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From Single to Collective: Model Swimmers at Intermediate Reynolds Numbers.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	From Single to Collective: Model Swimmers at Intermediate Reynolds Numbers./
作者:	Dombrowski, Thomas John.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2021,
面頁冊數:	105 p.
附註:	Source: Dissertations Abstracts International, Volume: 82-12, Section: B.
Contained By:	Dissertations Abstracts International82-12B.
標題:	Physics. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28418498
ISBN:	9798515280222

From Single to Collective: Model Swimmers at Intermediate Reynolds Numbers.
Dombrowski, Thomas John.

From Single to Collective: Model Swimmers at Intermediate Reynolds Numbers. - Ann Arbor : ProQuest Dissertations & Theses, 2021 - 105 p.

Source: Dissertations Abstracts International, Volume: 82-12, Section: B.

Thesis (Ph.D.)--The University of North Carolina at Chapel Hill, 2021.

This item must not be sold to any third party vendors.

Biological and artificial swimmers exist across a broad range of length scales, spanning from micron-sized bacteria and self-propelled nanoparticles to large aquatic organisms and marine robots on the order of meters. Swimming can be categorized by the Reynolds number (Re) which characterizes the relative importance of inertial over viscous forces. Microscopic swimmers at low Re, where viscosity dominates, swim differently than high Re swimmers, where inertia dominates. Between the two extremes resides the intermediate Reynolds regime (Reint ≈ 0.1-1000), where both viscosity and inertia play a role. Mesoscopic organisms i.e. those that operate at intermediate Re are diverse both in size, ≈ 0.5 mm-50 cm, and in swimming mechanisms. Most prior studies on Reint motility have focused on the details of specific organisms. As a result, few general models exist and there is a lack of understanding regarding the unifying physical mechanisms that swimmers at Reint exhibit. In this dissertation, we use computational fluid dynamics to model and characterize mesoscale swimmers, examine their pairwise interactions, and ultimately build a framework to understand their collective behavior. We first show a simple model swimmer used to understand the transition from Stokes (Re = 0) to intermediate Reynolds numbers. Our swimmer is a dumbbell which consists of two unequal spheres that oscillate in antiphase generating nonlinear steady streaming flows. We show computationally that steady streaming flows enable the swimmer to propel itself and switch direction as Re increases. We quantify the transition in the swimming direction by collapsing my data on a critical Re and show that the transition in swimming direction corresponds to the reversal of the flows. From thousands of initial conditions, four stable pairs were identified, where the swimmers coordinated in-line or in-tandem. We investigated how the stable pairs' fluid flow fields evolved across Re and connected them to transitions in pair swimming behavior. The collective behavior of 122 swimmers transitions from in-line network-like connections to small, transient in-tandem clusters. Pairwise interactions were used to partly explain the collective behavior; however, limitations were discovered as many-body interactions such as triples were also identified.

ISBN: 9798515280222Subjects--Topical Terms:

516296
Physics.
Subjects--Index Terms:

Collective behavior

From Single to Collective: Model Swimmers at Intermediate Reynolds Numbers.
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245 1 0 $a From Single to Collective: Model Swimmers at Intermediate Reynolds Numbers.
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300 $a 105 p.
500 $a Source: Dissertations Abstracts International, Volume: 82-12, Section: B.
500 $a Advisor: Klotsa, Daphne.
502 $a Thesis (Ph.D.)--The University of North Carolina at Chapel Hill, 2021.
506 $a This item must not be sold to any third party vendors.
520 $a Biological and artificial swimmers exist across a broad range of length scales, spanning from micron-sized bacteria and self-propelled nanoparticles to large aquatic organisms and marine robots on the order of meters. Swimming can be categorized by the Reynolds number (Re) which characterizes the relative importance of inertial over viscous forces. Microscopic swimmers at low Re, where viscosity dominates, swim differently than high Re swimmers, where inertia dominates. Between the two extremes resides the intermediate Reynolds regime (Reint ≈ 0.1-1000), where both viscosity and inertia play a role. Mesoscopic organisms i.e. those that operate at intermediate Re are diverse both in size, ≈ 0.5 mm-50 cm, and in swimming mechanisms. Most prior studies on Reint motility have focused on the details of specific organisms. As a result, few general models exist and there is a lack of understanding regarding the unifying physical mechanisms that swimmers at Reint exhibit. In this dissertation, we use computational fluid dynamics to model and characterize mesoscale swimmers, examine their pairwise interactions, and ultimately build a framework to understand their collective behavior. We first show a simple model swimmer used to understand the transition from Stokes (Re = 0) to intermediate Reynolds numbers. Our swimmer is a dumbbell which consists of two unequal spheres that oscillate in antiphase generating nonlinear steady streaming flows. We show computationally that steady streaming flows enable the swimmer to propel itself and switch direction as Re increases. We quantify the transition in the swimming direction by collapsing my data on a critical Re and show that the transition in swimming direction corresponds to the reversal of the flows. From thousands of initial conditions, four stable pairs were identified, where the swimmers coordinated in-line or in-tandem. We investigated how the stable pairs' fluid flow fields evolved across Re and connected them to transitions in pair swimming behavior. The collective behavior of 122 swimmers transitions from in-line network-like connections to small, transient in-tandem clusters. Pairwise interactions were used to partly explain the collective behavior; however, limitations were discovered as many-body interactions such as triples were also identified.
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650 4 $a Biophysics. $3 518360
653 $a Collective behavior
653 $a Intermediate Reynolds number
653 $a Locomotion
653 $a Pair interactions
653 $a Swimming
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710 2 $a The University of North Carolina at Chapel Hill. $b Physics. $3 2103021
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