The spread of a negatively buoyant plume in a calm environment

Abstract This paper presents the results of a laboratory experiment to study the spread of a negatively buoyant plume in a calm environment. A semi-empirical analysis is in agreement with the experimental results which indicate that the position of the leading edge of the plume advancing over a horizontal smooth surface is given by r m = (0.84 ± 0.06) (Q 1 g′) 1 4 t 3 4 where Q1g′ is the negative buoyancy flux emanating from the source. Expressions are obtained for conditions under which the effects of wall friction and ambient wind may be neglected. An important physical conclusion is that there is little, if any, mixing between the plume and the environment except at the leading edge.