Wall-modelled large-eddy simulations of the neutral atmospheric boundary layer over rough homogeneous and heterogeneous surfaces

We present a high-Reynolds-number large-eddy simulations (LES) study of the neutral atmospheric boundary layer (ABL) over both homogeneous and heterogeneous rough-wall surfaces. The LES utilise a coupling of the stretched vortex (SV) subgrid-scale (SGS) model with a new wall model based on the implementation of a wall-stress-like (WS) boundary condition at the wall-adjacent cell combined with an ordinary differential equation model of the wall shear stress (WSODE). The WSODE model is derived from the virtual-wall model but eliminates both the virtual wall itself and some model parameters. For the ABL over homogeneous roughness, the SV-WSODE model successfully captures the streamwise wall shear stress, the logarithmic velocity profile, and the turbulence energy spectra, demonstrating performance comparable to the widely adopted Lagrangian-averaged scale-dependent SGS model combined with the simple log-law wall model. Given that the WSODE model originates from the streamwise momentum equation and inherently preserves non-equilibrium effects in its formulation, the SV-WSODE model is potentially applicable to ABL flow over any rough heterogeneous surfaces. The simulation results exhibit favourable agreement with two well-known datasets – one from field observations, and the other from laboratory experimental measurements – supporting the capability of the SV-WSODE framework for the prediction of diverse rough-surface ABL flows.