Investigation of a Buoyant Bubble Motion in a Wall-Driven Square Cavity

Direct steam generation is considered as a potential substitute for conventional power generation technologies, for its advantageous characteristics. It can be directly powered by solar radiation by concentrating it on a specific point, besides eliminating heat exchangers and fluid refrigerant, which allows to reduce operating costs. It is crucial, to properly grasp the two-phase flow involved in these technologies. In this paper, we numerically explore the effect of flow strength and wall-driven position on the flow structure and dynamic behavior of bubbles in a square enclosure, through employing the Boltzmann pseudopotential lattice method. The terminal position of the bubble reflects the concurrence between the existing forces. When the value of the Reynolds number exceeds 600, the fluid flow strength overcomes buoyancy and pushes the bubble towards the center of the primary vortex, regardless of the wall-driven configuration. In terms of flow structure, wall-driven flow structures dominate the square cavity in all studied cases. The wall motion configuration affects the bubble trajectory, especially the left wall-driven case where the bubble only reaches the second quarter of the cavity height before being driven toward the center of the primary vortex. Note that the wall configuration has a strong impact on bubble trajectory for equal Reynolds values.