wind energy resource evaluation in a site of central italy ... - WindSim

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considered as a virtual wall with no friction, describing a wind tunnel containing allthe air flowing away, while the flow reaches the maximum velocity value (freestream velocity) at the top of the boundary, as shown in the previous figure 2.1.2.2 Geometrical model and inlet BCThe model analyzed forward is a simple flat terrain 6000 meters long and 100meters large, a height above the terrain set at 800 meters. The height of the ABLwas fixed at 500 m and a geostrophic wind of 10 m/s was set above 500 m up to 800m.Different cases of terrain roughness have been studied and for each case the correctinlet velocity profile was chosen. The model used for the inlet profile was the loglaw, explained in chapter 1, while the turbulence profile was set by means of theparticular equations also reported in the introductive chapter.For the purpose of data reduction the vertical profiles of the wind speed have beenextracted in 4 different stations along the flat terrain, respectively station 1 at the17
inlet position (0 meters), station 2 at 2000 meters, station 3 at 4000 meters andstation 4 at the outlet position (6000 meters).2.3 Vertical discretization sensitivityTo determine the influence on the results of the vertical discretization a series ofsimulations has been run. These simulations have been done keeping constant theroughness value and varying the vertical number of cells, without any change of theheight distribution factor (HDF). According to this, the first group of simulations havebeen done for roughness R=0.01 with 20, 40 and 60 vertical number of cells. Theheight distribution factor has been set at the value 0.1. Concerning the second groupof simulations, the roughness value has been set to R=0.6 and the number of verticalcells was the same of the previous group.Figure 2.2: Vertical position in different stations for R=0.01 and HDF=0.1.Figure 2.2 shows the overlapping of the vertical profiles relative to station 1 (inlet ofthe geometrical model) and those of station 2. As It can be seen there is no shiftbetween the three curves and then the simulation with the lowest number ofvertical cells is enough accurate to describe the vertical profile. The same result canbe deduced from the right side of the figure where the wind profiles at the differentstations were plotted in log scale.18
Page 1 and 2: UNIVERSITÀ DEGLI STUDI DI CAGLIARI
Page 3 and 4: IndexIndex page IAcknowledgmentsVII
Page 5 and 6: CHAPTER 4: Characteristics of the s
Page 7 and 8: 6.7.1 Mean wind velocity page 1096.
Page 9 and 10: This thesis is the result of a prac
Page 11 and 12: WindSim is a software developed by
Page 13 and 14: CHAPTER 1. Atmospheric Boundary Lay
Page 15 and 16: Figure 1.1: Example of an atmospher
Page 17 and 18: 1.5 The WindSim numerical codeWindS
Page 19 and 20: (κ−ε RNG or the Low Reynolds),
Page 21 and 22: 1.5.4 RESULTSThe Results module all
Page 23 and 24: Figure 1.2: Example of TKE vertical
Page 25: CHAPTER 2. Simulations over flat te
Page 29 and 30: 2.4 Height distribution factor sens
Page 31 and 32: e decreased, to avoid to build thin
Page 33 and 34: Figure 2.10: Vertical profiles for
Page 35 and 36: CHAPTER 3. Simulations over 2D hill
Page 37 and 38: Table 3.1: Measurement coordinatesS
Page 39 and 40: The results shown above demonstrate
Page 41 and 42: Figure 3.6: Sketch of the 15 km lon
Page 43 and 44: Figure 3.9: Influence of the height
Page 45 and 46: Figure 3.13: Zoom of the hill top r
Page 47 and 48: 3.5.2) = ∙.The two models for att
Page 49 and 50: H [m] hill heightν[m 2 /s] air cin
Page 51 and 52: Figure 3.18: Particular of the nume
Page 53 and 54: Finally, the horizontal x velocity
Page 55 and 56: Figure 3.25: Z velocity componentFi
Page 57 and 58: 3.6 RemarksA CFD study of a boundar
Page 59 and 60: Some experimental wind data of this
Page 61 and 62: Both the pictures 4.3 and 4.4 have
Page 63 and 64: Table 4.2: Description of the color
Page 65 and 66: In this periods, data are recorded
Page 67 and 68: In the following pages, a short des
Page 69 and 70: 4.3.2 Mast 5424-15 m Period April-M
Page 71 and 72: 4.3.4 Mast 5424-15 m Period Novembe
Page 73 and 74: 4.3.6 Mast 5428-40 m Period April-M
Page 75 and 76: 4.3.8 Mast 5428-50 m Period Novembe
Page 77 and 78:
4.3.10 Mast 5428-30 m Period Novemb
Page 79 and 80:
4.4.2 Mast 542870
Page 81 and 82:
4.5.2 Mast 542872
Page 83 and 84:
CHAPTER 5. Test of the Free Stream
Page 85 and 86:
case the wind is blowing from the e
Page 87 and 88:
Geometrical modelTable 5.3: Input p
Page 89 and 90:
Figure 5.6: Vertical profiles in po
Page 91 and 92:
The orthogonalization of the grid h
Page 93 and 94:
Figure 5.9: Map of speed-ups for di
Page 95 and 96:
Figure 5.30: Speed-2D at 30 m heigh
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Figure 5.12: Speed-2D at 30 m heigh
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CHAPTER 6. Analysis of the wind fie
Page 101 and 102:
Table 6.2: Boundary conditions and
Page 103 and 104:
6.5 Vertical profiles of VelocityTo
Page 105 and 106:
characterized by high wind speed (5
Page 107 and 108:
From the error analysis, it is foun
Page 109 and 110:
Anyhow, the trend of the linear int
Page 111 and 112:
Concerning the CFD simulations, val
Page 113 and 114:
Analyzing RMS error table for tower
Page 115 and 116:
A general overview of the figure 6.
Page 117 and 118:
6.7 Cross Checking of wind dataIn t
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Figure 6.8 a/bFigure 6.8 c/dFigure
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Table 6.11: RMS error for cross che
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Figure 6.9 e/fFigure 6.9 g/hFigure
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Figure 6.10 g/hFigure 6.10 i/lFigur
Page 127 and 128:
to have a better agreement during t
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Figure 7.2: Weibull fitting of the
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Figure 7.5: Perspective view of the
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The calculated AEP has been reporte
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ConclusionsIn this thesis the evalu
Page 137 and 138:
Bibliography[1] CRASTO G. - Numeric
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