Bubble shapes in nucleate boiling

Abstract

AbstractAn attempt is made to explain the differently shaped bubbles observed growing on a surface during nucleate boiling of water. Some of the bubbles photographed were very close to the spherical shape, while others were close to the hemispherical. Also, a number of bubbles had intermediate shapes and were called oblate bubbles.Measurements of bubble dimensions and growth rates obtained from high‐speed films were analyzed. By using a modified Rayleigh equation, the relative importance of the inertial and surface tension forces was computed. it appeared that the differences in shapes among bubbles can be explained on the basis of the relative importance of these forces.It was found that for spherical bubbles inertial forces are small because of the slow growth rate and surface tension is clearly the dominant force. For hemispherical bubbles, however, the fast growth rate causes a very large inertial force which is greater than surface tension. For the oblate bubbles neither of the forces was found to be dominate and inertia as well as surface tension determines the shape.