Practical aspects concerning the use of 3D Navier-Stokes solvers as prediction tools for micro-siting of wind energy installations are considered. Micro-siting is an important issue for a successful application of wind energy in sites of complex terrain. There is a constantly increasing interest in using mean wind flow predictions based on Reynolds averaged Navier-Stokes (RANS) solvers in order to minimize the number of required field measurements. In this connection, certain numerical aspects, such as the extent of the numerical flow domain, the choice of the appropriate inflow boundary conditions, and the grid resolution, can decisively affect the quality of the predictions. In the present paper, these aspects are analyzed with reference to the Askervein hill data base of full scale measurements. The objective of the work is to provide guidelines with respect to the definition of appropriate boundary conditions and the construction of an adequate and effective computational grid when a RANS solver is implemented. In particular, it is concluded that (a) the ground roughness affects the predictions significantly, (b) the computational domain should have an extent permitting the full development of the flow before entering the region of interest, and (c) the quality of the predictions at the local altitude maxima depends on the grid density in the main flow direction.

1.
Endlich
,
R. M.
,
Ludwig
,
F. L.
, and
Bhumralkar
,
C. M.
, 1982, “
A Diagnostic Model for Estimating at Potential Sites for Wind Turbines
,”
J. Appl. Meteorol.
0021-8952,
21
, pp.
1441
1454
.
2.
Tombrou
,
M.
,
Lalas
,
D. P.
,
Tryfonopoulos
,
D. A.
, and
Panourgias
,
J.
, 1993, “
Tests of Prediction Effectiveness of Wind Energy Computer Models in Complex Terrain
,”
Proceedings of ECWEC’93
,
Lubeck, Travenmude, Germany
, March 8–12, pp.
599
602
.
3.
Lalas
,
D. P.
,
Panagiotidis
,
T. C.
, and
Tryfonopoulos
,
D. A.
, 1994, “
A Hybrid Micrositing Model for Wind Flow Simulation over Complex Topographies
,”
Proceedings of ECWEC’94
,
Thessaloniki, Greece
, October 10–14, pp.
285
290
.
4.
Jackson
,
P. S.
, and
Hunt
,
J. C. R.
, 1975, “
Turbulent Wind Flow over a Low Hill of Moderate Slope
,”
Q. J. R. Meteorol. Soc.
0035-9009,
101
, pp.
929
955
.
5.
Mason
,
P. J.
, and
Sykes
,
R. I.
, 1979, “
Flow Over an Isolated Hill of Moderate Slope
,”
Q. J. R. Meteorol. Soc.
0035-9009,
105
, pp.
383
395
.
6.
Beljaars
,
A. C. M.
,
Walmsley
,
J. L.
, and
Taylor
,
P. A.
, 1987, “
A Mixed Spectral Finite-difference Model for Neutrally Stratified Boundary-Layer Flow over Roughness Changes and Topography
,”
Boundary-Layer Meteorol.
0006-8314,
38
, pp.
273
303
.
7.
Bergeles
,
C. G.
, 1985, “
Numerical Calculation of Turbulent Flow Around Two-Dimensional Hills
,”
J. Wind. Eng. Ind. Aerodyn.
0167-6105,
21
, pp.
307
321
.
8.
Tryfonopoulos
,
D. A.
,
Glekas
,
J. P.
, and
Bergeles
,
G. C.
, 1989, “
Reliability of Two Numerical Codes in Predicting the Wind Field in Complex Terrain
,”
Wind Eng.
0309-524X,
13
, pp.
324
337
.
9.
Glekas
,
J. P.
, and
Bergeles
,
C. G.
, 1993, “
A Numerical Method for Recirculating Flows on Generalized Coordinates: Application in Environmental Flows
,”
Appl. Math. Model.
0307-904X,
17
, pp.
506
521
.
10.
Apsley
,
D. D.
, and
Castro
,
I. P.
, 1997, “
Flow and Dispersion over Hills: Comparison between Numerical Predictions and Experimental Data
,”
J. Wind. Eng. Ind. Aerodyn.
0167-6105,
67/68
, pp.
375
386
.
11.
Kim
,
H. G.
,
Lee
,
C. M.
,
Lim
,
H. C.
, and
Kyong
,
H. C.
, 1997, “
An Experimental and Numerical Study on the Flow over Two-Dimensional Hills
,”
J. Wind. Eng. Ind. Aerodyn.
0167-6105,
6
, pp.
17
33
.
12.
van Doormaal
,
J. P.
, and
Raithby
,
G. D.
, 1984, “
Enhancement of SIMPLE method for predicting incompressible fluid flows
,”
Numer. Heat Transfer
0149-5720,
7
, pp.
147
163
.
13.
Kim
,
H. G.
, and
Patel
,
V. C.
, 2000, “
Test of Turbulence Models for Wind Flow on Terrain with Separation and Recirculation
,”
Boundary-Layer Meteorol.
0006-8314,
94
, pp.
5
21
.
14.
Wilson
,
K. G.
, and
Kogut
,
J.
, 1974, “
The Renormalization Group and the ε Expansion
,”
Phys. Rep.
0370-1573,
12
, pp.
75
199
.
15.
Kim
,
H. J.
,
Patel
,
V. C.
, and
Lee
,
C. M.
, 2000, “
Numerical Simulation of Wind Flow over Hilly Terrain
,”
J. Wind. Eng. Ind. Aerodyn.
0167-6105,
87
, pp.
45
60
.
16.
Bergeles
,
G.
,
Glekas
,
I.
,
Prospathopoulos
,
I.
, and
Voutsinas
,
S. G.
, 1996, “
Statistical and Physical Modelling of Wind Resources in Complex Terrain: Assessment of the Applicability of a 3D Navier Stokes Code
,”
Proceedings of EUWEC’96
,
Goteborg, Sweden
.
17.
Theodorakakos
,
A.
, and
Bergeles
,
G.
, 2001, “
A Telescopic Local Refinement Technique for Wind Flow Simulation over Complex Terrain
,”
Wind Eng.
0309-524X,
4
, pp.
77
98
.
18.
Mickle
,
E.
,
Cook
,
N. J.
,
Hoff
,
A. M.
,
Jensen
,
N. O.
,
Salmon
,
J. R.
,
Taylor
,
P. A.
,
Tetzlaff
,
G.
, and
Teunissen
,
H. W.
, 1988, “
The Askervein Hill Project: Vertical Profiles of Wind and Turbulence
,”
Boundary-Layer Meteorol.
0006-8314,
14
, pp.
235
246
.
19.
Walmsley
,
J. L.
, and
Taylor
,
P. A.
, 1996, “
Boundary-Layer Flow Over Topography: Impacts on the Askervein Study
,”
Boundary-Layer Meteorol.
0006-8314,
78
, pp.
291
320
.
20.
Maurizi
,
A.
, 2000, “
Numerical Simulation of Turbulent Flows over 2-D Valleys using Three Versions of the k-ε Closure Model
,”
J. Wind. Eng. Ind. Aerodyn.
0167-6105,
85
, pp.
59
73
.
21.
Kim
,
H. J.
,
Patel
,
V. C.
, and
Lee
,
C. M.
, 2000, “
Numerical Simulation of Wind Flow over Hilly Terrain
,”
J. Wind. Eng. Ind. Aerodyn.
0167-6105,
87
, pp.
45
60
.
22.
Wilcox
,
D. C.
, 1993,
Turbulence Modeling for CFD
,
DCW Industries, Inc.
, La Cañada, CA.
23.
Rodi
,
W.
, 1980,
Turbulence Models and Their Application in Hydraulics—A State of the Art Review
, Institut fur Hydromechanik, University of Karlshrue, Germany.
24.
Schlichting
,
H.
, 1968,
Boundary-Layer Theory
,
McGraw-Hill
,
New York
.
25.
Panofsky
,
H. A.
, and
Dutton
,
J. A.
, 1984,
Atmospheric Turbulence Models and Methods for Engineering Applications
,
Wiley
,
New York
.
26.
Launder
,
B. E.
, and
Spalding
,
D. B.
, 1974, “
The Numerical Computation of Turbulent Flows
,”
Comput. Methods Appl. Mech. Eng.
0045-7825,
3
, pp.
269
289
.
27.
Duynkerke
,
P. G.
, 1988, “
Application of the E-ε Turbulence Closure Model to the Neutral and Stable Atmospheric Boundary Layer
,”
J. Atmos. Sci.
0022-4928,
45
, pp.
865
880
.
28.
Patankar
,
S. V.
, and
Spalding
,
D. B.
, 1970,
Heat and Mass Transfer in Boundary Layers
,
2nd ed.
,
Intertext Books
,
London
.
29.
Wilcox
,
D. C.
, 1993, “
Sound Field Computations in a Stratified Moving Medium
,”
J. Acoust. Soc. Am.
0001-4966,
94
(
2
), pp.
1080
1095
.
30.
Hanna
,
S. R.
,
Briggs
,
G. A.
, and
Hosker
,
R. P.
, 1982,
Handbook in Atmospheric Diffusion
, Technical Information Center, U.S. Department of Energy, U.S.A.
31.
Zbigniew
,
S.
, 1989,
Structure of the Atmospheric Boundary Layer
,
Prentice Hall
,
Englewood Cliffs, NJ
.
32.
Wyngard
,
J. C.
, 1975, “
Modeling the Planetary Boundary Layer. Extension to the Stable Case
,”
Boundary-Layer Meteorol.
0006-8314,
9
, pp.
441
460
.
33.
Taylor
,
P. A.
, and
Teunissen
,
H. W.
, 1983, “
ASKERVEIN’82: Report on the September/October 1982 Experiment to Study Boundary-Layer Flow over Askervein
,” Internal Report of Atmospheric Environment Service, Downsview, Ontario, Canada.
34.
Raithby
,
G. D.
,
Stubley
,
G. D.
, and
Taylor
,
P. A.
, 1987, “
Askervein Hill Project: A Finite Control Volume Prediction of Three-Dimensional Flows Over the Hill
,”
Boundary-Layer Meteorol.
0006-8314,
39
, pp.
247
267
.
35.
Castro
,
F. A.
,
Palma
,
J. M. L. M.
, and
Silva Lopes
,
A.
, 2003, “
Simulation of the Askervein Flow. Part 1: Reynolds Averaged Navier-Stokes Equations (k-ε Turbulence Model)
,”
Boundary-Layer Meteorol.
0006-8314,
107
(
3
), pp.
501
530
.
You do not currently have access to this content.