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TL;DR: "Some calculations suggested that the bubble is surrounded by an extremely thin layer of liquid touching the sides of the tube, which slowly diminishes
by xchip 7y ago
TL;DR:
"Some calculations suggested that the bubble is surrounded by an extremely thin layer of liquid touching the sides of the tube, which slowly diminishes in size and eventually disappears, Kolinski said. That thin layer would create resistance to the motion of the bubble as it tries to rise."
- abstractbeliefs 7y agoBut actually they disproved this belief: 'The researchers indeed observed this very thin layer around the gas bubble and measured it to be about 1 nanometer thick. That's what quenches the movement of the bubble as theoretical work had predicted. But they also found that the liquid layer (which forms because the pressure in the gas bubble pushes against the walls of the tube) doesn't disappear, but rather stays at a constant thickness at all times. Based on their measurements of the thin layer of fluid, they were also able to calculate its velocity. They found that the gas bubble isn't stuck at all but is rather moving "extraordinarily slowly," at a pace invisible to the naked eye'
- londons_explore 7y agoThere is also evaporation occurring on the top surface of the gas bubble, and condensation happening on the bottom. Since there is a small pressure differential, there will be a net upwards movement. It's a small effect, but it might dominate.