Velocity field measurements in an evaporating sessile droplet by means of micro-PIV technique

Yagodnitsyna, Anna A.; Bilsky, A. V.; Roudgar, Mina; Coninck, J. De; Kabov, Oleg

doi:10.1051/matecconf/20168400042

Cited by 8 publications

(2 citation statements)

References 7 publications

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“…Theoretical predictions [3,[49][50][51] for the free convection velocity inside sessile drop 2 of water or an aqueous solution with a low concentration of another liquid show that the numerical calculation overestimates the velocity value tens of times compared to the experiment [3,52]. Multiple velocity reduction in the experiment is associated with the presence of contaminants in water, which cannot be eliminated [51,53].…”

Section: The Effect Of Surfactants On the Velocity Field Inside Sessile Drop After An Impact Of Another Small Dropletmentioning

confidence: 86%

The Influence of Surfactants, Dynamic and Thermal Factors on Liquid Convection after a Droplet Fall on Another Drop

2020

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The regularities of the processes and characteristics of convection in a sessile drop on a hot wall after the second drop fall are investigated experimentally. The movement of a particle on a drop surface under the action of capillary force and liquid convection is considered. The particle motion is realized by a complex curvilinear trajectory. The fall of droplet with and without surfactant additives is considered. Estimates of the influence of the thermal factor (thermocapillary forces) and the dynamic factor (inertia forces) on convection are given. The scientific novelty of the work is the investigation of the simultaneous influence of several factors that is carried out for the first time. It is shown that in the presence of a temperature jump for the time of about 0.01–0.1 s thermocapillary convection leads to a 7–8 times increase in the mass transfer rate in drop. The relative influence of inertial forces is found to be no more than 5%. The fall of drops with surfactant additives (water + surfactant) reduces the velocity jump inside the sessile drop 2–4 times, compared with the water drop without surfactant. Thermocapillary convection leads to the formation of a stable vortex in the drop. The dynamic factor and surfactant additive lead to the vortex breakdown into many small vortices, which results in the suppression of convection. The obtained results are of great scientific and practical importance for heat transfer enhancement and for the control of heating and evaporation rates.

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Section: The Effect Of Surfactants On the Velocity Field Inside Sessile Drop After An Impact Of Another Small Dropletmentioning

confidence: 86%

The Influence of Surfactants, Dynamic and Thermal Factors on Liquid Convection after a Droplet Fall on Another Drop

2020

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“…Then, the Peclet number Pe may be written in the form Pe = ( u MT + u MC + u a )/ u a = ( Pe С + 1), u C = u MT + u MC (velocity in the liquid due to Marangoni convection), Pe С = ( u MT + u MC )/ u a is the convective Peclet number. As a result of generalization of experimental and calculated data 5 , 28 – 30 , k C = 2.96·10 –10 (m/s), k T = 0.15·10 −7 (m/s). In such formulation, there is no sense in neglecting the inertial terms and considering only the creeping flow, since in the limiting cases we have to obtain a purely conductive heat transfer, when Pe С = 0 ( u C = 0), and vice versa, when Pe С ≫ 1, the number of Pe С shall turn into Re number retaining the power dependence for the laminar flow regime ( n = 0.5).…”

Section: Evaporation and Heat Transfermentioning

confidence: 91%

The influence of characteristic scales of convection on non-isothermal evaporation of a thin liquid layer

Misyura

2018

Sci Rep

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Here, the effect of convection in liquid on non-isothermal evaporation of a horizontal thin layer on a hot wall is investigated. It is considered that the evaporation rate of salts always decreases with the growth of salt concentration. Depending on the nature of evaporation rate, the aqueous salt solutions can be classified into two different types: (1) the equilibrium partial pressure of water vapor ps varies slightly with time; (2) with an increase in salt mass concentration, ps decreases many times, which leads to a sharp drop in evaporation rate j. The criteria for attributing the salt to characteristic types are proposed, and relation between j and thermodynamic properties of salt solutions is determined. Different approaches to modeling are proposed for each group. For the first time, a simple calculation method linking the Peclet and Marangoni criteria with convection in a liquid and non-stationary heat exchange is proposed. The analysis shows that it is impossible to simulate the heat transfer without knowing the local characteristics of the velocity field in the liquid phase and without clearly distinguishing the characteristic convective scales of the velocity and temperature fields. So far, it has been believed that the surface Marangoni flow can be neglected due to the negative impact of surfactants. However, the studies of this paper show that a noticeable increase in free convection relates to the thermal and solutal Marangoni flows. A strong influence of the Marangoni flow on liquid convection at high heat fluxes is extremely important for reliable simulation of layer evaporation in a wide range of modern technologies.

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Interaction of two drops at different temperatures: The role of thermocapillary convection and surfactant

Misyura

Волков

Filatova

2018

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Velocity field measurements in an evaporating sessile droplet by means of micro-PIV technique

Cited by 8 publications

References 7 publications

The Influence of Surfactants, Dynamic and Thermal Factors on Liquid Convection after a Droplet Fall on Another Drop

The Influence of Surfactants, Dynamic and Thermal Factors on Liquid Convection after a Droplet Fall on Another Drop

The influence of characteristic scales of convection on non-isothermal evaporation of a thin liquid layer

Interaction of two drops at different temperatures: The role of thermocapillary convection and surfactant

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