Visualizing Fluid Physics of Microswimmers

Microscopic swimming organisms must generate forces that result in fluid flows to facilitate their motion and feeding. Studying the flow physics of swimming microorganisms is important to have a better understanding of their thermodynamics and interactions with their environment. Therefore, we developed an analysis based on the visualization of fluid flow using the flowtrace algorithm in ImageJ/Fiji. This allows us to quantify universal fluid flow patterns generated by a variety of organisms. So far, we observed that organisms generate vortices via cilial beating. The average velocity of the vortex exhibited a characteristic decay with distance from the cilia. Additionally, in organisms that vary in size by nearly 10 times, we found that the ratio of vortex size to cilia length is conserved, with a value of 5.00 ±0.86 (mean ±SD). This observation suggests the underlying flow physics may follow a scaling behavior for organisms of different sizes as they generate vortices for feeding.
Keywords: Microswimmers, fluid physics, microorganisms, feeding, thermodynamics, and vortex.