Speaker
Description
Fluids involved in industrial, geological and biological media are often characterized by non-Newtonian rheologies. Examples are blood flow in microvascular networks, and the flow of polymer solutions or slurries in enhanced oil recovery, groundwater remediation and geothermal energy production. Spatial heterogeneity in the physical medium properties lead to scale effects in the flow and dispersion processes that manifest in non-Fickian transport and non-Darcian flow behaviors. Despite their importance, there is significant lack of understanding of the fundamental physics resulting from the interaction of flow nonlinearity and complex medium structure. To close this gap, we analyze the flow and dispersion of shear-thinning and dilatant fluids in heterogeneous networks of different topologies. The flow fields are characterized statistically in terms of the distribution of volumetric flow rates and Eulerian and Lagrangian flow velocities and their correlation properties. The relation between structure and flow is analyzed using conditional statistics and the percolation characteristic of the underlying networks, which informs the quantification of large scale flow behaviors in terms of generalized (non-linear) Darcy laws (average flow) and flow statistics. To probe the dispersion of a passive scalar, we focus on particle breakthrough curves and displacement statistics. We observe broad distributions of particle arrival times and non-linear evolution of the displacement variance, which are manifestations of memory processes that occur due to broadly distributed flow velocities and mass transfer rates. Using a continuous time random walk approach, these behaviors are linked to the Eulerian flow statistics and medium structure.
| Country | Spain |
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