2024/02/27 by Christian Diddens, Diddens, Christian, Pim J. Dekker +3 · 2 citations
Engineering · #Electrohydrodynamics and Fluid Dynamics #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Heat Transfer #Nanomaterials and Printing Technologies
paper · pdf · doi:10.48550/arxiv.2402.17452
openalex publication_date 2024/02/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
The evaporation of water/1,2-hexanediol binary drops shows remarkable segregation dynamics, with hexanediol-rich spots forming at the rim, thus breaking axisymmetry. While the segregation of hexanediol near the rim can be attributed to the preferential evaporation of water, the symmetry-breaking and spot formation could not yet be successfully explained. With three-dimensional simulations and azimuthal stability analysis of a minimal model, we investigate the flow and composition in the drop. We show that a slightly non-monotonic surface tension causes the emergence of a counter-rotating Marangoni vortex in the hexanediol-rich rim region, which subsequently becomes azimuthally unstable and forms the observed spots. Accurate measurements with several different methods reveal that the surface tension is indeed non-monotonic. This work provides valuable insight for applications like inkjet printing or spray cooling.