Buoyancy-Marangoni Fingering of a Miscible Spreading Drop

Hooshanginejad, Alireza; Jung, Sunghwan

doi:10.3390/sym14020425

Cited by 3 publications

(1 citation statement)

References 34 publications

(41 reference statements)

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“…Furthermore, they validated their model using previous experimental and analytical studies. Hooshanginejad et al [ 14 ] conducted experiments to explore the dynamics (instability) of water droplets on glycerol–water solutions. They observed the formation of fingering patterns that were developed from the interplay between outward buoyancy and inward Marangoni flow.…”

Section: Introductionmentioning

confidence: 99%

The Impact of Marangoni and Buoyancy Convections on Flow and Segregation Patterns during the Solidification of Fe-0.82wt%C Steel

Sari,

Wu,

Ahmadein

et al. 2024

Materials

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Due to the high computational costs of the Eulerian multiphase model, which solves the conservation equations for each considered phase, a two-phase mixture model is proposed to reduce these costs in the current study. Only one single equation for each the momentum and enthalpy equations has to be solved for the mixture phase. The Navier–Stokes and energy equations were solved using the 3D finite volume method. The model was used to simulate the liquid–solid phase transformation of a Fe-0.82wt%C steel alloy under the effect of both thermocapillary and buoyancy convections. The alloy was cooled in a rectangular ingot (100 × 100 × 10 mm3) from the bottom cold surface to the top hot free surface by applying a heat transfer coefficient of h = 600 W/m2/K, which allows for heat exchange with the outer medium. The purpose of this work is to study the effect of the surface tension on the flow and segregation patterns. The results before solidification show that Marangoni flow was formed at the free surface of the molten alloy, extending into the liquid depth and creating polygonized hexagonal patterns. The size and the number of these hexagons were found to be dependent on the Marangoni number, where the number of convective cells increases with the increase in the Marangoni number. During solidification, the solid front grew in a concave morphology, as the centers of the cells were hotter; a macro-segregation pattern with hexagonal cells was formed, which was analogous to the hexagonal flow cells generated by the Marangoni effect. After full solidification, the segregation was found to be in perfect hexagonal shapes with a strong compositional variation at the free surface. This study illuminates the crucial role of surface-tension-driven Marangoni flow in producing hexagonal patterns before and during the solidification process and provides valuable insights into the complex interplay between the Marangoni flow, buoyancy convection, and solidification phenomena.

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Section: Introductionmentioning

confidence: 99%

The Impact of Marangoni and Buoyancy Convections on Flow and Segregation Patterns during the Solidification of Fe-0.82wt%C Steel

Sari,

Wu,

Ahmadein

et al. 2024

Materials

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Influence of thermocapillary flow induced by a heated substrate on atomization driven by surface acoustic waves

et al. 2023

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Thermocapillary flow on the mechanism of interfacial destabilization prior to atomization of a sessile Newtonian droplet subjected to surface acoustic waves (SAWs) is analyzed. We assumed that an interfacial temperature distribution is induced on the free surface of the millimeter-sized water droplet since the droplet is on a heated substrate. Given the dependence of surface tension on interfacial temperature, shear stresses combined with SAWs lead to the development of thermocapillary flow. The evolution equation for a small-scale droplet under the combined influence of SAW atomization and thermocapillary flow is derived via an asymptotic approach to the hydrodynamic equations, arising the acoustic capillary and Marangoni numbers. In this limit, our simplified droplet model can predict capillary instability leading to atomization once a critical amplitude is reached for the induced capillary waves at the liquid droplet. In doing so, our model also represents the influence of the thermocapillary effect on the interfacial deformation of the droplet and shows how the Marangoni flow promoted by a heated substrate counteracts the acoustic stress, leading to a virtually uniform droplet aspect ratio and thus larger aerosol diameters compared to the isothermal case. These results are supported by the development of a novel analytical expression that has allowed us to estimate the characteristic aerosol size under thermocapillary flow and SAW excitation, and to postulate thermocapillary flow as a new valuable means of explaining the regulation of the characteristic aerosol size at SAW atomization.

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