Turbulent jet in confined counterflow

The mean flowfield of a turbulent jet issuing into a confined, uniform counterflow was investigated computationally. Based on dimensional analysis, the jet penetration length was shown to scale with jet-to-counterflow momentum flux ratio. This scaling and the computational results reproduce the well-known correct limit of linear growth of the jet penetration length for the unconfined case when the momentum flux ratio is small. However, for the high momentum flux ratio case corresponding to the confinement, the jet penetration length is shown to reach an asymptotic limit of about 3.57 times the confining duct diameter. This conclusion is contrary to the existing results which predict indefinite growth. A simple modification of an existing similarity solution for the jet in an unconfined counterflow provides a convenient framework for presenting the results of the flowfield and jet penetration length.