Stratified flow over non-uniform surface conditions: Mixing-length model

The response of a neutrally stratified atmospheric surface layer to sudden changes in surface roughness and temperature is investigated by solving the steady-state boundary-layer equations. Near the discontinuities, the distributions of velocity and shear stress are found to be critically dependent upon whether or not the pressure and buoyancy terms are retained in the governing equations. Computed distributions of velocity and shear stress are found to be in good agreement with windtunnel and field data. The growth of the internal boundary layer under neutral conditions for smooth to rough transitions follows the 0.8 power law; however, rough to smooth transitions are associated with a 0.7 power law.