Irreversibility of mesoscopic processes with hydrodynamic interactions

Microscopic colloidal particles are often used as probes to study the non-equilibrium activity of living matter or other complex systems. In many of these contexts hydrodynamic interactions between the probe particle and the system of interest play an important role. However little is known about what effect such interactions could have on the overall non-equilibrium characteristics of the system of interest. In this paper, we study two simple models experimentally and theoretically, which demonstrate that hydrodynamic interactions could either diminish or enhance the total entropy production of the combined system. Importantly, we show that our method of calculating entropy production helps identify heat flows consistently, even in the presence of hydrodynamic interactions. The results indicate that interactions can be finely tuned 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.