Numerical Simulation of the Lateral Interactions Between Buoyant Clouds

Pairs of buoyant elements, or thermals, are found to merge very rapidly when they are close enough for extensive overlapping of their buoyancy force fields. When this occurs, the merged pair behaves in every respect as a single element with twice the buoyancy of a solitary thermal. In the absence of merging, however, the lateral interaction suppresses the circulation and velocity of rise of both clouds. In addition to these effects, the overlapping buoyancy force field appears to favor coalescence of the clouds, whereas the contacting and interfering fields of toroidal circulation cause a mutual repulsion.