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Capillary-inertial colloidal catapults upon drop coalescence
Roger L Chavez1, Fangjie Liu1, James J Feng
1Department of Mechanical Engineering and Materials Science, Duke University , Durham, North Carolina 27708, USA.
Applied Physics Letters
|August 2, 2016
Summary
Drop coalescence on particles launches them from surfaces. This capillary-inertial catapult mechanism, requiring intermediate particle wettability, offers a novel way to remove contaminants and study biological launching.
Area of Science:
- Physics
- Materials Science
- Surface Science
Background:
- Surface energy release during drop coalescence drives droplet jumping on superhydrophobic surfaces.
- Jumping droplets can transport colloidal particles for self-cleaning applications.
Purpose of the Study:
- To investigate particle launching from solid surfaces driven by drop coalescence.
- To explore the mechanism of self-propelled particle ejection via capillary-inertial forces.
Main Methods:
- Studied drop coalescence on spherical particles with varying wettability.
- Analyzed momentum transfer from the liquid drop to the particle during coalescence.
- Investigated the relationship between drop size, particle properties, and launching velocity.
Main Results:
- Drop coalescence on a particle can induce self-propelled launching from any solid surface.
- Intermediate particle wettability is crucial for efficient momentum transfer.
- Launching velocity scales with capillary-inertial velocity and liquid mass fraction.
Conclusions:
- Drop coalescence on particles provides a novel capillary-inertial catapult mechanism.
- This phenomenon offers an alternative to self-cleaning by removing colloidal contaminants.
- The particle launching system serves as a model for studying biological ballistospore ejection.
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