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ISSN Online: 2377-424X

ISBN Print: 0-89116-299-2

International Heat Transfer Conference 7
September, 6-10, 1982, Munich, Germany

LATERAL AND LONGITUDINAL TURBULENT DIFFUSION OF SCALAR QUANTITIES IN THERMALLY STRATIFIED FLOW IN AN OPEN CHANNEL

Get access (open in a dialog) DOI: 10.1615/IHTC7.880
pages 431-436

要約

Buoyancy effects on the lateral and longitudinal diffusion of scalar quantities (heat and mass) were investigated in thermally stratified flow in an open channel under stable, unstable and neutral conditions. Lateral and longitudinal eddy diffu-sivities were directly calculated from the turbulent mass- and heat-fluxes obtained from measurements of velocity, concentration and temperature fluctuations. The results show that lateral and longitudinal diffusion, as well as vertical diffusion, of the scalar quantities is suppressed under stable conditions and enhanced under unstable conditions. Vertical diffusion is most strongly affected by buoyancy; lateral diffusion less so and longitudinal diffusion is least dependent on buoyancy. Each of the eddy diffusivities is well-correlated with the local gradient Richardson number and their empirical relations are presented. A theoretical spectral equation model, applicable to stratified flows, was well compared with the experimental results.