On the Dynamics of Environmental Pollution: Simulation of the near Field of a Jet in Crossflow

This paper investigates numerically the complex flow in the near field of a rectangular jet discharging vertically downward into a uniform crossflow. This flow situation exists when pollutants generated from many industrial processes are released into the environment. Examples include those released from petrochemical plants, power plants, and desalination units. A thorough understating of turbulent dispersion of such pollutants is a first step towards the development of appropriate control methods. Using general purpose Computational Fluid Dynamics (CFD) software, the turbulent Navier-Stokes equations for unsteady, three-dimensional, incompressible flows are numerically solved in this study. The accuracy of this computational software is assessed by comparing the computed results with Laser Doppler Anemometry (LDA) measurements for two flow cases. Both cases (jet-to-crossflow velocity ratios 3 and 5) yield favorable agreement for the turbulence characteristics of the flow. The present computational methodology not only allows us to capture the coherent structures of the flowfield which include tornado-like vortices, counter-rotating vortices, and a horseshoe-type vortex, but also helps in understanding the mixing processes of pollutants with the ambient. This, in turn, may help in the utilization, enhancement, or suppression of selected vortices in many environmental pollution problems.