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Microstructure response of concentrated suspensions to flow reversal
A A García1,2, Y L Roht3, I Ippolito4
1Universidad de Buenos Aires, Facultad de Ingeniería, Grupo de Medios Porosos, Paseo Colón 850, 1063, Buenos Aires, Argentina. aagarcia@fi.uba.ar.
The European Physical Journal. E, Soft Matter
|January 23, 2025
Summary
This study investigates dense particle suspensions under flow reversals. Particle migration and microstructure changes were observed, revealing flow dynamics and reorganization behaviors in non-Brownian suspensions.
Area of Science:
- Fluid dynamics
- Materials science
- Rheology
Background:
- Dense suspensions of non-Brownian particles exhibit complex behaviors under flow.
- Understanding particle migration and microstructure evolution is crucial for predicting suspension properties.
Purpose of the Study:
- To experimentally investigate the macroscopic and microstructure behavior of dense, neutrally buoyant, non-Brownian spherical particle suspensions.
- To characterize the quasi-steady state, particle migration, pair distribution, and dynamic rearrangements under periodic flow reversals.
Main Methods:
- Experimental study at macroscopic and microstructure scales.
- Tracking individual spherical particles in a dense suspension.
- Applying periodic flow reversals at a constant rate between parallel plates.
Main Results:
- Particle volume fraction increases from walls to center due to migration induced by nonuniform strain rate.
- Particle pair distribution shows fore-aft asymmetry with depletions in extensional quadrants.
- Relaxation time for reorganization increases from walls to center; accumulated strain for reorganization decreases with volume fraction.
Conclusions:
- Particle migration and microstructure evolution are key factors in dense suspension dynamics under flow reversals.
- The study highlights the complementary nature of microstructure and viscosity measurements in understanding suspension rheology.
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