05/2024 Nonlinear Response Theory of Molecular Machines Michalis Chatzittofi et al.
Chemical affinities are responsible for driving active matter systems out of equilibrium. At the nano-scale, molecular machines interact with the surrounding environment and are subjected to external forces. The mechano-chemical coupling which arises naturally in these systems reveals a complex interplay between chemical and mechanical degrees of freedom with strong impact on their active mechanis …
05/2024 Mobility-induced kinetic effects in multicomponent mixtures Filipe C. Thewes et al.
We give an overview exploring the role of kinetics in multicomponent mixtures. Compared to the most commonly studied binary (single species plus solvent) case, multicomponent fluids show a rich interplay between kinetics and thermodynamics due to the possibility of fractionation, interdiffusion of mixture components and collective motion. This leads to a competition between multiple timescales tha …
05/2024 Chirotactic response of microswimmers in fluids with odd viscosity Yuto Hosaka et al.
Odd viscosity is a property of chiral active fluids with broken time-reversal and parity symmetries. We show that the flow of such a fluid around a rotating axisymmetric body is exactly solvable and use this solution to determine the orientational dynamics of surface-driven microswimmers. Swimmers with a force-dipole moment exhibit precession around the axis of the odd viscosity. In addition, push …
05/2024 Scaling of phase count in multicomponent liquids Yicheng Qiang et al.
Mixtures with many components can segregate into coexisting phases, e.g., in biological cells and synthetic materials such as metallic glass. The interactions between components dictate what phases form in equilibrium, but quantifying this relationship has proven difficult. We derive scaling relations for the number of coexisting phases in multicomponent liquids with random interactions and compos …
04/2024 Patterns of active dipolar particles in external magnetic fields Vitali Telezki et al.
Active particles with a (magnetic) dipole moment are of interest for steering self-propelled motion, but also result in novel collective effects due to their dipole-dipole interaction. Here systems of active dipolar particles are studied with Brownian dynamics simulations to systematically characterize the different patterns they form, specifically in the presence of an external (magnetic) field. …
04/2024 Entangled nematic disclinations using multi-particle collision dynamics Louise C. Head et al.
Colloids dispersed in nematic liquid crystals form topological composites in which colloid-associated defects mediate interactions while adhering to fundamental topological constraints. Better realising the promise of such materials requires numerical methods that model nematic inclusions in dynamic and complex scenarios. We employ a mesoscale approach for simulating colloids as mobile surfaces em …
04/2024 Emergent polar order in non-polar mixtures with non-reciprocal interactions Giulia Pisegna et al.
Phenomenological rules that govern the collective behaviour of complex physical systems are powerful tools because they can make concrete predictions about their universality class based on generic considerations, such as symmetries, conservation laws, and dimensionality. While in most cases such considerations are manifestly ingrained in the constituents, novel phenomenology can emerge when compo …
03/2024 Molecular Dynamics Simulations of Microscopic Structural Transition and Macroscopic Mechanical Properties of Magnetic Gels Xuefeng Wei et al.
Magnetic gels with embedded micro/nano-sized magnetic particles in crosslinked polymer networks can be actuated by external magnetic fields, with changes in their internal microscopic structures and macroscopic mechanical properties. We investigate the responses of such magnetic gels to an external magnetic field, by means of coarse-grained molecular dynamics simulations. We find that the dynamics …
03/2024 Tangential diffusion and motility-induced mixing transition in exponentially growing multicellular spheroids Torben Sunkel et al.
Growth is a known driver of cellular dynamics in a range of dense aggregates from bacterial colonies to developing tissues to tumors. Hence, universal physical principles underlying these dynamics are of great interdisciplinary interest. Here, we study the emergent dynamics arising from the interplay of growth, steric repulsion and motility in a minimal agent-based model of exponentially growing t …
03/2024 Multiphase Field Model of Cells on a Substrate Michael Chiang et al.
Multiphase field models have emerged as an important computational tool for understanding biological tissue while resolving single-cell properties. While they have successfully reproduced many experimentally observed behaviors of living tissue, the theoretical underpinnings have not been fully explored. We show that a two-dimensional version of the model, which is commonly employed to study tissue …