Numerical Simulation of Hot Gas Dispersion from a Chimney

Abstract

This paper reports on numerical simulations of the flow of hot gases released vertically from a chimney into a crosswind with velocity and temperature ratio corresponding to an experiment. The use of a weak compressible scheme, which is capable of taking into account thermal expansion at low Mach number is proposed in order to improve the simulation of the flow. Simulations with 3 different temperature ratios were performed using the proposed method and the incompressible scheme with the Boussinesq approximation. For the isothermal case, both schemes predicted similar trajectories and had good agreement with experimental data. For high temperature ratios, our method showed better agreement with experimental data than the simulations with the method based on the Boussinesq approximation. It was found that the density changes due to thermal expansion near the nozzle exit act against buoyancy, diminishing the vertical velocity over the chimney affecting the trajectory of the flow, also modifying the areas where buoyancy has a considerable effect.