Appropriate boundary conditions for computational wind engineering models using the k-ε turbulence model

Richards, P.J.; Hoxey, R.P.

doi:10.1016/b978-0-444-81688-7.50018-8

Cited by 129 publications

(149 citation statements)

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“…In neutral conditions, a relationship amongst k-ε coefficients is prescribed to obtain consistency with wellestablished log profiles in surface-layer neutral conditions (Richards and Hoxey, 1993):…”

Section: Modelsmentioning

confidence: 99%

A methodology for the design and testing of atmospheric boundary layer models for wind energy applications

2017

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Abstract. The GEWEX Atmospheric Boundary Layer Studies (GABLS) 1, 2 and 3 are used to develop a methodology for the design and testing of Reynolds-averaged Navier-Stokes (RANS) atmospheric boundary layer (ABL) models for wind energy applications. The first two GABLS cases are based on idealized boundary conditions and are suitable for verification purposes by comparing with results from higher-fidelity models based on large-eddy simulation. Results from three single-column RANS models, of 1st, 1.5th and 2nd turbulence closure order, show high consistency in predicting the mean flow. The third GABLS case is suitable for the study of these ABL models under realistic forcing such that validation versus observations from the Cabauw meteorological tower are possible. The case consists on a diurnal cycle that leads to a nocturnal low-level jet and addresses fundamental questions related to the definition of the large-scale forcing, the interaction of the ABL with the surface and the evaluation of model results with observations. The simulations are evaluated in terms of surface-layer fluxes and wind energy quantities of interest: rotor equivalent wind speed, hub-height wind direction, wind speed shear and wind direction veer. The characterization of mesoscale forcing is based on spatially and temporally averaged momentum budget terms from Weather Research and Forecasting (WRF) simulations. These mesoscale tendencies are used to drive single-column models, which were verified previously in the first two GABLS cases, to first demonstrate that they can produce similar wind profile characteristics to the WRF simulations even though the physics are more simplified. The added value of incorporating different forcing mechanisms into microscale models is quantified by systematically removing forcing terms in the momentum and heat equations. This mesoscale-to-microscale modeling approach is affected, to a large extent, by the input uncertainties of the mesoscale tendencies. Deviations from the profile observations are reduced by introducing observational nudging based on measurements that are typically available from wind energy campaigns. This allows the discussion of the added value of using remote sensing instruments versus tower measurements in the assessment of wind profiles for tall wind turbines reaching heights of 200 m.Published by Copernicus Publications on behalf of the European Academy of Wind Energy e.V. 36 J. Sanz Rodrigo et al.: A methodology for the design and testing of atmospheric boundary layer models

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Section: Modelsmentioning

confidence: 99%

A methodology for the design and testing of atmospheric boundary layer models for wind energy applications

2017

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“…The first cause of discrepancy lies in the inconsistency between the fully-developed ABL inlet profiles and the rough-wall function formulation (Riddle et al 2004;Franke et al 2004Franke et al , 2007Blocken et al 2007a,b;Hargreaves and Wright 2007). Furthermore, the inlet profile for the turbulence kinetic energy, k, proposed by Richards and Hoxey (1993), assumes a constant value with height, in conflict with wind-tunnel measurements (Leitl 1998;Xie et al 2004;Yang et al 2009), where a variation of k with height is observed.…”

Section: Introductionmentioning

confidence: 77%

“…Assuming a steady, incompressible and horizontally homogenous flow, a two-dimensional ABL can be described by the following equations for momentum, turbulent kinetic energy, k, and turbulent dissipation rate, ε (Richards and Hoxey 1993):…”

Section: Theorymentioning

confidence: 99%

“…rough or smooth, depending on the boundary surface properties. Interestingly, the rough-wall treatment is not based on the sand-grain equivalent roughness parameters but depends directly on the aerodynamic roughness, as prescribed by Richards and Hoxey (1993).…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the upstream turbulent characteristics of a homogeneous ABL flow are often modelled using the profiles suggested by Richards and Hoxey (1993) for mean velocity, turbulent kinetic energy and turbulent dissipation rate.…”

Section: Introductionmentioning

confidence: 99%

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A Comprehensive Modelling Approach for the Neutral Atmospheric Boundary Layer: Consistent Inflow Conditions, Wall Function and Turbulence Model

Parente

Gorlé

Beeck

et al. 2011

Boundary-Layer Meteorol

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We report on a novel approach for the Reynolds-averaged Navier-Stokes (RANS) modelling of the neutral atmospheric boundary layer (ABL), using the standard k-ε turbulence model. A new inlet condition for turbulent kinetic energy is analytically derived from the solution of the k-ε model transport equations, resulting in a consistent set of fully developed inlet conditions for the neutral ABL. A modification of the standard k-ε model is also employed to ensure consistency between the inlet conditions and the turbulence model. In particular, the turbulence model constant C μ is generalized as a location-dependent parameter, and a source term is introduced in the transport equation for the turbulent dissipation rate. The application of the proposed methodology to cases involving obstacles in the flow is made possible through the implementation of an algorithm, which automatically switches the turbulence model formulation when going from the region where the ABL is undisturbed to the region directly affected by the building. Finally, the model is completed with a slightly modified version of the Richards and Hoxey rough-wall boundary condition. The methodology is implemented and tested in the commercial code Ansys Fluent 12.1. Results are presented for a neutral boundary layer over flat terrain and for the flow around a single building immersed in an ABL.A. Parente

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Topographic change and numerically modelled near surface wind flow in a bowl blowout

Smyth

Hesp

Walker

et al. 2019

Earth Surf Processes Landf

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A number of studies have measured and numerically modelled near surface wind velocity over a range of aeolian landforms and made suppositions about topographic change and landform evolution. However, the precise measurement and correlation of flow dynamics and resulting topographic change have not yet been fully realized. Here, using repeated high‐resolution terrestrial laser scanning and numerical flow modelling within a bowl blowout, we statistically analyse the relationship between wind speed, vertical wind velocity, turbulent kinetic energy and topographic change over a 33‐day period. Topographic results showed that erosion and deposition occurred in distinct regions within the blowout. Deposition occurred in the upwind third of the deflation basin, where wind flow became separated and velocity and turbulent kinetic energy decreased, and erosion occurred in the downwind third of the deflation basin, where wind flow reattached and aligned with incident wind direction. Statistical analysis of wind flow and topographic change indicated that wind speed had a strong correlation with overall topographic change and that vertical wind velocity (including both positive and negative) displayed a strong correlation with negative topographic change (erosion). Only weak or very weak correlations exist for wind flow parameters and positive topographic change (accretion). This study demonstrates that wind flow modelling using average incident wind conditions can be utilized successfully to identify regions of overall change and erosion for a complex aeolian landform, but not to identify and predict regions where solely accretion will occur. © 2019 John Wiley & Sons, Ltd.

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Appropriate boundary conditions for computational wind engineering models using the k-ε turbulence model

Cited by 129 publications

References 5 publications

A methodology for the design and testing of atmospheric boundary layer models for wind energy applications

A methodology for the design and testing of atmospheric boundary layer models for wind energy applications

A Comprehensive Modelling Approach for the Neutral Atmospheric Boundary Layer: Consistent Inflow Conditions, Wall Function and Turbulence Model

Topographic change and numerically modelled near surface wind flow in a bowl blowout

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