A first-order closure for disturbed plant-canopy flows, and its application to winds in a canopy on a ridge

To calculate disturbed wind flows in plant canopies, we studied a variant of the K proportional to lambda k(1/2) first-order closure (where K is the eddy viscosity, k is the turbulent kinetic energy calculated from its simplified governing differential equation, and lambda is an algebraic length-scale). We compare numerical solutions using this closure (which admits only three empirical constants) with earlier observations of mean wind, shear stress, and turbulent kinetic energy in three, quite different, uniform canopy flows, and in disturbed canopy flow over a ridge. The closure performs as well as or better than the solutions of others based on modifications of the 'k-epsilon' closure, where epsilon is the rate of dissipation of k.