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Head-On Collision of Dissimilar Viscosity Drops
Hiranya Deka1, Gautam Biswas2, Bhaskor Jyoti Bora3
1Department of Mechanical, Materials and Aerospace Engineering, Indian Institute of Technology Dharwad, Dharwad 580011, India.
Langmuir : the ACS Journal of Surfaces and Colloids
|May 26, 2023
Summary
Head-on liquid drop collisions with different viscosities show new outcomes beyond simple merging or separation. Viscosity contrast creates asymmetric flow, leading to encapsulation and crossing separation, not predicted by average viscosity alone.
Area of Science:
- Fluid Dynamics
- Interfacial Phenomena
- Multiphase Flow
Background:
- Head-on drop collisions are governed by interfacial tension, viscosity, and inertia.
- Previous studies focused on identical drops, predicting coalescence or reflexive separation based on force magnitudes.
Purpose of the Study:
- To numerically investigate head-on collisions of miscible liquid drops with dissimilar viscosities.
- To determine if average viscosity predicts collision outcomes for fluids with varying viscosity ratios.
Main Methods:
- Numerical simulations of head-on drop collisions.
- Analysis of outcomes across a range of viscosity ratios and Weber numbers.
- Development of a phase diagram based on simulation results.
Main Results:
- Average viscosity accurately predicts outcomes only for low viscosity ratios.
- High viscosity ratios lead to asymmetric flow, deviating from average viscosity predictions.
- Two novel outcomes, encapsulation and crossing separation, were identified due to viscosity contrast.
Conclusions:
- Viscosity contrast in drop collisions introduces complex asymmetric flow dynamics.
- The average viscosity is insufficient to predict collision outcomes when viscosity ratios are high.
- A phase diagram mapping collision outcomes based on viscosity ratio and Weber number was established.
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