A buoyant source in the lower of two, homogeneous, stably stratified layers

Abstract

A point source of buoyancy is located at a specified elevation within the lower of two, homogeneous, stably stratified layers. A turbulent buoyant plume is formed above the source, and it impinges on the layers' interface. Depending on the strength of the source, its position below the interface and on the density difference of the two layers, it is conjectured that either: (1) a central portion of the impinging plume flow will penetrate and continue upward into the far field of the upper layer as a buoyant plume, the outer portion of the flow penetrating but then dropping down toward the interface because of negative relative buoyancy; or (2) none of the impinging plume flow will penetrate the upper layer (indepth) because of its being uniformly of negative relative buoyancy. Associated with these possible conditions will be an effective horizontal outflow of fluid at the interface. The paper derives and solves a set of model equations for these plume-interface interactions, and the results are applied to a generic heat transfer problem related to fires in enclosures.