Improved predictions of the flow field in submerged and confined impinging jets using the Reynolds stress model

The flow field of a normally impinging, axisymmetric, confined and submerged liquid jet is predicted using the Reynolds stress turbulence closure model in the FLUENT finite-volume code. The results are compared with experimental measurements and flow visualizations, and are used to describe the position of the recirculating toroid in the outflow region which is characteristic of the confined flow field. Changes in the recirculation pattern features due to changes in Reynolds number, nozzle diameter and nozzle-to-target plate spacing are documented. Results are presented for nozzle diameters of 3.18 and 6.35 mm, jet Reynolds numbers in the 2000-23000 range, and nozzle-to-target plate spacings of 2, 3, and 4 jet diameters. Up to three interacting vortical structures are predicted in the confinement region at the smaller Reynolds numbers. The primary recirculation pattern center moves away from the jet center line with an increase in Reynolds number, nozzle diameter, and nozzle-to-target plate spacing. Computed flow patterns were in very good qualitative agreement with experiments. The radial location of the primary toroid center was predicted to within ±40% and ±3% of the experimental position for Re=2000-4000 and Re=8500-23000, respectively. The jet center line velocity after the nozzle exit was computed with an average error of 6%. Reasons for the differences between the numerical predictions at Re=2000-4000 and experiments are discussed. Flow field predictions using the standard high-Reynolds number k-ε and renormalization group theory (RNG) k-ε models are shown to be inferior to Reynolds stress model predictions