Improving energy efficiency in industrial cooling systems hinges on the precise control and enhancement of heat transfer, a challenge that demands innovative solutions. While traditional approaches focus on heat exchanger geometry or fluid circulation speed, modulating the fluid’s intrinsic properties presents a promising yet relatively less explored path. In this study, we use laser-induced fluorescence through a Taylor-Couette cell to experimentally identify the interplay between fluid composition and rheology, hydrodynamic regimes, and mixing enhancement ultimately leading to transfer intensification. By measuring time evolving concentration fields upon injection of dye droplets, we quantify mixing dynamics across a spectrum of complex fluids, revealing how complex physical properties induced by the presence of microparticles, nanoparticles, and polymers reshape flow patterns and/or impact mixing times. Our findings underscore the increase in advection in triggering elasto-inertial turbulence by polymer addition, a regime that dramatically accelerates mixing. While dilute particle suspensions universally enhance convective performance (to the notable exception of that nanoparticles added into wavy flows), excessive particle loading paradoxically degrades elasto-inertial mixing efficiency, thus developing non-chaotic regimes (elasto-inertial dissipation, EID). Without any visible coherent scalar structure associated to it, this recently discovered regime still outperforms laminar flow in terms of mixing. This study thus highlights the potential of complex suspensions as efficient convection enhancers and of Taylor-Couette flows as a quick way of screening the convective potential of heat transfer fluids in centrifugal and/or curved flow contexts.
Carré et al. (2026) studied this question.