Temperature imaging of buoyancy-driven flows using lifetime-based laser-induced phosphorescence of particles

Recent advancements in fluid experimentation have made it possible to visualize local temperature in flows by observing the response of photoluminescent dye or particles to light excitation. This has sparked increased interest in exploring laboratory-scale density currents induced by temperature differences. However, unlike the commonly investigated saltwater-freshwater or turbidity currents, heat transfer through boundaries can occur, potentially influencing the dynamics of the buoyancy-driven current.

In this study, we utilize the luminescence lifetime dependence on ambient fluid temperature of phosphor micrometric particles (YAG:Cr) and dye (Zr(PDP)₂), to spatially and temporally resolve gravity currents such as lock-exchange flows. Notably, we introduce a novel approach by demonstrating the use of CMOS sensors coupled with an accumulation technique to extract temperature information from high resolution images. This method holds promise as it significantly enhances the accessibility of temperature imaging techniques for experimenters. This innovative approach is adaptable to various experimental setups studying thermal convection in fluid bodies.