Prediction of secondary vortex flowfields induced by multiple free-jets issuing in close proximity

A continuity-constraint finite element numerical algorithm, for solution of the three-dimensional parabolic Navier-Stokes equations for subsonic turbulent flows, is applied to prediction of secondary vortex flowfields induced by multiple free-jets issuing in close proximity. The combined action of axial decay of the high speed jets, induced entrainment from the farfield, and geometric discreteness of the jets yields prediction of eight counter-rotating vortex pairs for a four-jet configuration. The extremum magnitude of the induced transverse vortex velocity can exceed 10% of that of the jet initial axial velocity. The results of the numerical predictions compare well with available video-graphic data, including the effects of geometric and initial flowfield modifications.