Fluid turbulence is everywhere in the natural and engineered world: a complex tangle of vortices and eddies that span a wide range of length and time scales. However, from the point of view of objects and animals suspended in turbulence, this complexity is highly dependent on scale. Small, nearly-massless things are passive tracers, completely at the mercy of the surrounding flow; large, massive things can pass through even strong turbulence without being affected too much by it. In between, there is a continuum of spatiotemporal complexity where suspended matter is intermittently affected by turbulence. We will explore these intermediate scales and their physics, and discuss what they can teach us about both engineering and biology.
