Master's thesis defense: Serhii Yaskovets

Student presentation (Master's thesis defense)
Speaker: Serhii Yaskovets
Contact: Prof. Dr. Axel Voigt, Dr. Simon Praetorius

Titel: Collective Behaviour of Active Brownian Particles by Active VPFC Modeling
Abstract: Active matter systems, natural or artificial, convert energy obtained from environment to drive themselves out of their euqilibrium. They exhibit collective behaviour not shown by matter at thermal equilibrium. In this work we implement a minimal model of active brownian particles (ABPs) via use of active vacancy phase field crystal (active VPFC) model. The microscopic field theoretical approach of this model has
an advantage of representing multiple particles through one phase field while not constraining particle shape or symmetry. At the same time the approach requires fewer resources than multiphase-field models, hence is an intermediate solution between those and agent-based active particle models. In the previous works the microscopic field theoretical approach was applied to model ABPs together with additional alignment fields like a polar particle orientation field P or a nematic Q-tensor field Q to guide the self-propulsion of active particles. In this work a simplified model is formulated, where direction of motion is represented by realisations of an independent stochastic processes for every object. The model is used to simulate motility and interactions of ABPs in confined and unconfined domains. Adaptive finite element methods toolbox AMDiS and an open source framework for grid-based numerical solution of PDEs DUNE are used to simulate the model. The phenomena observed are assessed both qualitatively and quantitatively, and later compared with the previous results.