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- Binh D. Pham (2)
- Hung V. Vu (2)
- Phan H. Nguyen (2)
- Vinh T. Nguyen (2)
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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 ... |
This study presents a front-tracking-based numerical analysis of the forced convection solidification of a sessile droplet on a cooling surface. The droplet, a hollow (or compound) droplet with an encapsulated gas core, undergoes a liquid-to-solid phase change in its shell. This phase change starts from the surface. Meanwhile, the surrounding gas, which is characterized by its Reynolds number Re and temperature, moves toward the droplet parallel to the axis of symmetry. When the temperature of the forced flow is below the solidification value (i.e., cold-forced convection), increasing the strength of the forced flow shortens the solidification process. In contrast, increasing the Re number of a hot-forced convection system prolongs solidification. In other words, an increase in the ... |
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... |
