An Experimental Investigation of Streamwise and Vertical Wind Fields on a Typical Three-Dimensional Hill

To study the streamwise and vertical wind fields on a typical three-dimensional hill, wind tunnel tests were performed. The mean values and turbulence intensities of the streamwise and vertical wind speeds of the typical positions above the hill were measured, and they are presented in the form of contour maps for design. Furthermore, the speed-up of the mean wind speeds in the streamwise direction was compared with codes. Finally, the windage yaw of a jumper cable was examined as an example of how to take into account the streamwise and vertical wind field influence on the wind load in the analysis of wind-induced responses. The results show that the most significant speed-up effect in the streamwise direction occurs on the hill crest, and the wind speed-up decreases with the increase of the height. Overall, the wind speed-up along the crosswind center line is larger than that along the along-wind center line of the hill. In the codes, the speed-up effect specified for the structure at half the height of the upstream side of the hill is relatively conservative. With regard to the mean wind speed in the vertical direction, the wind climbing effect located at half the height of the upstream side of the hill is the most significant. The area with the stronger turbulence intensity appears at the foot of the upstream and downstream sides of the hill. The influence of the vertical wind on the jumper cable is remarkable where the wind climbing effect is the most significant, which is worthy of attention in the design of the structure immersed in a hilly terrain-disturbed wind field.