Numerical Study of the Neutral Atmospheric Boundary Layer Over Complex Terrain

Abstract

We evaluate the Reynolds-averaged Navier-Stokes equations available as commercial computational fluid dynamics code for the simulation of a neutral atmospheric boundary layer and attempt to define a proper numerical simulation procedure. Four turbulence models, including two-equation and Reynolds stress models, were evaluated together with two near-wall models. Mesh and map digitization sensitivity tests were also performed. The simulations were compared to experimental field data from the Askervein Hill in Scotland. The results show that the simulations performed with ANSYS CFX 12.1 on a proper mesh and topological map with a Reynolds stress turbulence model provided the best wind-speed predictions when compared to the experimental results.

On Turbulent Fluxes During Strong Winter Bora Wind Events

“…For instance, the Bolund experiment Berg et al 2011;Diebold et al 2013) took place over an eliptically shaped peninsula, surrounded by sea from nearly all sides, resulting in an extended upwind homogeneous fetch. Another example is the Askervein Hill, an eliptical hill surrounded by low and uniform vegetation, again resulting in fetches that are highly homogeneous and ideal for numerical modelling (Undheim et al 2006;Lopes et al 2007;Moreira et al 2012). Most recently, Grant et al (2015) investigated airflow observations at Leac Gharbh, a forested ridge located off the Scottish mainland.…”

Separation of upslope flow over a uniform slope

“…In predictive models, flow separation over slopes is sensitive to the details of the turbulent models employed (Mason 1987;Moreira et al 2012), and hence an understanding of the underlying processes is vital for developing turbulence closure for numerical models. While a substantial number of theoretical, numerical and laboratory studies have been conducted on flow over mountains under stable and neutral conditions (Taylor & Teunissen 1987;Baines 1995;Raupach & Finnigan 1997;Belcher & Hunt 1998), there are few fundamental studies on flow separation under convective conditions.…”

CFD simulation of wind flow over natural complex terrain: Case study with validation by field measurements for Ria de Ferrol, Galicia, Spain

“…In fact, the CFD simulations did predict the flow separation in the lee of the hill, albeit with some discrepancies. Later 3D steady RANS simulations for the Askervein hill were made by -among others - Kim et al (2000), Prospathopoulos and Voutsinas (2006), Undheim et al (2006), Balogh et al (2012) and Moreira et al (2012), while both steady and unsteady RANS simulations were made by Castro et al (2003), hybrid RANS/LES by Bechmann and Sorensen (2010) and LES simulations by Silva Lopes et al (2007).…”