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Dynamics of evaporating, interconnected droplets
Chenyang Ren1,2, Sri Ganesh Subramanian1,2, Shresht Jain1,2
1Manchester Centre for Nonlinear Dynamics, The University of Manchester, Manchester, M13 9PL, UK. anne.juel@manchester.ac.uk.
Soft Matter
|November 7, 2025
Summary
Fluid exchange between connected, evaporating droplets is driven by pressure differences. Droplet shape changes during evaporation can reverse this flow, a phenomenon explained by symmetry breaking and pitchfork bifurcation.
Area of Science:
- Fluid dynamics
- Thermodynamics
- Surface science
Background:
- Sessile droplets connected by microchannels are open to the atmosphere, allowing evaporation.
- Fluid exchange between droplets is influenced by hydrostatic and Laplace pressures.
- Evaporation alters droplet volume and shape, impacting fluid transport.
Purpose of the Study:
- To investigate the dynamics of fluid exchange between two connected, evaporating sessile droplets.
- To understand the role of pressure differences and shape changes in driving and reversing flow.
- To analyze the underlying mechanisms, including bifurcations, governing droplet interaction.
Main Methods:
- Experimental observation of sessile droplet pairs connected by microchannels.
- Analysis of fluid flow driven by hydrostatic and Laplace pressure differences.
- Stability analysis to identify bifurcations in flow dynamics.
- Investigation of droplet shape evolution during evaporation.
Main Results:
- Fluid exchange occurs via pumping flow driven by pressure gradients.
- Larger droplets typically feed smaller ones with unidirectional flow when contact areas are equal.
- Unequal contact areas can lead to flow reversal due to droplet shape switching.
- The flow dynamics are governed by a supercritical pitchfork bifurcation.
Conclusions:
- Evaporation-driven flow in connected droplets is governed by pressure differences and shape dynamics.
- Symmetry breaking, through unequal contact areas, induces flow reversal.
- The system transitions through quasi-stationary states determined by volume loss.
- Pitchfork bifurcation explains the observed flow dynamics and reversals.
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