We investigate the dynamics of a millimetre-sized air bubble rising in a liquid due to buoyancy under the influence of a magnetic field applied in a direction transverse to the bubble motion by conducting three-dimensional numerical simulations. The path and trajectory of the air bubble are examined by varying the strength of the transverse magnetic field. In the absence of a magnetic field, it is well known that under certain conditions a tiny air bubble undergoes spiralling motion due to its shape deformation and vortex shedding in the wake region. It is shown here that the spiralling motion of an air bubble observed without magnetic field transforms into a purely zigzagging motion under an applied transverse magnetic field. To understand the mechanism, we analyse the evolution of the wake vortices and forces experienced by the bubble in the presence of a transverse magnetic field. It is found that the twisted double-threaded vortices observed in a spiralling bubble in the absence of a magnetic field appear to rotate perpendicularly to the applied magnetic field across the vertical axis, thereby making the bubble shift its trajectory from spiralling to zigzagging. By calculating the lift and drag forces acting on the bubble, it is shown that how these forces acting on the bubble contribute to the vortex shedding patterns. Thus, the present study demonstrates the mechanism to control the trajectory of an air bubble under the application of a magnetic field.

通过进行三维数值模拟，我们研究了由于在垂直于气泡运动的方向上施加的磁场的影响下，由于浮力而在液体中上升的毫米大小气泡的动力学。通过改变横向磁场的强度来检查气泡的路径和轨迹。在没有磁场的情况下，众所周知的是，在一定条件下，微小气泡由于其形状变形和在尾流区域的涡旋脱落而经历螺旋运动。在此示出，在没有施加磁场的情况下观察到的气泡的螺旋运动在施加的横向磁场下转变为纯之字形运动。要了解机制，我们分析了在横向磁场存在下尾流涡流和气泡所受力的演变。发现在没有磁场的情况下在螺旋形气泡中观察到的扭曲双螺纹涡流似乎垂直于所施加的磁场沿垂直轴旋转，从而使气泡的轨迹从螺旋形变为锯齿形。通过计算作用在气泡上的升力和阻力，表明了作用在气泡上的这些力如何促进涡旋脱落模式。因此，本研究证明了在磁场作用下控制气泡轨迹的机理。发现在没有磁场的情况下在螺旋气泡中观察到的扭曲双螺纹涡流似乎垂直于所施加的磁场沿垂直轴旋转，从而使气泡的轨迹从螺旋移动到曲折。通过计算作用在气泡上的升力和阻力，表明了作用在气泡上的这些力如何促进涡旋脱落模式。因此，本研究证明了在磁场作用下控制气泡轨迹的机理。发现在没有磁场的情况下在螺旋气泡中观察到的扭曲双螺纹涡流似乎垂直于所施加的磁场沿垂直轴旋转，从而使气泡的轨迹从螺旋移动到曲折。通过计算作用在气泡上的升力和阻力，表明了作用在气泡上的这些力如何促进涡旋脱落模式。因此，本研究证明了在磁场作用下控制气泡轨迹的机理。结果表明，作用在气泡上的这些力如何促进涡旋脱落模式。因此，本研究证明了在磁场作用下控制气泡轨迹的机理。结果表明，作用在气泡上的这些力如何促进涡旋脱落模式。因此，本研究证明了在磁场作用下控制气泡轨迹的机理。