Publishers version - DTU Orbit

Kaimal spectra we get
Γ = 3.9
L = 0.59z (81)
αε 2/3 = 3.2 u2 ∗
z 2/3,
where the dependence on z is a consequence of surface layer scaling. For the Simiu & Scanlan
spectra, where the fit is shown in Figure 38, we get
Γ = 3.8
αε 2/3 = 2.8 u2 ∗
z 2/3
and for both models u∗ can be obtained from Figure 36.
L [m]
200
100
Γ
50
30
20
10
5
4
3
2
1
10
L = 0.79z (82)
15 20
300
180
120
80
U [m/s]
0.01 0.1 1 10
25
30
αε 2/3 [m 4/3 s −2 ]
40
40
z [m]
100 200 300
z [m]
10 m/s
25
50
15
60
10
U
30
25
20
15
70
60
70 80
50
40
Figure 40: The parameters of the spectral tensor model derived from fits to the ESDU model
spectra for turbulence over the sea. Given U and z, all three parameters can be extracted
from these plots.
It is more complicatedto getthe parameters from the ESDU modelsbecause the spectra no
longer depend on U and z in a simple way. For each set {U,z}, a fit to the tensor model has
66 DTU Wind Energy-E-Report-0029(EN)
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