A touch of non-linearity: mesoscale swimmers and active matter in fluids

40 mins 41 secs,  155.29 MB,  iPod Video  480x270,  29.97 fps,  44100 Hz,  521.15 kbits/sec
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Description: Klotsa, D
Wednesday 15th May 2019 - 09:40 to 10:20
 
Created: 2019-05-16 13:09
Collection: The mathematical design of new materials
Publisher: Isaac Newton Institute
Copyright: Klotsa, D
Language: eng (English)
Distribution: World     (downloadable)
Explicit content: No
Aspect Ratio: 16:9
Screencast: No
Bumper: UCS Default
Trailer: UCS Default
 
Abstract: Living matter, such as biological tissue, can be seen as a nonequilibrium hierarchical assembly of assemblies of smaller and smaller active components, where energy is consumed at many scales. The functionality and versatility of such living or “active-matter” systems render it a promising candidate in a discussion on the optimal design of soft matter. While many active-matter systems reside in fluids (solution, blood, ocean, air), so far, studies that include hydrodynamic interactions have focussed on microscopic scales in Stokes flows, where the active particles are <100μm and the Reynolds number, Re <<1. At those microscopic scales viscosity dominates and inertia can be neglected. However, what happens as swimmers slightly increase in size (say ~0.1mm-100cm) or as they form larger aggregates and swarms? The system then enters the intermediate Reynolds regime where both inertia and viscosity play a role, and where nonlinearities in the fluid are introduced. In this talk, I will present a simple model swimmer used to understand the transition from Stokes to intermediate Reynolds numbers, first for a single swimmer, then for pairwise interactions and finally for collective behavior. We show that, even for a simple model, inertia can induce hydrodynamic interactions that generate novel phase behavior, steady states and transitions.
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