Bubble rise under an inclined plate

We extend existing measurements of bubble rise velocity or, equivalently, drag in the spherical-cap regime to include the effects of rise under an inclined plate which both changes the bubble shape and the effective buoyancy force in the direction of bubble motion. As found previously for rise in inclined tubes for example (Zukoski 1966) there is an angle of inclination for which the rise velocity is a maximum. We propose, also, an inviscid model that appears to describe the results adequately, as is the case for the spherical-cap regime in an extended fluid (Davies & Taylor 1950).