Topic
Marangoni effect
About: Marangoni effect is a research topic. Over the lifetime, 5336 publications have been published within this topic receiving 98562 citations. The topic is also known as: Gibbs–Marangoni effect.
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TL;DR: Experimental results and numerical simulations show that this microsepration occurs as a result of a series of processes driven by mass and heat transfer, and can be used for on-chip synthesis of advanced particles and innovative microbioassays.
Abstract: We describe phenomena of colloidal particle transport and separation inside single microdroplets of water floating on the surface of dense fluorinated oil. The experiments were performed on microfluidic chips, where single droplets were manipulated with alternating electric fields applied to arrays of electrodes below the oil. The particles suspended in the droplets were collected in their top region during the evaporation process. Experimental results and numerical simulations show that this microsepration occurs as a result of a series of processes driven by mass and heat transfer. An interfacial tension gradient develops on the surface of the droplet as a result of the nonuniform temperature distribution during the evaporation. This gradient generates an internal convective Marangoni flow. The colloidal particles transported by the flow are collected in the top of the droplets by the hydrodynamic flux, compensating for evaporation through the exposed top surface. The internal flow pattern and temperature distribution within evaporating droplets were simulated using finite element calculations. The results of the simulation were consistent with experiments using tracer particles. Such microseparation processes can be used for on-chip synthesis of advanced particles and innovative microbioassays.
83 citations
TL;DR: In this paper, a simulation of laser powder bed fusion of stainless steel 316-L single tracks was simulated by using computational fluid dynamics, which revealed the various effects of surface tension, Marangoni shear force, viscous force and recoil pressure on the humping phenomenon.
83 citations
TL;DR: Direct imaging reveals that silica microspheres suspended within an organic solvent exhibit recirculating flows induced by temperature and surface tension gradients that arise during drying, leading to particle deposition in unmasked regions of high evaporative flux.
Abstract: We investigate the effects of Marangoni stresses on the evaporative lithographic patterning of colloidal films (Harris, D. J.; Hu, H.; Conrad, J. C.; Lewis, J. A. Phys. Rev. Lett. 2007, 98 (14), 148301). Films are dried beneath a mask that induces periodically varying regions of free and hindered evaporation. Direct imaging reveals that silica microspheres suspended within an organic solvent exhibit recirculating flows induced by temperature and surface tension gradients that arise during drying. The films display remarkable pattern formation with a majority of the particles deposited in the masked regions. Above a critical colloid volume fraction, recirculating flows are suppressed, leading to particle deposition in unmasked regions of high evaporative flux.
83 citations
TL;DR: In this article, computational thermal-fluid dynamics simulations with multi-physical modeling and proof-of-concept experiments were used to analyze the molten pool behavior and resultant thermal conditions related to solidification.
Abstract: Selective electron beam melting (SEBM) is a type of additive manufacturing (AM) that involves multiple physical processes. Because of its unique process conditions compared to other AM processes, a detailed investigation into the molten pool behavior and dominant physics of SEBM is required. Fluid convection involves mass and heat transfer; therefore, fluid flow can have a profound effect on solidification conditions. In this study, computational thermal-fluid dynamics simulations with multi-physical modeling and proof-of-concept experiments were used to analyze the molten pool behavior and resultant thermal conditions related to solidification. The Marangoni effect of molten metal primarily determines fluid behavior and is a critical factor affecting the molten pool instability in SEBM of the Co–Cr–Mo alloy. The solidification parameters calculated from simulated data, especially the solidification rate, are sensitive to the local fluid flow at the solidification front. Combined with experimental analysis, the results presented herein indicate that active fluid convection at the solidification front increase the probability of new grain formation, which suppresses the epitaxial growth of columnar grains.
83 citations