DIMENSIONLESS CORRELATIONS FOR BUOYANT PLUME BEHAVIOR IN CROSS-FLOWS AND SCALING CRITERIA FOR PHYSICAL MODELING OF DISPERSION PROCESSES

Starting from solutions of integral conservation equations governing b uoyant plume behaviour in a neutrally stratified crossflow, dimensionl ess correlations for the trajectory, dilution, and mean concentration of the plume versus distance downwind from the source are derived. Cor relations for trajectory that can be considered extensions of the one- third and two-thirds laws of plume rise are presented, along with a mo re concise correlation that combines the effects of initial buoyancy a nd momentum into a single parameter. By comparing the predictions of t hese correlations with experimental data obtained in a water flume, it is shown that the correlations yield reliable estimates of plume beha viour throughout the initial phase of plume rise. Thus, the equations may be applied with confidence to establish and/or evaluate scaling cr iteria for setting up physical models of dispersion processes in a win d tunnel or water flume. Scaling criteria derived from the dimensionle ss correlations are found to be equivalent to criteria in the wind eng ineering literature for the exact scaling of a model stack. Further, t he dimensionless correlations are shown to be a useful tool in estimat ing scaling errors associated with the various approximate scaling cri teria which must be used in practical model experiments. Dimensionless correlations for plume behaviour and scaling criteria for a stably st ratified crossflow are also briefly discussed.