REYNOLDS STRESS DESCRIPTION OF OPPOSED AND IMPINGING TURBULENT JETS .2. AXISYMMETRICAL JETS IMPINGING ON NEARBY WALLS

The flow arising from an axisymmetric turbulent jet with an exit plane in close proximity to the wall against which it impinges is analyzed. The reciprocal of a Reynolds number based on the kinematic viscosity adds here to the two parameters identified in Part I [Phys. Fluids A 5 , 203 (1993)] as determining the flow characteristics of two opposed j ets, namely the ratio of the turbulence scale to the separation of the jet exit from the wall and the ratio of the turbulence intensity to t he mean exit velocity. With all three of these parameters suitably sma ll there is indicated an asymptotic analysis which describes separatel y the flow in three distinct regions. The temperature of the impinging fluid is assumed to be slightly different from that of the wall so th at the mean velocity components, the mean temperature, and the various Reynolds stresses and fluxes vary within a thin wall layer which cons ists of a viscous sublayer and a turbulent shear layer. When the Reyno lds number is suitably high, the sublayer accounts for all of the chan ge in the mean radial velocity and in the mean temperature. The analys is of the turbulence external to the wall layer is compared with exper imental data on a turbulent jet impinging on a wall. Agreement with re spect to the mean axial velocity and the intensities of the axial and radial velocity components is quite satisfactory. Comparison is made w ith experimental data on heat transfer to the wall; the predicted depe ndence of Nusselt number on Reynolds number is confirmed.