Evaporation-induced flow around a droplet in different gases
TL;DR: In this article, the influence of the ambient gas on the evaporation induced flow around a droplet at atmospheric conditions was investigated, and it was shown that the evapse-induced flow in these gases for different liquids was measured using particle image velocimetry.
Abstract: It is known from recent studies that evaporation induces flow around a droplet at atmospheric conditions. This flow is visible even for slowly evaporating liquids like water. In the present study, we investigate the influence of the ambient gas on the evaporating droplet. We observe from the experiments that the rate of evaporation at atmospheric temperature and pressure decreases in a heavier ambient gas. The evaporation-induced flow in these gases for different liquids is measured using particle image velocimetry and found to be very different from each other. However, the width of the disturbed zone around the droplet is seen to be independent of the evaporating liquid and the size of the needle (for the range of needle diameters studied), and only depends on the ambient gas used.It is known from recent studies that evaporation induces flow around a droplet at atmospheric conditions. This flow is visible even for slowly evaporating liquids like water. In the present study, we investigate the influence of the ambient gas on the evaporating droplet. We observe from the experiments that the rate of evaporation at atmospheric temperature and pressure decreases in a heavier ambient gas. The evaporation-induced flow in these gases for different liquids is measured using particle image velocimetry and found to be very different from each other. However, the width of the disturbed zone around the droplet is seen to be independent of the evaporating liquid and the size of the needle (for the range of needle diameters studied), and only depends on the ambient gas used.
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TL;DR: In this article, a direct experimental observation of convective flow inside rapidly evaporating droplets has been carried out, and the possible causes of such a flow are also explored, as well as possible causes for the quiescence of the surrounding gas around the evaporation.
Abstract: Studies on the evaporation of suspended microlitre droplets under atmospheric conditions have observed faster evaporation rates than the theoretical diffusion-driven rate, especially for rapidly evaporating droplets such as ethanol. Convective flow inside rapidly evaporating droplets has also been reported in the literature. The surrounding gas around the evaporating droplet has, however, been considered to be quiescent in many studies, the validity of which can be questioned. In the present work, we try to answer this question by direct experimental observation of the flow. The possible causes of such a flow are also explored.
42 citations
TL;DR: In this article, the relative influences of diffusion and buoyancy-induced convection of the vapors on the evaporation rate of liquid hydrocarbons were studied in order to better understand the relative influence of diffusion.
38 citations
18 May 2017
TL;DR: In this paper, the authors investigate the evaporation of liquid disks in the presence of natural convection due to a density difference between the vapor and the surrounding gas, and derive scaling laws to describe the evapse rate.
Abstract: We investigate theoretically and experimentally the evaporation of liquid disks in the presence of natural convection due to a density difference between the vapor and the surrounding gas. From the analogy between thermal convection above a heated disk and our system, we derive scaling laws to describe the evaporation rate. The local evaporation rate depends on the presence of a boundary layer in the gas phase such that the total evaporation rate is given by a combination of different scaling contributions, which reflect the structure of the boundary layer. We compare our theoretical predictions to experiments performed with water in an environment controlled in humidity, which validate our approach.
28 citations
TL;DR: By dual-spacecraft observations, a solar wind reconnection with clear Hall magnetic fields is reported, showing direct evidence for kinetic effects that dominate the collisionless reconnection.
Abstract: Kinetic effects resulting from the two-fluid physics play a crucial role in the fast collisionless reconnection, which is a process to explosively release massive energy stored in magnetic fields in space and astrophysical plasmas. In-situ observations in the Earth's magnetosphere provide solid consistence with theoretical models on the point that kinetic effects are required in the collisionless reconnection. However, all the observations associated with solar wind reconnection have been analyzed in the context of magnetohydrodynamics (MHD) although a lot of solar wind reconnection exhausts have been reported. Because of the absence of kinetic effects and substantial heating, whether the reconnections are still ongoing when they are detected in the solar wind remains unknown. Here, by dual-spacecraft observations, we report a solar wind reconnection with clear Hall magnetic fields. Its corresponding Alfvenic electron outflow jet, derived from the decouple between ions and electrons, is identified, showing direct evidence for kinetic effects that dominate the collisionless reconnection. The turbulence associated with the exhaust is a kind of background solar wind turbulence, implying that the reconnection generated turbulence has not much developed.
27 citations
TL;DR: L'evaporation d'une goutte sessile de differents liquides (eau, toluene, methanol, ether de diethyle) par 2 interferometres simultanement.
Abstract: L'evaporation d'une goutte sessile de differents liquides (eau, toluene, methanol, ether de diethyle) par 2 interferometres simultanement
21 citations