Active Brownian motion of emulsion droplets: coarsening dynamics at the interface and rotational diffusion

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dc.contributor.authorSchmitt, Max
dc.contributor.authorStark, Holger
dc.date.accessioned2017-09-01T08:04:38Z
dc.date.available2017-09-01T08:04:38Z
dc.date.issued2016
dc.description.abstractA micron-sized droplet of bromine water immersed in a surfactant-laden oil phase can swim (S. Thutupalli, R. Seemann, S. Herminghaus, New J. Phys. 13073021 (2011). The bromine reacts with the surfactant at the droplet interface and generates a surfactant mixture. It can spontaneously phase-separate due to solutocapillary Marangoni flow, which propels the droplet. We model the system by a diffusion-advection-reaction equation for the mixture order parameter at the interface including thermal noise and couple it to fluid flow. Going beyond previous work, we illustrate the coarsening dynamics of the surfactant mixture towards phase separation in the axisymmetric swimming state. Coarsening proceeds in two steps: an initially slow growth of domain size followed by a nearly ballistic regime. On larger time scales thermal fluctuations in the local surfactant composition initiates random changes in the swimming direction and the droplet performs a persistent random walk, as observed in experiments. Numerical solutions show that the rotational correlation time scales with the square of the inverse noise strength. We confirm this scaling by a perturbation theory for the fluctuations in the mixture order parameter and thereby identify the active emulsion droplet as an active Brownian particle.en
dc.identifier.eissn1292-895X
dc.identifier.issn1292-8941
dc.identifier.urihttps://depositonce.tu-berlin.de/handle/11303/6685
dc.identifier.urihttp://dx.doi.org/10.14279/depositonce-6126
dc.language.isoen
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subject.ddc530 Physik
dc.titleActive Brownian motion of emulsion droplets: coarsening dynamics at the interface and rotational diffusionen
dc.typeArticle
dc.type.versionpublishedVersion
dcterms.bibliographicCitation.articlenumber80
dcterms.bibliographicCitation.doi10.1140/epje/i2016-16080-y
dcterms.bibliographicCitation.issue8
dcterms.bibliographicCitation.journaltitleThe European physical journal E
dcterms.bibliographicCitation.originalpublishernameSpringer
dcterms.bibliographicCitation.originalpublisherplaceBerlin, Heidelberg
dcterms.bibliographicCitation.volume39
tub.accessrights.dnbfree
tub.affiliationFak. 2 Mathematik und Naturwissenschaften::Inst. Theoretische Physikde
tub.affiliation.facultyFak. 2 Mathematik und Naturwissenschaftende
tub.affiliation.instituteInst. Theoretische Physikde
tub.publisher.universityorinstitutionTechnische Universität Berlin
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