Chaos and irreversibility of a flexible filament in periodically driven Stokes flow

Agrawal, Vipin, 1994- (author): Stockholms universitet,Nordiska institutet för teoretisk fysik (Nordita),Fysikum,Nordita SU; Stockholm Univ, Roslagstullsbacken 23, S-10691 Stockholm, Sweden.;Stockholm Univ, Dept Phys, S-10691 Stockholm, Sweden.

Mitra, Dhrubaditya (author): Stockholms universitet,KTH,Nordic Institute for Theoretical Physics NORDITA,Nordiska institutet för teoretisk fysik (Nordita)

(creator_code:org_t)

American Physical Society (APS), 2022
2022
English.
In: Physical review. E. - : American Physical Society (APS). - 2470-0045 .- 2470-0053. ; 106:2

Related links:: https://doi.org/10.1...; show more...; https://urn.kb.se/re...; https://doi.org/10.1...; https://urn.kb.se/re...; show less...

Abstract Subject headings

The flow of Newtonian fluid at low Reynolds number is, in general, regular and time-reversible due to absence of nonlinear effects. For example, if the fluid is sheared by its boundary motion that is subsequently reversed, then all the fluid elements return to their initial positions. Consequently, mixing in microchannels happens solely due to molecular diffusion and is very slow. Here, we show, numerically, that the introduction of a single, freely floating, flexible filament in a time-periodic linear shear flow can break reversibility and give rise to chaos due to elastic nonlinearities, if the bending rigidity of the filament is within a carefully chosen range. Within this range, not only the shape of the filament is spatiotemporally chaotic, but also the flow is an efficient mixer. Overall, we find five dynamical phases: the shape of a stiff filament is time-invariant-either straight or buckled; it undergoes a period-two bifurcation as the filament is made softer; becomes spatiotemporally chaotic for even softer filaments but, surprisingly, the chaos is suppressed if bending rigidity is decreased further.

About the subject

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