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Mimicking wettability alterations using temperature gradients for water nanodroplets
Chirodeep Bakli1, Sree Hari P D, Suman Chakraborty
1Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupanagar 140001, India.
Nanoscale
|August 19, 2017
Summary
Pure water droplets can exhibit inverse Marangoni effect, moving to hotter areas against typical behavior. This finding, driven by wettability and temperature, has implications for efficient electronic chip cooling.
Area of Science:
- Fluid dynamics
- Surface science
- Materials science
Background:
- The Marangoni effect describes fluid movement from hot to cold regions due to surface tension gradients.
- Typically, surface tension decreases with temperature, driving this phenomenon in pure liquids like water.
- Existing understanding suggests the inverse Marangoni effect is limited to fluid mixtures.
Purpose of the Study:
- To investigate the coupled influence of wettability and temperature gradients on sessile droplet dynamics.
- To explore the feasibility of the inverse Marangoni effect in pure water under specific conditions.
- To understand the role of temperature-dependent surface tension and wetting parameters.
Main Methods:
- Utilizing molecular dynamics simulations to track the three-phase contact line evolution.
- Simultaneously analyzing droplet dynamics during evaporation and molecular diffusion.
- Examining sessile droplets on surfaces with varying wettabilities under temperature gradients.
Main Results:
- Demonstrated the inverse Marangoni effect in pure water, challenging previous assumptions.
- Showcased that droplet behavior is influenced by the interplay of wettability and temperature gradients.
- Identified conditions where droplets move towards hotter regions, defying the conventional Marangoni flow.
Conclusions:
- The inverse Marangoni effect is achievable in pure water at micro-scales, contrary to established theories.
- Tuning surface characteristics and Marangoni forces allows for controlled droplet transport.
- Findings offer potential for enhanced thermal management in electronic chip cooling through passive droplet manipulation.
