A new turbulence model for the axisymmetric plume

A new turbulence model has been proposed for the axisymmetric plume. In this model the equations for the turbulent kinetic energy (k), its dissipation $(\varepsilon)$, temperature fluctuations $\overline{(t^{'2})}$, and intermittency $(\gamma)$ have been solved. The equation for the dissipation $(\varepsilon)$ accounts for the effect of entrainment, which in turn requires the solution of a transport equation for the intermittency. The effect of buoyancy on Reynolds stress and radial heat flux has been modelled by the algebraic stress model (ASM). For the buoyancy production of turbulent kinetic energy a simple model (which assumes it to be proportional to $\sqrt{k\overline{t^'2}}$) has been used. A detailed comparison of the predictions has been made with measurements. The present $k - \varepsilon - \overline{t^{'2}} - \gamma$ model is shown to simulate accurately the intermittency and the effects of buoyancy on mean and turbulent quantities