Dokument: Transport Coefficients in Dense Active Brownian Particle Systems
| Titel: | Transport Coefficients in Dense Active Brownian Particle Systems | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=55375 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20210210-104231-0 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Reichert, Julian [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Voigtmann Thomas [Betreuer/Doktorvater] Prof. Dr. Löwen, Hartmut [Gutachter] | |||||||
| Stichwörter: | non-equilibrium statistical physics, dense active matter, active brownian particles, microswimmers, mode-coupling theory, glass transition | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 530 Physik | |||||||
| Beschreibung: | The investigation of transport phenomena in crowded active matter is of substantial interest to obtain a fundamental understanding of many biophysical processes, such as the dynamics of cells and the associated mechanisms of morphogenesis. Despite their great relevance, the underlying physical principles are insufficiently understood in lack of appropriate theories for dense systems far from equilibrium. One out of the few theoretical approaches that are capable to address the regime of high densities under non-equilibrium conditions is given by a recent formulation of the mode-coupling theory of the glass transition to describe the collective dynamics of active Brownian particles. By suitably extending this mode-coupling approach, this work aims to investigate non-equilibrium transport coefficients in dense suspensions of active particles in two dimensions.
Starting from a microscopic description, the central quantity of this work is given by the transient correlation function of two angle-resolved microscopic densities in mixtures of active and passive particles, the approximation of which within the framework of the mode-coupling theory constitutes the first goal. Based on the resulting equations, further mode-coupling approaches are derived to predict the transient dynamics and the mean-squared displacement of active or passive tagged particles in both active and passive dense host environments. Moreover, the mode-coupling approximated dynamical correlation functions are exploited to approximate Green-Kubo-type expressions for further transport coefficients such as the viscosity and the effective swimming velocity that can be derived within the framework of the integration-through-transients formalism. A central constituent of the present work comprises a test of the mode-coupling theory for active Brownian particles against results from a simulation of event-driven active Brownian hard-disks. Both methods deliver largely qualitative, and in some cases near quantitatively consistent results. This provides an important contribution to assess the applicability of the theory and the general quality of its used approximations. Moreover, the use of two independent methods leads to a deeper understanding of the universal properties of active transport at high densities that have been barely addressed so far. A governing principle arises in the presence of competing length scales, represented by the cageing length of volume exclusion and the persistence length of active locomotion. This principle has played a subordinate role for most previous approaches for model systems of active particles, which mainly referred to diluted systems or systems of moderate densities, but is of decisive importance at high densities. The methods of this work are further employed to assess current experimental results from a setup with diffusiophoretic active Janus particle in a binary colloidal mixture close to the glass transition point. In a final part of this work, mixing effects in monodisperse systems of active and passive particles are discussed with respect to the influences of the composition and the strength of the activity of the components on the dynamics and the glass transition. The results reveal the possibility to influence the viscosity of samples by targeted doping with active particles. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät | |||||||
| Dokument erstellt am: | 10.02.2021 | |||||||
| Dateien geändert am: | 10.02.2021 | |||||||
| Promotionsantrag am: | 10.11.2020 | |||||||
| Datum der Promotion: | 17.12.2020 |
