Influence of buoyancy forces on Marangoni flow instabilities in liquid bridges

The influence of buoyancy forces oscillatory Marangoni flow in liquid bridg es different aspect ratio is investigated by three-dimensional, time-depend ent numerical solutions and by laboratory experiments using a microscale ap paratus, time-dependent numerical solutions system. Liquid bridges heated f rom above and from below, are investigated. The numerical and experimental results show that for each aspect ratio and for, both the heating condition s rite onset of the Marangoni oscillatory flow is characterized by the appe arance of a standing wave regime after a certain time, a second tt transiti on to a travelling wave regime occurs. The three-dimensional flow organizat ional at onset of instability is different according to whether the bridge is heated from above or from below. When the liquid bridge is heated from b elow, the critical Marangoni number is larger, the critical wave number (m) is smaller and the standing wave regime is more stable, compared with the case of the bridge heated from above. For the critical azimuthal wave numbe r, two correlation laws are found as a function of the geometrical aspect r atio A.