Speaker
Description
Thermally induced Marangoni stresses play a crucial role in transport phenomena at fluid interfaces in confined microfluidic environments, yet their interplay with evaporation, geometry, and interfacial dynamics remains incompletely understood. In this work, we present an experimental investigation of the thermal Marangoni effect in microcapillaries of varying characteristic sizes fabricated via soft lithography in polydimethylsiloxane (PDMS) micromodels. Evaporation-driven flows are studied for both volatile and non-volatile liquid mixtures, allowing systematic control of concentration gradients and associated surface tension variations.
The influence of capillary size on the onset and intensity of Marangoni convection is quantified, revealing distinct flow regimes as confinement is varied. In addition, the role of ambient relative humidity at the evaporating front is examined, highlighting its impact on evaporation rates, temperature gradients, and resulting interfacial stresses. Particular attention is devoted to the dynamics of the liquid–gas interface, including interface deformation and unsteady motion, and their consequences for particle transport and accumulation.
Using particle tracking and optical visualization, we analyze the fate of suspended particles near the evaporating interface and identify conditions leading to enhanced trapping or removal. These results provide new insights into the coupled effects of thermal gradients, evaporation, and confinement on interfacial transport, with implications for microfluidic design, coating processes, and particle manipulation at small scales.
| Country | Germany |
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