用PIV方法研究底面粗糙度对类鱼雷形涡的影响

The flow field of a laboratory-simulated tornado was studied by means of 2-D Particle Image Velocimetry or PIV technique with the purpose of investigating the effects of roughness on the near-ground tornado-like vortex structure and its velocity distribution. The results show the flow regime transition from multi-celled vortices over the smooth surface at a higher swirl ratio to singleor dual-celled vortices with roughness. Significant difference in velocities and turbulence characteristics is observed as a result of increasing ground roughness. This work is part of a project that seeks better understanding of the near-ground flow field and resulting wind-induced loads on structures in a tornado.