Oral: Effects of hydrodynamic interaction shaping nonequilibrium features of mesoscopic processes

Hydrodynamic interactions are known to bring forth interesting dynamical features in systems with colloidal particles trapped in close vicinity of each other. However, their role in affecting the overall irreversibility of such systems if they are taken out of equilibrium with time-dependent driving, or in the presence of different temperatures remains fairly unknown. In this work, we have addressed this issue - where we experimentally and theoretically show that the nonequilibrium characteristics of such systems can actually be tuned using hydrodynamic interactions. Our approach is based on the estimation of the total entropy production rate, which is a robust and scalable quantity computable from experimental data for systems with multiple degrees of freedom. We also clarify the characteristic differences between nonequilibrium configurations with hydrodynamic interactions and similar systems with elastic interactions in terms of the underlying forms of potential energy and local entropy production rate. These results illustrate the utility of hydrodynamic interactions to optimize not only dynamic properties but also irreversibility and energy dissipation, thereby opening new avenues for tailored control and design of driven mesoscale systems with targeted nonequilibrium characteristics.