# Effects of Turbulence Modeling on the Simulation of Wind Flow over Typical Complex Terrains
## 3 Computational Settings  
### Validation Cases  
The test cases in this paper are selected within different scales of the mountain ranging from the wind tunnel experiment to the field measurements, and are briefly described below.  
Case 1: 3D hill wind tunnel experiment.  
The wind tunnel experiment of the 3D hill was carried out by [PERSON] et al. [37; 38] in 1999, in which a neutrally stratified atmospheric boundary layer was simulated using different scale roughness blocks, and the test section floor was covered with plywood (surface roughness length, \(z_{0}\) = 0.01 mm). The wind speed (\(U_{\text{ref}}\)) outside of the boundary layer was maintained at 5.8 m/s. The model hill in the wind tunnel was machined from wood with a cross-section of \(z_{\text{s}}(x,y)=H\text{cos}^{2}(\pi(x^{2}+y^{2})^{1/2}/2L)\), \(H\) = 40 mm, and \(L\) = 100 mm. Figure 1 shows the details of the hill and coordinate system used in the study, where \(x,y\), and \(z\) are the streamwise, spanwise, and vertical directions, respectively.  
Case 2: Askervein hill field experiment.  
The Askervein hill project [39; 40], carried out in 1982 and 1983, is a major experimental study of the atmospheric boundary layer at a real atmospheric scale. About 50 anemometer towers (equipped with cup and sonic anemometers) were deployed in this experiment, 30 of which were used to observe the wind flow at a 10 m height, arranged on the A and AA (223\({}^{\circ}\)-43\({}^{\circ}\)) lines, and the B line (133\({}^{\circ}\)-313\({}^{\circ}\)) perpendicular to them (see Figure 2). In this paper, the case named \"TU-03B\", which has about three hours of wind measurement data, was selected to verify the numerical simulation results. The atmospheric stability in this case is close to neutral, the incoming flow direction (210\({}^{\circ}\), i.e., the \(x\)-axis direction shown in Figure 2) is approximately parallel to the A line, and the upstream of the hill is uniformly covered with sparse vegetation and is very flat (\(z_{0}\) = 0.027 m). The wind measurement data at the RS point are generally used as a reference for the inflow during the validation.  
Figure 1: Schematic of the geometrical configuration of the 3D hill model.  
Case 3 and Case 4: Bolund island field experiment.  
The Bolund island experiment was conducted for three months between 2007 and 2008 [41; 42]. There are about 35 anemometers, including 23 sonic and 12 cup anemometers, installed on 10 masts at heights between 2 and 15 m to measure the wind flow. These masts are arranged on lines A and B (see Figure 3). There are four masts along line A (along the \(x\)-axis), including M1, M2, M3, and M4, and along line B, which are M7, M6, M3, and M8. The experiment has four experimental conditions, two of which are chosen in this paper, with winds from the west (270\({}^{\circ}\), Case 3) and southwest (239\({}^{\circ}\), Case 4). The reference of the inlet wind speed and turbulent kinetic energy is obtained from M0, a mast without any disturbance. The roughness length on the island is 0.015 m, which is the same as that of the area filled with green lines (\(x>327\) m), and 0.0003 m over the water surface. The atmospheric stability during the experiments was neutral to slightly stable. The thermal and Coriolis effects are almost negligible due to the small height of the island.