Numerical simulation of bubbly flow around two tandem square-section cylinders by vortex method

Abstract

The air—water bubbly flow around two tandem square-section cylinders is simulated with the vortex method proposed by the authors in a prior study. The flow was experimentally investigated by Shakouchi et al. The side length of cylinder s is 30 mm, and the distance between the cylinders is 2s. The water Reynolds number is 10 000, and the air volumetric flow ratio to whole fluid is 0.03. A pair of Karman vortices appear behind the first cylinder. The strength of the Karman vortex downstream of the second cylinder is larger than that for the single-cylinder. The strength of the Karman vortex reduces due to the bubble entrainment. The pressure reduction on the rear surface of the first cylinder is relaxed when compared with that on the single-cylinder. Therefore, the present simulation can predict the reduction of the drag force acting on the first cylinder, which was clarified by the corresponding experimental study.