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Shear banding in biphasic liquid-liquid systems.
Sergio Caserta1, Marino Simeone, Stefano Guido
1Dipartimento di Ingegneria chimica, Università di Napoli Federico II, Napoli 80125, Italy.
Physical Review Letters
|June 4, 2008
Summary
We report shear-induced banding in microconfined liquid-liquid systems, forming alternating droplet regions. This flow-driven phenomenon, observed at low viscosity ratios, reduces system viscosity, indicating microstructural evolution towards lower energy dissipation.
Area of Science:
- Fluid dynamics
- Soft matter physics
- Rheology
Background:
- Biphasic liquid-liquid systems exhibit complex flow behaviors.
- Microconfinement and shear flow can induce structural rearrangements.
- Understanding these phenomena is crucial for various industrial applications.
Purpose of the Study:
- To systematically investigate shear-induced banding in microconfined biphasic liquid-liquid systems.
- To determine the conditions under which banding occurs.
- To understand the relationship between banding and rheological properties.
Main Methods:
- Utilizing a parallel plate flow cell for microconfinement.
- Applying controlled shear rates to biphasic liquid-liquid systems.
- Conducting rheological measurements to analyze system viscosity.
Main Results:
- First systematic report of shear-induced banding in microconfined biphasic systems.
- Banding observed as alternating regions of high and low dispersed-phase droplet volume fraction.
- Phenomenon is flow-driven and gap-dependent, occurring at low viscosity ratios and specific shear rates.
- Band formation correlates with a decrease in system viscosity compared to homogeneous systems.
Conclusions:
- Shear-induced banding is a significant flow-driven phenomenon in microconfined biphasic systems.
- The observed viscosity reduction suggests microstructural evolution towards reduced viscous dissipation.
- Findings provide insights into the complex interplay between flow, confinement, and microstructure in soft matter systems.
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