School of Mechanical Engineering: Dr. Ilya Barmak

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SCHOOL OF MECHANICAL ENGINEERING SEMINAR
Sunday, March 1, 2020 at 14:00
Wolfson Building of Mechanical Engineering, Room 206

COHERENT PARTICLE STRUCTURES IN THERMOCAPILLARY LIQUID BRIDGES

Dr. Ilya Barmak
Institute of Fluid Mechanics and Heat Transfer, TU Wien, Austria

When dispersed in a thermocapillary liquid bridge, small rigid particles are found to cluster into curious shapes, called particle accumulation structures (PAS). In this work particle accumulation is investigated numerically in high-Prandtl-number (Pr=68) liquid bridges under zero-gravity conditions. The accumulation process is studied in the framework of a one-way coupling approach. In this approximation the accumulation of multiple particles is modeled by the attraction of a single non-interacting particle to an attractor in or near Kolmogorov-Arnold-Moser (KAM) tori of the unperturbed fluid flow (without particles). The attractor is created by dissipative forces acting on the particle near the boundary due to the finite particle size and by inertia forces acting in the bulk in case of a particle-fluid density mismatch. In all cases the finite-size boundary effect is crucial for the existence of particle accumulation structures (PAS). Therefore, PAS in this system is a finite-size coherent structure (FSCS) the shape and existence range of which depends on the particle size and density. Calculations have been performed for various flow parameters and particle sizes and densities in order to provide numerical data for an optimum utilization of Japan European Research Experiment on Marangoni Instability (JEREMI) which is planned to be carried out on the International Space Station (ISS).