In the motion of two gravity-driven bubbles arranged in a line, the trailing bubble is known to accelerate in the wake of the leading bubble. Furthermore, the approaching bubble migrates laterally as a result of bubble–bubble interactions. This paper presents the physical mechanisms for the acceleration and lateral motions of deformable bubbles under stable conditions, i.e., rectilinear motion in a solitary bubble, using numerical simulations. First, the trailing bubble decreases the drag coefficient relative to the case of a spherical bubble as a result of the increased vorticity generated at the leading bubble surface by its deformation. Second, the trailing bubble moves laterally as a result of the shear-induced lift force. In addition, lift reversal occurs in high Bond number cases and very weak lift occurs in low Galilei number cases. Predictions under the assumption of spherical bubbles nearly reproduce the interaction of a pair of deformable bubbles; however, the motion associated with the lift reversal cannot be predicted. Third, the bubbles repel each other as a result of their potential interaction when they are adjacent. This repulsive interaction is due to both the pressure at the surface and the vortex interaction around the bubbles.

在排列成一条线的两个重力驱动气泡的运动中，已知尾随气泡在前气泡之后加速。此外，由于气泡与气泡的相互作用，接近的气泡横向迁移。本文利用数值模拟给出了稳定条件下可变形气泡加速和横向运动的物理机制，即孤立气泡中的直线运动。首先，由于在前气泡表面因其变形而产生的涡旋增加，因此，相对于球形气泡，后气泡减小了阻力系数。其次，由于气泡引起的升力，尾随的气泡横向移动。另外，在邦德数高的情况下发生升力反转，而在伽利略数低的情况下发生升力很弱。在球形气泡假设下的预测几乎再现了一对可变形气泡的相互作用。然而，与升力反向相关的运动无法预测。第三，气泡在相邻时由于其潜在的相互作用而相互排斥。这种排斥性相互作用是由于表面压力和气泡周围的涡旋相互作用所致。