HYDRODYNAMIC FORCE BETWEEN SLIGHTLY DEFORMABLE BUBBLES AT LOW-REYNOLDS-NUMBER

A new method is developed to solve the three-dimensional hydrodynamic field generated by multiple bubbles, which are arbitrarily configured at low Reynolds number, taking the effects of both bubble interactions and the slight deformation of the bubble surface into consideration, for the case of epsilon=We/Re<<1. The numerical results for the case o f two equi-radial bubbles confirm the validity of this method with the restriction that the gap between the two bubbles is to be not less th an half of the radius. It is shown that the hydrodynamic force acting as drag is smaller in the case of a bubble moving away from another st ationary bubble than in the case of one bubble approaching another. Th is difference is explained as the nonlinear effect originating from th e bubble surface deformation.