Two parallel plane jets: comparison of the performance of three turbulencemodels

There have been many investigations in the literature to examine the perfor mance of different turbulence models in predicting flow over backward-facin g steps where the flow is bounded by solid boundaries. However, the evaluat ion of different turbulence models in predicting free shear layers with no solid boundaries, such as two parallel plane jets, is limited. In this pape r, the velocity field of two parallel plane jets with a small nozzle separa tion ratio of s/w = 4.25 determined by laser Doppler anemometry (LDA) is fi rst presented. These experimental results are used to examine the performan ce of three turbulence models (i.e. k-epsilon, RNG k-epsilon and Reynolds s tress) in predicting this flow field. The effects of computational domain s ize, grid resolution and different discretization schemes on the prediction s are discussed. The existence of a recirculation flow region, a merging re gion and a combined region in the two parallel plane jet configuration has been predicted qualitatively by all three turbulence models. On the other h and, quantitative agreement between predictions and measurements varied by as much as 18 per cent for the merging length while the jet spread in the o uter shear layer has been substantially underpredicted by all three models.