Surface Roughness in Stratified Turbulent Ekman Flow

作者：Jonathan Kostelecky, Cedrick Ansorge · 发表于：Boundary-Layer Meteorology · 年份：2025 · DOI：10.1007/s10546-024-00895-5 · 被引用次数：2 · 研究领域：Fluid Dynamics and Turbulent Flows、Wind and Air Flow Studies、Meteorological Phenomena and Simulations

Abstract The interplay of surface roughness and stable stratification is investigated by direct numerical simulation of Ekman flow. Our setup is well within the turbulent regime, reaching a friction Reynolds number of $$Re_\tau \approx 2700$$ R e τ ≈ 2700 . Further, we reach the verge of the fully rough regime under neutral conditions with a non-dimensional obstacle height $$H^+\approx 40$$ H + ≈ 40 , corresponding to a z-nought parameter in viscous units $$z_0^+\approx 2$$ z 0 + ≈ 2 . Stability is imposed via a gradual decrease of surface buoyancy from neutral (no stratification) to very strong stratification. The reduced Reynolds number ( $$Re_\tau $$ R e τ ) in comparison to atmospheric problems warrants consideration of viscous effects on our results, and we demonstrate a correction method that consistently incorporates viscous effects, thus reducing the spread of data from our numerical results. The weakly stable regime is maintained at higher stability due to efficient production of turbulence kinetic energy which counteracts buoyant restoring forces in the presence of roughness. When scaled according to Monin–Obukhov similarity theory (MOST) our results for weak stability compares excellent to known formulations based on atmospheric observations. The coefficients of the stability correction functions for momentum and heat are estimated as $$\beta _\textrm{m}=3.45$$ β m = 3....