A Field Study of the Mean Pressure About a Windbreak

Abstract

To provide additional field data for assessingwindbreak flow models, mean ground-level pressurehas been measured upstream and downstream from along porous fence (height H = 1.25 m, resistancecoefficient kr = 2.4). Measurements were madeduring periods of near-neutral stability and near-normallyincident flow, with the fence standing on bare soil(roughness length, z0 ≈ 0.8 cm;H/z0 ≈ 160), or within a plant canopy. The mean pressure field,measured far from the ends of the fence, was foundto be quite insensitive to mean wind direction(\(\bar \alpha\), zero for perpendicular flow), for|\(\bar \alpha\)| less than about 25°.