At what velocity do bubbles rise to the surface?

The velocity will depend on the Buoyancy force. This force tells you the acceleration at which the bubbles will rise to the surface (provided they're not too big to break into smaller bubbles). read more

An air bubble in water will rise much faster than an oil bubble in water. The primary resistance is the viscosity of the fluid. Bubbles will rise faster in water than in honey. The size of the bubble has complicated effects. A large bubble will rise faster than a small bubble, but it is not linear. read more

1.3 Motion and Velocity of Bubbles The regime of bubble motion varies considerably with the Reynolds number, Re = Ua γ (3) where U = bubble rise velocity a = bubble radius γ = kinematic viscosity of fluid 1. For Re < 1 a < 0.01 cm Stokes Law Regime 1ga2 U 3 ⎛⎞ = ⎜ ⎜γ ⎝⎠ ⎟ ⎟ (4) where g is the gravity constant. Bubbles rise vertically without oscillating. 2. read more

velocity of long bubbles in round pipes (Wallis 1969; Vania et al. 2002). It is of interest to consider different effects entering into the formula for the rise velocity U given by (1.22). read more

In fact, the bubble will expand (as the hydrostatic pressure decreases as the bubble gets closer to the surface) so this force will increase as the bubble approaches the surface drag. Depending on the Reynolds number of the flow (laminar or turbulent) this force will either scale linearly, or quadratically, with velocity. read more