Wind Tunnel Tests of Effects of Atmospheric Stability on Turbulence Flow Over a Three-dimensional Hill

摘要

This study is on the turbulence structure of the airflow around a three-dimensional hill model placed in a boundary-layer flow. The effect of atmospheric stability on the diffusion field of the boundary layer is examined. The wind velocity is measured with a three-dimensional Laser Doppler Anemometer (LDA). The main results are as follows: 1) The mean wind velocity does not vary with the stability at the hilltop; it reaches a maximum at the back of the hill, for the unstable case. 2) The turbulence velocity at the back of the hill reaches its peak value at the height of the hilltop. It takes maximum value for the stable boundary-layer flow, and becomes smaller for the neutral flow and the unstable flow. Buoyancy production has little effect on the production of turbulence energy.