Investigation of characteristic scales in variable density turbulent jets using a second‐order model

This paper is concerned with the investigation of characteristic turbulent scales in circular and plane turbulent free jets with large density variations. The numerical study has been performed with a second‐order turbulence model to confirm analytical relations about density and Reynolds number effects on dynamic and scalar turbulence scales derived from requirements of pseudo‐self‐preservation. The present results explain and quantify trends previously reported from visualizations of variable density turbulent jets performed by Pitts (NBSIR Report No. 86‐3340, U.S. Department of Commerce, 1986). It is clearly shown that the parameter relevant for the evolution of these scales is the momentum flux M j . In addition, the influence of this quantity on small scales is found to be larger than that on large scales.