Buoyancy and Marangoni Effects in an Evaporating Drop

Savino, Raffaele; Paterna, D.; Favaloro, N.

doi:10.2514/2.6716

Cited by 89 publications

(84 citation statements)

References 15 publications

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“…Before entering the E.C region, the streamlines ascend along the droplet surface towards the upper part of the droplet and then return to the bottom. Such a flow field agrees with those reported in the literature [33][34][35]. When keeping T S at 5°C, on the other hand, the direction of streamlines of Marangoni flow reverse and become clockwise; they move from the region next to the E.C.…”

Section: Simulation Of Hydrodynamic Flows In Drying Dropletssupporting

confidence: 81%

Reducing Spatial Heterogeneity of MALDI Samples with Marangoni Flows During Sample Preparation

Lai

Cai

Lee

et al. 2016

J. Am. Soc. Mass Spectrom.

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Abstract. This work demonstrates a method to prepare homogeneous distributions of analytes to improve data reproducibility in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). Natural-air drying processes normally result in unwanted heterogeneous spatial distributions of analytes in MALDI crystals and make quantitative analysis difficult. This study demonstrates that inducing Marangoni flows within drying droplets can significantly reduce the heterogeneity problem. The Marangoni flows are accelerated by changing substrate temperatures to create temperature gradients across droplets. Such hydrodynamic flows are analyzed semi-empirically. Using imaging mass spectrometry, changes of heterogeneity of molecules with the change of substrate temperature during drying processes are demonstrated. The observed heterogeneities of the biomolecules reduce as predicted Marangoni velocities increase. In comparison to conventional methods, drying droplets on a 5°C substrate while keeping the surroundings at ambient conditions typically reduces the heterogeneity of biomolecular ions by 65%-80%. The observation suggests that decreasing substrate temperature during droplet drying processes is a simple and effective means to reduce analyte heterogeneity for quantitative applications.

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Section: Simulation Of Hydrodynamic Flows In Drying Dropletssupporting

confidence: 81%

Reducing Spatial Heterogeneity of MALDI Samples with Marangoni Flows During Sample Preparation

Lai

Cai

Lee

et al. 2016

J. Am. Soc. Mass Spectrom.

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“…The appearance of Marangoni convection in water droplets has however been questioned in experimental investigations, with results indicating a suppression of Marangoni convection [4]. This is also in agreement with the experimental work of Savino et al [5], where Marangoni convection was measured to be negligible for water droplets. It is therefore of interest to investigate both Marangoni convection as well as the isolated effect of buoyancy on the internal flow in droplets.…”

Section: Introductionsupporting

confidence: 80%

“…Although the theoretical Marangoni effect is significant for the internal flow, the presence of Marangoni convection in water droplets has been challenged [4,5]. To further study this, simulations with and without Marangoni convection are here performed.…”

Section: Internal Flow: Influence From Marangoni Convectionmentioning

confidence: 99%

Heat and mass transfer boundary conditions at the surface of a heated sessile droplet

Ljung

Lundström

2017

Heat Mass Transfer

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This work numerically investigates how the boundary conditions of a heated sessile water droplet should be defined in order to include effects of both ambient and internal flow. Significance of water vapor, Marangoni convection, separate simulations of the external and internal flow, and influence of contact angle throughout drying is studied. The quasisteady simulations are carried out with Computational Fluid Dynamics and conduction, natural convection and Marangoni convection are accounted for inside the droplet. For the studied conditions, a noticeable effect of buoyancy due to evaporation is observed. Hence, the inclusion of moisture increases the maximum velocities in the external flow. Marangoni convection will, in its turn, increase the velocity within the droplet with up to three orders of magnitude. Results furthermore show that the internal and ambient flow can be simulated separately for the conditions studied, and the accuracy is improved if the internal temperature gradient is low, e.g. if Marangoni convection is present. Simultaneous simulations of the domains are however preferred at high plate temperatures if both internal and external flows are dominated by buoyancy and natural convection. The importance of a spatially resolved heat and mass transfer boundary condition is, in its turn, increased if the internal velocity is small or if there is a large variation of the transfer coefficients at the surface. Finally, the results indicate that when the internal convective heat transport is small, a rather constant evaporation rate may be obtained throughout the drying at certain conditions.

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“…[15,16]. More recently, infrared visualization of thermal motion inside evaporating sessile drops of ethanol, methanol and FC-72 onto a heated surface has been investigated [17].…”

Section: Introductionmentioning

confidence: 99%

Onset of Marangoni convection in low viscosity silicon oil inside a heated capillary tube

Buffone

Cecere²,

Savino³

et al. 2014

International Journal of Thermal Sciences

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a b s t r a c tIn the present experimental investigation the onset of Marangoni convection inside a heated capillary tube filled with low viscosity silicon oil is presented and discussed. The 1 cSt viscosity silicon oil used evaporates spontaneously at ambient temperature. The evaporation of silicon oil inside the 1 mm internal diameter tube is not uniform, being larger near the meniscus triple line region than in the centre; this creates gradients of temperatures (which have been measured by InfraRed thermography) and therefore of surface tension. For the unheated tubes this gradient of surface tension is found to be not big enough to set a convection motion (Marangoni convection) which was reported by one of the present authors in previous studies using alcohols. With increasing power supplied to the tube by an electric heater, the Marangoni convection sets in and strengthens at increasing powers till the pinned meniscus detaches from the tube mouth and recedes inside the capillary.

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Buoyancy and Marangoni Effects in an Evaporating Drop

Cited by 89 publications

References 15 publications

Reducing Spatial Heterogeneity of MALDI Samples with Marangoni Flows During Sample Preparation

Reducing Spatial Heterogeneity of MALDI Samples with Marangoni Flows During Sample Preparation

Heat and mass transfer boundary conditions at the surface of a heated sessile droplet

Onset of Marangoni convection in low viscosity silicon oil inside a heated capillary tube

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