Three-dimensional numerical analysis of bubbly flow around a circular cylinder

A numerical method is developed to simulate a bubbly flow around a circular cylinder using a boundary-fitted coordinate system. In the present study, the number density model of a bubbly flow is employed, where the equations of conservation and the group motion of bubbles are solved directly. The three-dimensional simulations have been conducted under laminar flow conditions for the liquid Reynolds numbers from 100 to 2 000. The void fraction profile behind the cylinder shows good agreement with that of the experiment and another simulation carried out at the liquid Reynolds number of 430. The Strouhal numbers at Reynolds numbers of 200 and 500 are presented. In the lower Reynolds number case, the Strouhal number does not depend on-the variation of the void fraction. On the other hand, the local maximum value of the Strouhal number is observed in the higher Reynolds number case, similar to that observed in the experiment. The bubble accumulation in the Karman vortices is observed in the case of the greater relaxation time of the bubble motion. Such structures have also been observed in the experiment conducted behind a bluff body.