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

H [m] hill heightν[m 2 /s] air cinematic viscosityThe numerical grid is built, in both S3H4 and S5H4 cases, with a non-orthogonal gridas shown in the further paragraphs.3.5.3 Case S3H4The case S3H4 has been studied in a geometrical model extending from streamwisecoordinates -1,5 m to 1,5 m, for a total length of 3 m. The width is 0,1 m while thetotal height is 2 m; thus, the blockage factor is 2%.The grid contains 130 cells in x-directions, 3 cells in y-direction and 60 cells invertical direction; the horizontal resolution has been increased in the hill profile, inorder to describe in a sufficient accurate way the behavior of the flow in the criticalzone. The height of the first cell is 2 mm, while the roughness height imposed in thewall function formula is 0,05 mm. Then, the condition stating that the first cellheight must be at least double of the roughness value is satisfied [1].The following figure 3.16 shows a particular of the numerical grid.Figure 1.16: Particular of the non-orthogonal regular grid for case S3H4.The boundary condition imposed on the top of the model is “wall with no-friction”,while at the bottom the terrain contains the roughness information all over thesurface.40