Collaborative Research: Sloshing liquid decontamination of compliant surfaces

University Of Tennessee Knoxville, Knoxville TN

Investigators

Abstract

The decontamination of remote surfaces is challenging, particularly when the accumulation of external matter hinders these surfaces’ dynamic function. An example of such surfaces is the small, flexible wings on flapping-wing robots that are beginning to approach the scale of natural insects. Removing liquid contaminants from these surfaces using vibration presents an opportunity for autonomous cleaning and drying. However, at these scales, the motion of the sloshing liquid contaminants and the flexible surfaces on which they rest are coupled—the deformation of one influences the other. Therefore, the principal aim of this project is to provide a deep understanding of how the motion of a surface impacts the motion and ejection of a liquid drop. This project will provide a foundation by which to adapt self-decontamination strategies to other surfaces vulnerable to droplets, such as those in food preparation and healthcare. This project also encompasses outreach activities to local high school students via science fair project mentoring and research opportunities in the PIs’ labs. The objective of this project is to reveal the physics of sloshing liquid contaminates and ejection from surfaces in which the fluid and surface motions are highly coupled. This tightly integrated experimental, theoretical, and numerical study will answer questions in highly interdependent fluid-structure interaction. This project mates two elementary systems—a cantilever and a fluid drop – to form a dynamically complex system. Driving the cantilever base causes it to bend and the drop to slosh and/or slide, and the substrate dynamically responds in turn to drop motion. High-speed videography and precisely controlled vibratory input will enable the characterization of drop motion and ejection events in which the solid substrate can exhibit a range of curvatures and accelerations throughout the vibration cycle. Conventional cantilever and elastica dynamics will be augmented with inertia-related non-conservative fluid forces to quantify dissipation, drop coherence, and fluid removal in these non-stationary processes. Numerics will permit the synthesis of coupled fluid- and solid-governing equations to determine the most effective excitation strategy for substrate decontamination. The ability to self-decontaminate adds a new dimension to the multi-functionality provided by flexible wings and will be critical to the functionality of surfaces vulnerable to chemicals, moisture, and biofilms. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.