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 vari ant 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 clo sure (which admits only three empirical constants) with earlier observ ations of mean wind, shear stress, and turbulent kinetic energy in thr ee, quite different, uniform canopy flows, and in disturbed canopy flo w over a ridge. The closure performs as well as or better than the sol utions of others based on modifications of the 'k-epsilon' closure, wh ere epsilon is the rate of dissipation of k.