  In large eddy simulation of atmospheric boundary layer flows over wind farms,
wall-layer models are generally imposed for the surface fluxes without
considering the spatial variability of the surface roughness. In this study, we
consider the near-surface model in conjunction with square of the velocity
gradient tensor to model the adaptive dissipation of turbulence production. The
surface roughness is incorporated through Monin-Obhukhov similarity theory for
the computational cells immediately adjacent to the Earth's surface. The
underlying proposed near-surface model captures the significant amount of
Reynolds stresses in the near-surface and is able to maintain the log-law
profile in wind farms. The present study indicates that the suggested
`near-surface model' is relatively robust in comparison to the classical
`near-wall model'.
