DYNAMICS OF A BUBBLE RISING ON THE VICINITY OF A VERTICAL WALL

An experimental and numerical study on the dynamics of an air bubble rising close of a vertical wall is presented. The problem is characterized by three dimensionless numbers, namely Galileo (Ga), Bond (Bo), and the dimensionless distance between the bubble and the wall, L*. Bubbles are injected in a glass tank 120 cm high with a 15 x 15 cm² cross-section. To vary the control parameters, different liquids and air injectors were employed, and a mobile wall inside the tank let us precisely control L*. We focus on three regimes at high Bo that exhibit different ascending trajectories, i.e. rectilinear, spiral and planar zig-zag. The experiments were recorded with two high-speed cameras moved vertically by a controlled linear motor. The images were processed to obtain the bubble contour, deformation and trajectory. Moreover, unsteady, three-dimensional, incompressible, two-phase flow simulations were performed using Basilisk and spatial Adaptive Mesh Refinement (AMR) technique. The forces acting on the bubbles were obtained, being associated to the bubbles’ dynamics and the topology of the bubbles’ wakes. The study will allow us to determine the effect of a vertical wall on the phase diagram, in the (Bo, Ga) plane, defining the different styles of path exhibited by the bubbles.