Martedì 19 novembre alle 14.30 ospite dei Seminari Generali dell'IAC sarà Francesca Pelusi, ricercatrice del CNR IAC, sede di Napoli.
Il seminario, dal titolo Thermal Convection in Emulsions: Heat Transfer Properties and Role of Droplets, si svolge come sempre in modalità mista, in presenza, nella sala 1 del CNR-IAC sede di Napoli, Via P. Castellino 11 e streaming (vedi link in calce).
Di seguito l'abstract.
This study explores the dynamics of emulsions—liquid droplets dispersed within another liquid—under buoyancy-driven thermal convection using lattice Boltzmann numerical simulations. We focus on the heat transfer properties of emulsions with varying droplet concentrations, examining cases from dilute to highly concentrated yield-stress emulsions exhibiting a complex non-Newtonian rheology. We investigate how the combination of complex rheology and the presence of finite-sized droplets influences the statistically steady convective state of emulsions under thermal convection. Specifically, at low buoyancy forces, just above the conduction-to-convection transition, we observe that heat transfer fluctuations increase with droplet concentration, due to the presence of finite-sized droplets. However, if the emulsion exhibits a yield-stress non-Newtonian behavior, the transition to convection requires an initial intermittent transient dynamics, during which rapid bursts of heat transfer are spaced out by long-lasting conductive periods, ultimately leading to phase inversion. To complete the above scenario, we then increase the buoyancy force and observe that it can trigger significant structural changes: droplets may undergo breakup, coalescence, and even phase inversion, resulting in a drastic variation in the emulsion rheology. Our findings link macroscopic heat transfer properties to droplet-scale dynamics, providing new insights into complex fluid behavior with broad applications in materials science, pharmaceuticals, and beyond.
