Turbulent diffusion behind a heated line source in a nearly homogeneous turbulent shear flow

The turbulent diffusion of heat from a line source has been examined in a nearly homogeneous turbulent shear flow with a uniform mean velocity gradient. Mean shear was generated in a wind tunnel using an array of parallel channels of transversely varying porosity. The dimensionless intensity of temperature fluctuations was found to drop fast at large distances from the source in agreement with the numerical predictions of a Lagrangian random walk model. Thus, it is confirmed that shear tends to reduce the intensity of concentration fluctuations. 21 references