All organisms interface with air or water. Their ability to breathe, photosynthesize, move, and feed is linked directly to how they interact with the fluid around them. I work to uncover the adaptations that allow organisms to thrive in a vast array of fluid flows, and understand the mechanisms that are at the root of these complex processes.

Low-Reynolds Number Flow of Microscopic Organisms

Protists are a significant part of the Earth’s ecosystem. They are responsible for carbon sequestration and water filtration, and play a vital role in aquatic food webs. Discovering how they move, feed, and thrive in water is essential to our understanding of their role in the ecosystem.

Vorticella feeding (source unknown).

At this very small scale, protists experience water in a very different way from larger organisms. Rather than moving easily through water like a fish, protists experience fluid that behaves much more like tree sap–thick, viscous, and difficult to move through. How do they do it? What adaptations allow them to negotiate this highly viscous world?

I study Vorticella, a genus of sessile protists that use cilia to produce a toroidal eddy necessary for feeding. These Vorticella are ubiquitous, and live in virtually every aquatic environment. Despite this ubiquity, our understanding of their feeding mechanics is limited.

In the lab, we seek to quantify how Vorticella respond to changes in flow conditions in a 3-dimensional manner. Using traditional tomographic light microscopy and novel digital inline holography, we are able to visualize these protists in 3D over time as we experimentally manipulate flow characteristics like velocity and oscillatory period. Our works aims to uncover how Vorticella accesses food in such a viscous environment. This empirical work will allow us to inform new ecosystem models of carbon uptake, improve water treatment facilities, and provide new insights for bio-inspired microfluidics research.

Physics of Splash-Cups

Ombrohydrochory, the dispersal of seeds via raindrops, is an adaptation that has evolved separately multiple groups within plants, fungi and lichens. In organisms that exhibit this splash-cup physiology, raindrops fall onto the cup and launch seeds, spores, or gemmae up to two meters away from the plant. It’s thought that this type of dispersal minimizes competition between offspring and parent while simultaneously ensuring the offspring have access to key microhabitat.

A raindrop launching gemmae (source unknown).

The physics of splash-cups is multivariate. Surface tension, surface wettability, ballistics, fluid dynamics and biology all contribute to the “launch” of a seed, spore, or gemma.

We study how these variables influence launch distance and use these models to inform biomimetic ink jet printing systems and piezoelectrics.

Avian Biomechanics and Aerodynamics

Birds are incredible flyers. They are nearly silent, extremely efficient, and can perform remarkable aerobatic maneuvers. Planes are poor performers by comparison in all categories but speed.

What makes birds so remarkable? One answer to this question is that birds can actively and passively morph in response to changes in aerial flow condition. Birds can modify their wing shape on a per-wingbeat basis. Additionally, their feathers are highly tuned to passively respond without any input from the bird.

(A feather deflecting at various speeds, plotted in MATLAB.)

I study these small but significant aspects of avian locomotion. How does wing morphing affect aerodynamics? How does feather bending influence local flow? And, how can we use these findings to improve existing aircraft technology?

My research aims to use birds as a model for next-generation aircraft that utilize passive and active wing morphing to improve efficiency, mitigate turbulence, and enhance safety.