Sharpshooter Droplet Dynamics: Drop on Plate Experiments and CFD Simulations Part 2 of 3

Original video: https://youtu.be/0iJXAdjgzz8 Food consumption and waste elimination are vital functions for living systems. Although how feeding impacts animal form and function has been studied for more than a century since Darwin, how its obligate partner, excretion, controls and constrains animal behavior, size, and energetics remains largely unexplored. Here we study millimeter-scale sharpshooter insects (Cicadellidae) that feed exclusively on a plant’s xylem sap, a nutrient-deficit source (95% water). To eliminate their high-volume excreta, these insects exploit droplet superpropulsion, a phenomenon in which an elastic projectile can achieve higher velocity than the underlying actuator through temporal tuning. We combine coupled-oscillator models, computational fluid dynamics, and biophysical experiments to show that these insects temporally tune the frequency of their anal stylus to the Rayleigh frequency of their surface tension-dominated elastic drops as a single-shot resonance mechanism. Our model predicts that for these tiny insects, the superpropulsion of droplets is energetically cheaper than forming jets, enabling them to survive on an extreme energy-constrained xylem-sap diet. The principles and limits of superpropulsion outlined here can inform designs of energy-efficient self-cleaning structures and soft engines to generate ballistic motions.

This video continues our exploration of sharpshooter insect droplet ejection, focusing on laboratory experiments and computational modeling. We present:

(a) Tracking of droplet and plate movement during drop-on-plate experiments.

(b) Computational Fluid Dynamic (CFD) simulations of 1 mm droplets on a vibrating plate, examining the effect of variable frequencies (constant contact angle of ∼ 180◦).

(c) CFD simulations of 1 mm droplets on a vibrating plate, investigating the impact of variable contact angles (constant frequency of 100 Hz).

This part delves into the fluid dynamics of droplet ejection and its interaction with surfaces, combining experimental observations with computational analysis.

Watch part 1: https://youtu.be/Vg3pX08UUW0

Watch part 3: https://youtu.be/IEy9SG34B1g

Keywords: Drop-On-Plate Experiments, CFD Simulations, Tracking, Centroid, Droplet, Plate, Vibrating Plate, Contact Angle, Sharpshooter Insect, Droplet Ejection, Fluid Dynamics.

Citation:

Challita, E.J., Sehgal, P., Krugner, R. et al. Droplet superpropulsion in an energetically constrained insect. Nat Commun 14, 860 (2023). https://doi.org/10.1038/s41467-023-36376-5

Published on: 28 February 2023

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