Session Ca - Turbulent Jets & Wakes.
ORAL session, Sunday, November 23
301, Moscone Center
A numerical study of compressible plane jets exhausting into a parallel stream is extended to three dimensions. Previous two-dimensional simulations have demonstrated that the inviscid, spatially evolving model is capable of capturing the correct spreading and decay in the mean streamwise velocity field of a nearly incompressible jet. The cases have also shown that the approximately self-similar mean velocity profile is unaffected by increasing compressibility, as measured by the convective Mach number M_c, but that the mean normal entrainment velocity is essentially shut off at low to moderate compressibility (M_c \leq 0.4). The present computations examine one identical case, but in three dimensions, to assess the validity of the earlier computations in considering only the two-dimensional dynamics. Examination is made of the velocity fluctuation statistics to determine if the present inviscid model, which captures only the large scale mixing, is capable of revealing this free shear flow's turbulence structure. Additionally, three-dimensional simulations allow extension of the study to higher convective Mach numbers (M_c \geq 0.6), at which smaller-scale oblique, three-dimensional structures dominate in strength over the two-dimensional spanwise vortex rollers.