Contact line motion in axial thermocapillary outward flow

Torres, A.; Intyre, Jonatan R. Mac; Gomba, J. M.; Perazzo, Carlos Alberto; Correa, Pablo Germán; López-Villa, A.; Medina, A.

doi:10.1017/jfm.2020.172

Cited by 11 publications

(13 citation statements)

References 34 publications

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“…Thus, the interface temperature of the droplet can be regarded as the same as that at the underlying substrate. 35,36 When the laser beam is sweeping, a comet-shaped thermal pattern is formed. The maximum surface temperature (approximately 28.7 °C) was slightly lower than that in the case of the fixed laser beam (approximately 28.9 °C).…”

Section: Resultsmentioning

confidence: 99%

Light-manipulated binary droplet transport on a high-energy surface

Li,

Zhu

et al. 2023

Lab Chip

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Section: Resultsmentioning

confidence: 99%

Light-manipulated binary droplet transport on a high-energy surface

Li,

Zhu

et al. 2023

Lab Chip

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“…Asumiendo que la conductividad térmica del líquido es alta, es decir que los números de Péclet y Biot son pequeños, el gradiente térmico en la superficie del líquido será idéntico al del substrato (en la Ref. [1] se reportan valores típicos de los números de Péclet y de Biot de 0.05 y 0.04, respectivamente). Esto ocasiona que en la superficie del líquido se genere un gradiente de tensión superficial responsable del flujo hacia afuera (de la región más caliente hacia la región más fría) [11].…”

Section: El Problema Y Sus Ecuacionesunclassified

“…La motivación de este trabajo se basa en los experimentos realizados por Domínguez et al [1], en los que se deposita una gota sobre el centro de una superficie circular sólida, cuya temperatura decrece con el radio. Este gradiente de temperatura en el sustrato induce un esfuerzo de Marangoni en la interfaz líquido-aire, que desplaza el líquido radialmente hacia afuera.…”

Section: Introductionunclassified

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3d Numerical Simulations of the Flow of a Drop Under the Effectsof a Radial Temperature Gradient

Escobar Quiroz,

Mansilla,

Gomba

et al. 2024

AnAFA

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It has been shown experimentally that when a drop is deposited at the center of a substrate with an axial temperature gradient (hotter in the center), thermocapillarity effects makes an outward flow to appear so that the drop evolves towards a ring whose radius increases with time. Upon reaching a critical radius, the contact line becomes unstable, showing gentle undulations whose amplitudes grow with time. Using the lubrication approximation and adopting appropriate dimensionless variables, a parameter-free differential equation is obtained that governs this type of thermocapillary flow. Numerical solutions of this equation are presented to study the unstable stage. Experimental results are compared with those obtained from the numerical solutions.

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“…This phenomenon is known as the thermocapillary or thermal Marangoni actuation of droplets (Young, Goldstein & Block 1959;Subramanian & Balasubramaniam 2001). The complex interfacial dynamics of droplet spreading over non-isothermal substrates have prompted a number of experimental and theoretical investigations over the last few decades (Ehrhard & Davis 1991;Brzoska, Brochard-Wyart & Rondelez 1993;Pratap, Moumen & Subramanian 2008;Gomba & Homsy 2010;Sui 2014;Chaudhury & Chakraborty 2015;Sui & Spelt 2015;Mac Intyre et al 2018;Dominguez Torres et al 2020;Xu et al 2021). The theoretical study of Ehrhard & Davis (1991) employed the lubrication approximation of the Navier-Stokes equations by exploiting the disparity between the length scale of the droplet along the spreading direction and the drop height.…”

Section: Introductionmentioning

confidence: 99%

Rheology dictated spreading regimes of a non-isothermal sessile drop

Mantripragada

Poddar

2022

J. Fluid Mech.

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In the present work, within the framework of thin film theory, we delineate the interaction between the interfacial dynamics of thermal Marangoni flow and non-Newtonian rheology by considering a spreading droplet over a non-isothermal substrate. The numerical simulations, performed at different equilibrium contact angles $(\theta _e)$ , dimensionless thermocapillary strengths $(\beta )$ and shear-dependent viscosities $(n)$ , reveal that the fluid rheology nonlinearly influences the mechanisms of disjoining pressure and Marangoni stress. Accordingly, three distinct spreading regimes for non-Newtonian drops arise. Results indicate that the Marangoni film regime, having an approximate linear drop shape, sustains at lower $\theta _e$ , higher $\beta$ and $n$ ranges. Also, shear-thickening drops display an early onset of thermocapillary time scale and a steeper advancing front, while their shear-thinning counterparts retain a significant curvature for a much longer time. Contrastingly, the droplet regime is identified by fixed shape and uniform speed $(U)$ at higher $\theta _e$ and lower $(\beta$ , $n)$ combinations. Here, an intricate interplay between $\beta$ and $n$ realizes a sharp increase in $U$ for shear thinning compared with its invariance for shear-thickening droplets. The transition regime appears as an intermediate regime between the other two and involves multiple ruptured droplets. In all the regimes, we observe slower (faster) spreading of shear-thinning (thickening) droplets than the Newtonian droplets. In addition, the variations in $n$ cause intense characteristic modulations to spreading attributes like droplet morphology and transient spreading behaviour, and also act as a switching mechanism between different spreading regimes. These unique results may be utilized for superior control of non-isothermal biofluid droplets in microfluidics.

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Contact line motion in axial thermocapillary outward flow

Cited by 11 publications

References 34 publications

Light-manipulated binary droplet transport on a high-energy surface

Light-manipulated binary droplet transport on a high-energy surface

3d Numerical Simulations of the Flow of a Drop Under the Effectsof a Radial Temperature Gradient

Rheology dictated spreading regimes of a non-isothermal sessile drop

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