SKM 2023 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 12: Modeling and Simulation of Soft Matter II
CPP 12.7: Vortrag
Montag, 27. März 2023, 17:00–17:15, MER 02
Wavenumber dependent viscosity of a system of particles coupled dissipatively to a Lattice Boltzmann fluid — •Joydip Chaudhuri1 and Burkhard Dünweg1,2 — 1Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany — 2Department of Chemical and Biological Engineering, Monash Univer- sity, Clayton, Victoria 3800, Australia
We consider a particle based Molecular Dynamics (MD) system coupled dissipatively to a stochastic Lattice Boltzmann (LB) fluid. The employed force coupling method is dissipative which means that the velocity of an MD particle is damped with respect to the velocity of the LB fluid interpolated to the position of the particle. The present study explores the viscosity response of such a coupled LBMD system due to a sinusoidally varying external force. The analytic theory for that system is based upon a two-fluid model, whose predictions are well corroborated by numerical tests. Except for the respective viscosities of the two uncoupled fluids, the total viscosity of the coupled system depends on a hydrodynamic screening length associated with the Stokes coupling parameter, the mass density ratio, and the wavenumber of the applied external force. In the asymptotic long-wavelength limit, the total viscosity is just the sum of the two input viscosities. This behavior deviates significantly from the well known Einstein prediction for dilute colloidal dispersions, and this is due to the different type of particle-fluid coupling.