Large eddy simulation of spatially developing isothermal and buoyant jets

This paper presents an application of large-eddy simulation (LES) to spatially developing isothermal and buoyant jets. The numerical method is based on the predictor-corrector approach for low Mach number compressible flows. The Adams-Bashforth scheme is used for time marching integration and a QUICK difference is used for space discretization on a staggered grid for the 3D Navier-Stokes equations. As a test case, a turbulent isothermal jet is calculated to compare with available experimental data and good agreement has been achieved. The main part of this paper is a study of buoyant jets. The dynamic phenomena of puffing and formation of large vortex structures are well captured by the present simulation. The pulsation Frequencies of buoyant plumes compare well with the experimental results of Cetegen et. al. for different Froude numbers and density ratios. Comparisons have also been carried out between the results of a DNS and the present LES and good agreement has been reached. Some statistical quantities and different terms in the vorticity equation are analyzed.