Forest Edge Representation in Scaled Experiments: A Flexible Approach for Matching to Field Observations

We present a flexible solution for the representation of forest edges in windtunnel experiments that can be easily adapted to match observed wind statistics from fullscale field experiments. The solution is based on an incremental approach in which layers of coarse mesh are wrapped over a matrix of cylinders. The mesh layers increase the drag of the model canopy, while they also realistically simulate the strong damping of turbulent fluctuations inside the canopy. In addition to adding layers of mesh, the original 90 degree angle of the forest edge is tapered such that it more closely resembles the profile of the forest edge from a field experiment. The high vertical resolution of the wind-tunnel observations for the calibrated forest model shows both more detail and confirms previous findings from the field experiment. For example, in the region just above the canopy, where the slower wind flow inside the canopy mixes with the faster flow aloft, the streamwise skewness shows a strong zigzag pattern as a function of height and an increase in the streamwise velocity standard deviation.