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- Binh D. Pham (3)
- Hoe D. Nguyen (3)
- Hung V. Vu (3)
- Phan H. Nguyen (3)
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- Compound droplet (2)
- Front-tracking (2)
- Constriction (1)
- Droplet (1)
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Compound and simple droplets have been studied and appeared in many life applications, e.g., drug processing and microfluidic systems. Many studies have been conducted on the thermocapillary effects on simple droplets, but similar studies on compound droplets are quite rare. Filling this missing gap, this paper presents the front-tracking-based simulation results of the thermocapillary effects on compound droplets in a certain limited domain. The compound droplet consists of a single inner core that is initially concentric with the outer one. Various dimensionless parameters including Reynolds number from 1 to 50, Marangoni number from 1 to 100, droplet radius ratio from 0.3 to 0.8, and viscosity ratios from 0.1 to 6.4 are varied to reveal their influences on the migration of a comp... |
In this paper, we numerically investigate the dynamics of a compound droplet driven by surface tension variation induced by a thermal gradient in a sinusoidal constriction tube. Initially, the compound droplet with a concentric inner core is spherical and placed in the constriction's upstream region at a low temperature. As time progresses, it migrates downstream with a high temperature. Due to the constriction, the droplet is slowed down in the upstream region and accelerated again right after passing the constriction. This acceleration maximizes the eccentricity. However, the constriction results in an increase in the maximum eccentricity when increasing its depth to a value corresponding to the size of the tube neck, which is greater than or equal to the droplet size. Effects of ... |
In this study, the solidification process of a compound droplet is numerically simulated by an axisymmetric front-tracking/finite difference technique. The compound droplet placed on a cold flat surface in a gas environment consists of an inner gas core surrounded by a concentric shell phase-change liquid that forms an outer droplet. The initial droplet shape assumed as a spherical cap is therefore determined by two wetting angles known as the inner wetting angle (?0i for the inner core) and the outer wetting angle (?0o for the outer droplet). During the solidification process, there is the presence of two three-junction points where a prescribed growth angle ? is specified. We analyze the solidification process undergoing the influence of the geometrical aspects of the compound dro... |
The present paper focuses on the motion due to the thermocapillary force of a droplet in a circular tube through the front-tracking-based simulation. The tube profile in the axial direction is generated with a sinusoidal function that induces a constriction with depth d at the middle. The droplet is slowed down as it migrates from the cold region (ahead of the constriction) to the hot region in the downstream. Various parameters including the Marangoni number Ma, the capillary number Ca and the depth of the constriction d are varied to better understand the thermocapillary motion of the droplet under the influence of the constriction. The simulation results show that when the Ma number increases, the influence factor of the constriction increases and the migration velocity of the dr... |
