Buoyant spreading processes in pollutant transport and mixing Part 1: Lateral spreading with ambient current advection

Buoyant spreading phenomena are driven by the buoyant horizontal spreading force that arises from the density difference between the mixed effluent and the surrounding ambient fluid. Such spreading effects, occurring at either water surface, or bottom, or at terminal levels within an ambient density stratification, are significant transport and mixing processes. A model for the lateral buoyant spreading within a currentadvected plume is formulated including several distinct mechanisms: convective spreading with frontal drag effects, interfacial friction, entrainment at the density front, shear flow entrainment, wind-induced entrainment, and surface heat exchange. Also, a criterion, based on a flux Richardson number, has been developed that delineates the transition between the spreading phase and the subsequent passive ambient diffusion regime. The buoyant spreading model is implemented within the Cornell Mixing Zone Expert System (CORMIX). Comparisons with available laboratory and field data support the ...

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