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Droplet growth by coalescence in binary fluid mixtures
B E Burkhart1, P V Gopalkrishnan, S D Hudson
1Department of Macromolecular Science, Case Western Reserve University, Cleveland, Ohio 44106-7202, USA.
Physical Review Letters
|September 5, 2001
Summary
Shear flow in fluid mixtures affects how droplets merge. Droplet deformation at high shear rates influences droplet size distribution, preventing broadening and maintaining a narrow size range.
Area of Science:
- Fluid dynamics
- Colloid and interface science
Background:
- Understanding droplet behavior in immiscible mixtures is crucial for various industrial processes.
- Shear forces significantly impact droplet interactions and evolution within fluid systems.
Purpose of the Study:
- To investigate the evolution of drop-size distribution in immiscible fluid mixtures under defined shear histories.
- To determine the shear-induced coalescence efficiency (ε) and its dependence on capillary number (Ca).
Main Methods:
- In situ microscopy was employed to observe and analyze droplet behavior.
- The study focused on quantifying coalescence efficiency (ε) across different capillary numbers (Ca).
Main Results:
- Coalescence efficiency (ε) remained constant at low capillary numbers (Ca).
- At higher Ca values, ε decreased, aligning with theoretical models that consider droplet deformation.
- While coalescence generally broadens drop-size distribution, significant deformation of larger drops at high shear rates maintained a narrow distribution.
Conclusions:
- Droplet deformation plays a critical role in modulating coalescence efficiency and drop-size distribution under shear.
- The findings provide insights into the complex interplay between shear, deformation, and coalescence in fluid mixtures.