CFD simulations to determine wind forces acting on plants

Abstract

Wind forces acting on plants can be calculated in CFD simulations using porous body elements. The simulations in this study showed close agreement with wind tunnel tests. Drag coefficients derived from wind-tunnel measurements can be used as input parameters for CFD simulations to estimate the drag forces on plants in wind flows. Two approaches for determining the porosity coefficient are presented and compared; both yield comparable results. Discrepancies occur primarily at low wind speeds in the range of 0-10 m/s, with deviations of up to 50%, due to the small absolute forces involved. However, this range is not relevant for the present work, which focuses on extreme wind speeds to better understand the loading of wire ropes as part of the supporting structure for climbing plants. Leaf shedding at high wind speeds is not represented in the simulation model, leading to an overestimation of wind forces in this range. To obtain conservative wind force values, a statistical adjustment of the drag coefficient is required, which reduces the remaining uncertainties. Once these adjustments are applied, the model can be used to estimate wind-induced drag forces on plants via CFD, reducing the number of physical models required.