Speaker
Description
Chemical and biological processes across natural and engineered porous media are often controlled by the mixing of solutes by fluid flow. Theoretical descriptions of mixing dynamics are currently largely limited to steady flows in fully or partially water-saturated environments. In contrast, in dynamic multiphase flows, fluid interfaces move in time, leading to persistent rearrangement of flow paths in time. The consequences of the resulting unsteady flow fields on solute mixing dynamics is generally unknown.
Here, we use experiments and numerical simulations to tackle this question. We find that dynamic two-phase flows lead to chaotic mixing, characterized by exponential stretching of fluid elements, which results in strongly enhanced mixing compared to steady single phase flows. In statstically steady flows, we show numerically that the time-asymptotic stretching rate is a non-monotonic function of the flow rate with a single maximum. We explain this behaviour by a mechanistic model based on basic multiphase flow characteristics, opening new perspectives to describing and modeling mixing and chemical reactions in a wide range systems.
| Country | Norway |
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| Acceptance of the Terms & Conditions | Click here to agree |
