Sedimentation of binary mixtures: Phase stacking and Nonequilibrium dynamics

• Applicants: Professor Dr. Daniel de las Heras; Professor Dr. Matthias Schmidt
• Subject Area: Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 436306241

Gravitational and thermal energies are of comparable magnitude in colloidal systems. As a result colloidal sedimentation is a complex phenomenon in colloidal mixtures. We will make use of computer simulations and theory to develop general frameworks for the theoretical description of the sedimentation-diffusion equilibrium (part I) and the dynamics of sedimentation (part II) in colloidal mixtures. In part I, we will use Monte Carlo simulations, classical density functional theory, and the recently developed theory of stacking diagrams to (i) study the sedimentation of mixtures of colloidal rods, (ii) incorporate surface effects into the stacking diagrams of colloidal mixtures, and (iii) extend the stacking diagrams to the case of ternary and multicomponent systems. In part II we will analyse the (i) homogeneous and inhomogeneous steady states of colloidal mixtures in a gravitational field, (ii) the dynamics of phase separation under gravity, and (iii) the full time-dependent dynamics of sedimentation from a homogeneous state to the final sedimentation-diffusion equilibrium. We will use Brownian dynamics simulations to obtain results for the dynamical evolution of the system and, in particular, for the internal force field. The results will then be used to formulate power functional approximations for the dynamics of sedimentation in colloidal systems at all length and time scales.

• DFG Programme: Research Grants