First- and Second-Order Closure Models for Wind in a Plant Canopy

Abstract Katul and Chang recently compared the performance of two second-order closure models with observations of wind and turbulence in the Duke Forest canopy, noting that such models “alleviate some of the theoretical objections to first-order closure.” This paper demonstrates that, notwithstanding those (valid) theoretical objections, Duke Forest wind simulations of comparable quality can be obtained using a first-order closure, namely, eddy viscosity K ∝ λk, where k is the turbulent kinetic energy and λ is a turbulence length scale. It is concluded that, most often, uncertainty in the drag coefficient will limit the accuracy of modeled wind statistics, regardless of the turbulence closure chosen.