Numerical investigation of the inlet flow conditions on a turbulent square free jet

In this study, an incompressible, turbulent, free jet of air issuing from a sharp- edged square slot or nozzle is numerically investigated using a standard k-ԑ turbulence model. The system of equations governing the studied configuration are solved with a finite volume scheme using a staggered grid, which is uniform in the three directions of the flow. Due to the sharp -edged in the outlet of the square nozzle, the correct behavior of the jet at the inlet of the jet chamber is complex. Therefore, in this simulation, an attempt has been made (by applying appropriate boundary conditions such as the type of inlet velocity profile, and inlet turbulence intensity distribution) to consider the effects of the sharp- edged more accurately. The results of this work have been validated and compared with the experimental results of the same case. This comparison shows that by selecting the uniform velocity profile for the inlet boundary condition, the decay of the mean streamwise velocity on the centerline of the jet differed greatly from the experimental results. Therefore, when the inlet uniform velocity profile is used, the jet dispersion along the jet chamber is not truly simulated. As a solution for this problem, we corrected the Y1/2 (jet half-velocity width in the Y-direction) near the nozzle output by applying a parabolic inlet velocity profile and setting the inlet streamwise turbulence intensity equal to 5%, which caused the jet dispersion to be well simulated along the jet chamber compared with the experimental data.