Collision between Small Particle and the Wall in a Two-Dimensional Turbulent Jet Impinging upon the Wall

Abstract

It is the purpose of the paper to investigate how the particles contained in the jet collide with the wall when a two-dimensional turbulent jet issuing from the nozzle impinges upon a wall normally. It is assumed that the interaction between particles is negligible, that the flow field is independent of the existence of the particle and that the particle is subjected to the interaction based on Stokes' drag law in the flow. Under these assumptions, the flow of the turbulent jet is numerically solved by means of the discrete vortex method and particle trajectories are numerically obtained as a function of the aspect ratio (the ratio of the distance between the nozzle and the wall to the nozzle width) and the Stokes number. The particle collision with the wall is divided into two types by the aspect ratio. When the aspect ratio is small, the fluid collides mainly with the wall in the portion of the potential core. Thus the position and the velocity with which particles collide with the wall are nearly identical with those in the case of the laminar jet. When the aspect ratio is large, the position of collision becomes close to the axis of the jet, and the velocity of collision becomes small compared with that of the case of the laminar jet. As the aspect ratio increases, the number of the collision particle decreases.