Séminaire exceptionnel: Carlo Massimo Casciola (Sapienza University of Rome)

Nucleation of a second phase in a mother fluid is a ubiquitous phenomenon whose prediction proved a formidable task, particularly in the case of water. Phase transformations are part of our everyday experience, when boiling water to prepare tea or coffee, or for windows to fog up on cold and humid days. They are very complex processes originating at the molecular scale, where the continuous thermal agitation produces density fluctuations [1]. The computations are based on a Ginzburg-Landau model which, as only inputs, requires a reliable equation of state for the bulk free energy and the interfacial tension of the water-vapor system. Rare event techniques borrowed from statistical mechanics allow the determination of the free-energy barrier and the nucleation rate. By consistently including thermal fluctuations [2] in the spirit of Fluctuating Hydrodynamics, the approach is extended to dynamic conditions in the presence of solid walls of different wettability [3] to allow coupling with fluid motion [4]. The talk will discuss a wide range of phenomenologies, such as homogeneous and heterogeneous cavitation, nucleate boiling [5], confined nucleation, dropwise condensation, coupling with fluid flow, and a few exemplary applications highlighting collectiveeffects that may arise from the interaction of the nucleated phase with the mother fluid.

References:
[1] F. Magaletti, M. Gallo, C.M. Casciola, Water cavitation from ambient to high temperatures, Scie. Rep. 2021, 11 1.
[2] M. Gallo, F. Magaletti, C.M. Casciola, Thermally activated vapor bubble nucleation: the Landau-Lifshitz/Van der Waals approach, Phys. Rev. Fluids. 2018, 3, 053604.
[3] M. Gallo, F. Magaletti, C.M. Casciola, Heterogeneous bubble nucleation dynamics, J. Fluid Mech. 2021, 906 10.
[4] M. Gallo, F. Magaletti, D. Cocco, C.M. Casciola, Nucleation and growth dynamics of vapor bubbles, J. of Fluid Mech. 2020, 883.
[5] M. Gallo, F. Magaletti, A. Georgoulas, M. Marengo, J. De Coninck, C.M. Casciola, A nanoscale view of the origin of boiling and its dynamics. Nat. Comm. 2023, 14.1: 6428.

Contact: Xavier Noblin