# Correction of Field-Measured Wind Speed Affected by Deterministic Interference Factors
## 3 Wind Speed Revise
### NLDI Site
#### 3.1.2 Numerical Simulation Verification  
ANSYS 16.0 was used in the numerical simulation of NLDI, which combined ICEM and Fluent software for pretreatment and calculation, respectively. The whole process followed these steps: (1) modeling of the actual terrain, (2) setting of computational domain, (3) division of computational grid, (4) definition of boundary conditions. Modeling the surface with the traditional triangular mesh is relatively complicated due to the continuous fluctuation of the actual terrain. Therefore, the RhinoResurf plug-in based on Non-Uniform Rational B-Spline (NURBS) was used for landform surface reconstruction to improve the efficiency and accuracy. The Digital Elevation Model (DEM) data of NLDI were derived from Google Earth and transformed into a contour plot in CAD format; the contour lines should be continuous, closed, and disjointed. Then, the command item \"create single NURBS surface from curve group\" in the plug-in was selected to obtain the best fitting surface by adjusting the control parameters. Considering different wind incident directions, the computational domain was set as an interior cylinder and an exterior cuboid; hence, wind directions were changed by rotating the interior domain. The distance from the inlet, outlet, and side wall of the computational domain to the island's edges should be sufficiently long to fully develop the turbulence in the 3D flow field [20, 21] ([PERSON] and [PERSON]. 2011; [PERSON] and [PERSON]. 2019). The maximum altitude of the island marked as H was 0.3 km; thus, the dimensions of the exterior domain were 25 \(\times\) 8.2 \(\times\) 2.1 km\({}^{3}\) (length \(\times\) width \(\times\) height). The inlet, side walls, and outlet were set to 2.1, 2.8, and 20 km away from the corresponding island's edge separately (Figure 5). Figure 4: WTT model of Noi Ling Ding Island: (**a**) with NLDI; (**b**) without NLDI. Hybrid grids were adopted in the mesh division, unstructured grids were used in the interior domain, and structured grids were used in the exterior domain. The interface operation was applied to connect these meshes. The near-wall grids should be refined, and the grid height y\({}^{+}\) of the first layer should be less than 5, owing to the enormous velocity gradient over the mountain surface. After several adjustments, the final mesh scheme was determined as follows: for unstructured grids in the inner domain, the grid height was 0.5 m in the first layer on the mountain surface, the maximum grid size was 20 m, the grid stretching ratio was 1.1, and the number of grid layers in the boundary layer was 15. For structural grids in the exterior domain, the minimum grid size in the horizontal direction was 50 m, and the maximal grid size was 200 m with a stretching ratio of 1.2. In the vertical direction, the size of the near-wall grid was 0.5 m, and the top grid size was 50 m with a stretching ratio of 1.1. The total number of grids in the computational domain was nearly 6 million. The shear-stress transport \(k\)-\(\omega\) (SST \(k\)-\(\omega\)) model was selected as the turbulence model for simulations [21; 22]. The model has good performance for the bounded wall and low Reynolds number flows, especially for the flow around. The boundary conditions were determined as follows: the vertical profile of the mean wind was used as the inlet boundary condition, and zero static pressure was applied at the outlet plane. The ground boundary is modeled as a rough wall with the roughness height of 0.00125 m and roughness constant of 0.75. The upper face and the lateral sides of the computational domain is modeled with symmetry boundary conditions. According to [PERSON] et al.