Rise velocity of a spherical cap bubble By DANIEL

where R = D/2 is the radius of the cap, ρ and ν are the density and kinematic viscosity of the liquid, σ is surface tension, r(θ) = R(1 + sθ) and s = r ′′(0)/D is the deviation of the free surface from perfect sphericity r(θ) = R near the stagnation point θ = 0. The bubble nose is more pointed when s < 0 and blunted when s > 0. A more pointed bubble increases the rise velocity; the blunter bubble rises slower. The Davies & Taylor (1950) result arises when s and ν vanish; if s alone is zero,