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BP: Fachverband Biologische Physik
BP 28: Microswimmers and Microfluidics (joint session DY/BP/CPP)
BP 28.7: Vortrag
Donnerstag, 20. März 2025, 17:00–17:15, H37
Motion of a single particle partially exposed in a simple shear flow — •Dominik Geyer1,2, Aouane Othmane1, and Jens Harting1,2 — 1Helmholtz-Institut Erlangen-Nürnberg for Renewable Energy (IET-2), FZ Jülich — 2Department of Physcis, FAU Erlangen-Nürnberg
Sand immersed in the water can be imagined as a wet granular matter. Besides sedimentation, friction, and surface roughness are two relevant physical phonemes within this system. Many body systems in a turbulent regime have been studied using discrete elements methods for a long time, but a single particle in the Stokes flow regime is particularly interesting for biological systems and microfluidic devices.
A layer of quadratic-arranged spheres models the rough surface. The question arises of how to describe the motion of a single traveling particle over this substrate.
We choose a combined numerical and analytical approach. The Stokes equation is solved analytically for the sphere near a rough wall. Lattice Boltzmann simulations with momentum-exchange particle coupling are performed for different wall roughness and friction coefficients.
Although, the Stokes equation assumes that the particle Reynolds number is zero. Surprisingly, the numerical results match our theoretical description until a particle Reynolds number of two. In this regime, friction between the moving particle and the substrate significantly influences the angular velocity but has a minor influence on the traveling velocity in the flow direction.
Keywords: Particle motion; Rough surface; Small Reynolds number; Wet granular matter; Lattice Boltzmann