The effect of small embankments of wind speeds

Full-scale measurements have been made to determine the increase in wind speed over two exposed embankments, one of 23degree slope and 4.7m in height, the other of 24 degree slope and 7.3m in height. Measurements were made at heights of 5, 10 and 15m above the upper edge of each embankment and at the same heights approximately 100m upwind in the lower-level approach fetch. Despite the modest sizes of the embankments, the maximum recorded increase in mean wind speed was 28% and the minimum was 13%; these increase relate to increases in wind loads on structures erected at the top of the embankments of 64% and 28% respectively. The associated increases in gust speeds are estimated at 33% and 18%, which imply increases in gust loading of 77% and 39% respectively. These experimental results are compared with predictions obtained from a computational fluid dynamics (CFD) analysis, using three high Reynolds number eddy-viscosity models and estimates from the UK wind loading code, BS 6399: Part 2. The CFD results are generally in agreement with the experimental data, although near-ground effects on the embankment crest are poorly reproduced.