The disturbance effect of a circular cylinder on the diffusion of matter by a plume from a point source in grid-generated turbulence. 1st report Characteristics of velocity and mean concentration field.

Abstract

The effect of the disturbance of a circular cylinder on the diffusion process of dye solution by a non-buoyant plume from a point source in grid-generated water turbulence has been examined experimentally. The cylinder is fixed so that its axis intersects the plume axis perpendicularly at the far downstream location from a source where the plume has developed to have a comparable width with the cylinder diameter. In this paper, the experimental results concerning the mean concentration field are presented. It is found that the vertical profiles of the mean concentration behind the cylinder show flatter shapes, and the profile's half width grows downstream more rapidly than those without the cylinder. These characteristics are apparently caused by the disturbance effect of the cylinder. The vertical and horizontal profiles of the mean concentration appear to be nearly similar at various downstream locations beyond about 20 diameters from the cylinder.