International Symposium: NON-EQUILIBRIUM TRANSITIONS IN CONTINUOUS MEDIA

Description

Plenary Lecture Title: Stationary Solid-particle Attractors in non-equilibrium conditions under thermovibrational stimuli

It is shown that, despite the intrinsic non-equilibrium features of the involved thermofluid-dynamic phenomena, the application of time-periodic mechanical stimuli to a fluid containing dispersed inertial solid particles, in combination with a fixed imposed temperature difference, can support the emergence of stationary particle structures if the disturbing influence of steady gravity is removed. This line of inquiry stems from a theory formulated more than a decade ago about the existence of specific particle “attractee” (attractors) in the fluid domain driven by the unique interplay established among purely (particle-related) inertial effects, the influence of the container boundary and the thermovibrational flow itself. Such theoretical predictions have recently been confirmed through dedicated experiments conducted on board the ISS using the Selectable Optical Diagnostic Instrument (SODI) in conjunction with the Microgravity Science Glovebox (MSG). Supporting numerical simulations conducted in the framework of a one-way coupled Eulerian-Lagrangian (liquid-solid) approach have confirmed that the non-equilibrium nature of the host flow is instrumental in producing local disturbances (in the particle motion) due to a mismatch between their trajectories and the streamlines of the carrier fluid. These perturbations amplify with time thereby moving the whole particle system into an unstable or metastable state where all the dispersed matter collapses on well-defined surfaces or accumulation loci. Additional numerical simulations, taking into account the back influence of particles on fluid flow (two-way coupling), indicate that reverse momentum transfer is not a necessary ingredient; however, it can cause the complete suppression of these phenomena as soon as a critical particle concentration is exceeded. An increased level of coupling, where particle-to-particle effects are even accounted for (through a multi-particle gas-like kinetic model or more sophisticated strategies), finally demonstrates that, although not strictly required for the existence of particle attractors, inter-particle stresses can trigger symmetry-breaking mechanisms and cause compaction or dilation of the effectively formed particle structures.

Period	2024
Event type	Conference
Location	Perm, Russian FederationShow on map
Degree of Recognition	International