Bubble migration in a vibrating zero gravity environment is numerically investigated using ANSYS-FLUENT software. A 3D CFD model is developed describing the two-phase ow of a nitrogen bubble immersed in a container full of ethanol. The Volume of Fluid (VOF) method and the geometric reconstruction scheme are used to track the liquid-liquid interface. The container is vibrated horizontally with different frequencies from 0 Hz to 1 Hz, and amplitudes from 0.005 m/s 2 to 0.1 m/s 2 . The vibration impact on the bubble arrival times to the top and its ensuing dynamic is analyzed. Different bubble trajectory shapes are observed, other than the conventional vertical translation induced by the temperature difference. Compared to the no vibration case, the bubble motion is slightly either accelerated or decelerated for very low vibration amplitudes, A b = 0.005 m/s 2 . For a xed frequency f = 1 Hz, the bubble arrival time increases signi cantly with the vibration amplitude increment relative to the no vibration case. The vibration effect becomes more intense with the Marangoni number decrease when f = 0.2 Hz and A b = 0.005 m/s 2 . Those results are di cult to obtain experimentally, signifying the importance of this numerical study to understand bubble motion and migration in space.
The influence of two isothermal blocks placed in a low position m 0.18π in a cylindrical heat exchanger is numerically studied. The governing equations are discretized by the centered finite difference method using the ADI scheme. By varying Rayleigh number range between 1000 and 10000, we are interested in the local Nusselt number and the local efficiency variations as a function of the angular coordinate . In one hand, we found that heat transfer is important in the superior zone of the annulus for high Ra and in the central zone for low Ra. On the other hand, compared to the without blocks configuration, heat transfer in the inferior and central zones is improved for all Ra.
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