Publication Details

Cooper, P. & Hunt, G. (2007). Impinging axisymmetric turbulent fountains. Physics of Fluids, 19 (11), 117101-117101-9.


The behavior of a turbulent fountain that impinges perpendicularly on a horizontal plate a distance H from the fountain origin in a quiescent environment of uniform density is investigated. Images from Light Induced Fluorescence visualization of the flow provide a clear picture of the internal structure of the vertical fountain, impinging radial outflow and the subsequent plume-like flow. For source-plate separations H/Lmo10 the impingement of the fountain results in a buoyant radial wall jet that spreads horizontally before separating from the plate at a radius Rsp. The re-entrainment into the fountain and wall jet of buoyant fluid released on separation leads to the formation of a toroidal vortex of outer radius ~ Rsp. The correlation Rsp/H=0.03(Rirad)-0.75, deduced from theoretical scalings and the results of our experiments, successfully relates the maximum non-dimensional radial spread to the Richardson number Rirad that characterizes the source of the buoyant radial wall jet. The transient development of the flow and influence of the buoyant plume above the impingement zone are discussed.

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