Direct numerical simulation of three-dimensional Navier Stokes equations for slit nozzle free jets and experimental verification. 1st Report, Velocity vector diagrams and mean velocity distributions.

Abstract

The third-order upwind finite difference scheme is used for the convective terms in three-dimensional Navier-Stokes equations to simulate directly the free jet flow issuing from a slit nozzle. The calculated flow field ranges from the nozzle exit to the fully developed turbulent region. The kinetic energy conservation scheme is also devised for the convective terms. The calculated results of mean velocity distributions and velocity vector diagrams are compared with the experimental data. The mesh width is roughly ten times Kolmogorov microscale; however, the mean velocity distributions in the free jet are in fairly good agreement with the experimental data. This is because the simulation well represents the motion of large-scale eddies which play an important role in a flow field formation. Hence the neglection of the small-scale eddies in the third-order upwind finite difference scheme does not largely affect the simulation of large-scale eddies.