Migration and Adherence of Oil Droplets on Surfaces with Different Wettability in a Laminar Flow Field

Wang²,

et al. 2020

Langmuir

Self Cite

In this aticle, the continuous movement patterns and characteristic parameters of oil droplets on surfaces with different wettability immersed in a laminar flow field were observed, and the change rules of the geometric parameters of oil droplets under different experimental conditions were obtained. Then, the factors influencing the continuous moving behaviors of the oil droplets were analyzed, and the continuous movement velocity of the oil droplets under different experimental conditions was demonstrated. On this basis, the change law of the continuous movement velocity of oil droplets with the flow velocity was discussed. In addition, the coupling effect of the oil drops’ height, surface properties, and water flow velocity on the continuous movement of oil droplets was studied, and the critical conditions for the continuous movement were obtained. According to the critical conditions, the mathematical model which described the law of continuous motion of the oil droplets adhered on surfaces with different wettability in the laminar flow field was established. The quantitative relationships among the average continuous moving velocity of oil droplets, physical properties, geometric parameters, water flow velocity, and surface wettability were obtained, which defined the necessary conditions for the uniform and accelerated movement of oil droplets, providing an important basis for choices of suitable surface wettability and flow field conditions in practical engineering applications.

Section: ■ Experimental Results and Analysismentioning

confidence: 99%

Section: ■ Experimental Setup and Methodsmentioning

confidence: 99%

Section: Experimental Setup and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Continuous Movement Mechanism of Oil Droplets Adhered on Surfaces with Different Wettability in the Flow Field

Wang²,

et al. 2020

Langmuir

Self Cite

“…The droplet velocity was shown to increase with increasing the wettability gradient. Han et al , concentrated on oil droplets spreading on the surface with a superoleophilic–superoleophobic wettability gradient, establishing a mathematical model to analyze water film thinning and adherence of oil droplets on the wall in the laminar flow field through stress analysis and obtaining a quantitative relation among droplet parameters through energy analysis. From the above literature, it is clear that most studies about droplet impact on a hybrid-wettability surface are focused on droplet movement distance.…”

Section: Introductionmentioning

confidence: 99%

Droplet Wetting Propagation on a Hybrid-Wettability Surface

Wang

Liang

et al. 2021

Langmuir

Droplet impinging on the boundary between hydrophilic and hydrophobic regions of a hybrid-wettability surface is studied both experimentally and numerically in the present paper. The interfacial evolution and dynamic feature and the corresponding underlying mechanisms behind are mainly analyzed. Because of the unbalanced surface energy in the vicinity of a boundary, the droplet undergoes spreading−receding in the hydrophobic region before migration toward the hydrophilic region. This results in an increase first but then a decrease in the spreading factor in the hydrophobic region, while it increases continuously in the hydrophilic region. In addition, increasing Weber number leads to the increase in both the spreading factor and migration displacement of the droplet in the hydrophobic region, but the latter decreases in the hydrophilic region, resulting from different momentums of secondary spreading. The experimental determinations are verified in detail by a series of numerical simulations performed based on the single variable method by fixing contact angles in different regions separately and excluding the impact momentum. It is shown that the highly unsymmetrical pressure field is exactly one important reason for droplet migration on the hybrid-wettability surface. Despite the weak dependence of the spreading factor on the hydrophilic contact angle in the hydrophobic region, it has an appreciably positive effect on droplet migration, which is confirmed by the increased pressure gradient with its action area in the hydrophobic region when decreasing the hydrophilic contact angle. This paper advances the fundamental understanding for droplet migration on the hybrid-/gradient-wettability surface.

Asia-Pacific J Chem Eng

Enhancement in kerosene droplet–coal particle collision and adsorption by bubble trailing vortex in coal slurry conditioning: Energy evolution of collision process

Zhu,

Qin,

Chen

et al. 2024

Understanding the collision between kerosene droplets and coal particles in the bubble trailing vortex region is crucial for enhancing slurry conditioning. We found the area of the bubble trailing vortex region increased as the bubble size increased via the Fluent 6.3.26 software. A kerosene droplet velocity range of 0.074–0.106 m/s and a coal particle velocity range of 0.062–0.104 m/s were obtained if a bubble had a diameter of 0.3 mm. We employed a high‐speed motion acquisition system and observed the collision process, which was divided into two stages: Compression and Rebound. The critical motion distance increased as the kerosene droplet size increased, and sufficient kerosene droplet motion distance and enough kinetic energy normally resulted in a rebound phenomenon. The attenuation energy was almost positively linear to the initial energy, and the energy attenuation coefficient of the collision process was fitted to 0.626. Our results can provide valuable insight into mineral separation.