The Bolund Experiment, Part II: Blind Comparison of Microscale Flow Models

Abstract

Bolund measurements were used for a blind comparison of microscale flow models. Fifty-seven models ranging from numerical to physical were used, including large-eddy simulation (LES) models, Reynolds-averaged Navier-Stokes (RANS) models, and linearized models, in addition to wind-tunnel and water-channel experiments. Many assumptions of linearized models were violated when simulating the flow around Bolund. As expected, these models showed large errors. Expectations were higher for LES models. However, of the submitted LES results, all had difficulties in applying the specified boundary conditions and all had large speed-up errors. In contrast, the physical models both managed to apply undisturbed 'free wind' boundary conditions and achieve good speed-up results. The most successful models were RANS with two-equation closures. These models gave the lowest errors with respect to speed-up and turbulent kinetic energy (TKE) prediction.

Variations of the Wake Height over the Bolund Escarpment Measured by a Scanning Lidar

“…The two-month long intensive measurement campaign produced a unique dataset of sonic and cup anemometer measurements at various heights for selected locations on the Bolund peninsula. Vertical lidar wind profiles complement the dataset (Bechmann et al 2009Berg et al 2011). Today the dataset of the Bolund experiment serves as a baseline reference for various studies with respect to numerical and physical modelling.…”

Network planning case study utilising real-time thermal ratings and computational fluid dynamics

“…The air temperature was set at 300k and a logarithmic boundary profile used, as suggested in [6]. This methodology had previously been validated by the authors using the Bolund Hill Experiment [7] The CFD results are used to generate a grid of normalised wind speeds across the area of interest. This is done by taking a surface of points 10m above the terrain and applying equation 1.…”

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

“…Field measurements of wind speed were performed during a 3-month period in 2007 and 2008 (Bechmann et al 2009. Bechmann et al (2011) report a blind comparison test of microscale flow models focused on reproducing the wind flow over the Bolund hill. 57 results were submitted from all branches of the wind energy industry.…”