Abnormal evaporative flux on binary mixture droplets

An evaporating binary mixture droplet has been substantially investigated for its industrial applications, such as spray cooling, inkjet printing, uniform coating, and evaporation-induced self-assembly (EISA), as well as the intriguing physical phenomena it presents. However, a complete understanding of the dynamic flow transition remains elusive due to changing initial concentration conditions caused by the relative evaporation rates and density stratification between two different liquid components. This gap in understanding is mainly due to the reliance on indirect investigation methods, such as Particle Image Velocimetry (PIV) to study local effects. To address this issue, we recently conducted a direct visualization of the evaporated vapor distribution in the gas phase. Using this approach, we successfully measured the evaporative flux of a single component of the droplet. In this talk, we will present the direct evaporative flux measurement results of the binary mixture droplet using laser interferometry. Our findings show that the location of the maximum evaporative flux shifts from the contact line to the top apex of the binary mixture droplet. These results are consistent with those obtained from PIV measurements.