements in disordered media feature hysteresis, multivaluedness, and memory properties in the pressure-saturation relationship. Quantitative understanding of the underlying pore-scale mechanisms and their extrapolation across scales constitutes a major challenge. We present an ab initio model of quasistatic displacements in a Hele-Shaw cell with random gap spacing. In contrast with the existing phenomenological approaches, all parameters in our model have a clear, identifiable physical meaning, allowing its rigorous validation against experimental and analytical data.
Our model provides the quantitative link between the microscopic capillary physics, spatially-extended collective events (Haines jumps), energy dissipation and large-scale hysteresis. We show that the accumulated dissipation along a cyclic pressure-saturation trajectory coincides with the area enclosed by the cycle. We find that the energy dissipated in individual Haines jumps between two consecutive equilibrium configurations (i) needs not to be proportional to the corresponding increase in saturation (avalanche size), (ii) spans many orders of magnitude, and (iii) can greatly exceed the work invested in driving the system between these configurations.
We show the dependence of dissipation on system properties such as the microstructural heterogeneity and gravity. Strikingly, we discover that hysteresis and energy dissipation can emerge from cooperative behavior between individually reversible capillary displacements. This contrasts the widely-used compartment models (Everett porous media; Preisach in ferromagnetism) which rely on the existence of a basic noninteracting hysteretic unit. Finally, we show that most of the dissipation in quasistatic displacements is due to irreversible release of elastic energy in Haines jumps rather than viscosity.
Join by H.323:
Meeting ID: 673 5647 1922
Fredrik K. Eriksen