On prediction of characteristics for vertical round buoyant jets in stably linear stratified environment

Abstract

A turbulence model is used to study the behaviour of round buoyant jets before the point of neutral buoyancy in stably linear stratified environments. The calculation of the centerline velocity, density, turbulent kinetic energy, half-width of buoyant jets and the profiles of turbulent kinetic energy, turbulent dissipation function, turbulent shear stress and turbulent heat flux are made for a wide range of exit densimetricFroude numbers and ambient temperature stratifications. A unified scaling law is derived for normalization of these results. The correlation of the predicted results shows that the established zone of buoyantjet in the stably linear stratified environment may be divided into three regions: non-buoyant region, intermediate region and plume region. The variation of centerline velocity, density and turbulent kinetic energy and the spread of velocity half-width along the axial line for both uniform and linearly stratified environments for a given exit densimetric Froude number is found to converge to a single curve under the unified scaling law. The profiles of mean velocity, mean temperature and turbulent transport properties are given.