Thursday, July 13 2023
11:30 - 13:00

Alladi Ramakrishnan Hall

Mpemba effect in granular and Langevin systems (thesis talk)

Apurba Biswas

The Institute of Mathematical Sciences

The Mpemba effect is a counter-intuitive relaxation phenomenon in which a hotter system equilibrates faster than a colder system when both systems are quenched to the same low temperature. The effect was first discovered in the case of water, where it is described in terms of freezing times. However, the effect is more general and can be studied in the context of quenched relaxation dynamics of generic physical systems. In this talk, we describe the Mpemba effect in driven granular gases, an example of an interacting many-particle nonequilibrium system, as well as a single-particle setup of a colloidal Langevin system. Both these examples allow for a strong interplay between theory and experiment. An exact analysis determining the criteria for the Mpemba effect in both systems will be presented. For granular systems, we trace the cause of the Mpemba effect to anisotropy in the kinetic energies while for Langevin systems, it is the presence of metastable states in the energy landscape. Our recent study demonstrates that the Mpemba effect can exist even in the absence of a metastable state, providing new insight into the relaxation phenomenon.

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