Pressure-gradient forcing methods for large-eddy simulations of flows in the lower atmospheric boundary layer

Simulated winds result from the balance between a simplified pressure gradient forcing (e.g., a constant pressure-gradient or a canonical Ekman balance) and the dissipation of momentum, due to vegetation drag. Little attention has been paid to the impacts of these forcing methods on flow features, despite practical challenges and unrealistic features, such as establishing stationary velocity or streak locking.

This study presents a technique for capturing the effects of a pressure-gradient force (PGF), associated with atmospheric patterns much larger than the computational domain for idealized simulations of near-surface phenomena. Four variants of this new PGF are compared to existing forcings, for turbulence statistics, spectra, and temporal averages of flow fields. Results demonstrate that most features of the turbulent flow are captured.