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From plankton to plastics: Dynamics of active and passive particles in wave-driven flows

Event Type
Water Resources Engineering Science
1017 Civil and Environmental Engineering Building (Hydro)
wifi event
Mar 3, 2023   12:00 - 12:50 pm  
Dr. Nimish Pujara
Jennifer J Bishop
Originating Calendar
Water Resources Engineering and Science Seminars

Water waves are a ubiquitous feature in lakes and oceans. The same water columns also host a variety of small particles such as phytoplankton (small swimming photosynthetic organisms that are the basis of aquatic food webs) and plastic debris (an emerging pollutant that is widely found in natural water bodies). Here we consider how the motion of such particles is affected by wave-driven flows. Starting with particles whose dynamics are in the inertialess regime, we show how particle body shape, buoyancy, and swimming couple to the flow in small-amplitude sinusoidal waves to influence wave-averaged particle orientation, drift, and dispersion. We then consider the effects of particle inertia and fluid inertia for the specialised cases of negatively buoyant spheres and fibres. Finally, we consider the problem of particle beaching, which is relevant to marine debris pollution, and show that whether a particle is beached or not by a particular wave is controlled by a combination of the particle’s inertia and initial conditions.

Nimish Pujara was an undergraduate at Cambridge University and obtained his doctorate at Cornell University. After a postdoctoral position at UC Berkeley, he joined the Department of Civil and Environmental Engineering at University of Wisconsin – Madison as a faculty member. He now leads a group that pursues research in fluid mechanics with the aim of improving understanding of various environmental processes.

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