# Computational Fluid Dynamics-Aided Simulation of Twisted Wind Flows in Boundary Layer Wind Tunnel
## 6 Concluding Remarks  
This paper has presented a procedural framework to achieve the optimal experimental setup for the generation of TWF in a wind tunnel based on CFD simulation results. Following the proposed procedures, the optimal configuration of the passive devices, especially the design of the guide vane system, to generate the desired TWF can be efficiently obtained by CFD simulation results in a numerical wind tunnel, enabling informed decisions for the final experimental setup in the actual wind tunnel. Several concluding remarks are drawn as follows:  
1. The numerical wind tunnel established using the RANS and LES techniques can serve as an effective tool to examine the rationality of the experimental setup. The RNG \(k\)-\(\varepsilon\) model for RANS delivered the best predictions of wind speed in a numerical wind tunnel, according to the comparison with the results from the actual wind tunnel. The LES model, the more computationally efficient approach, was also able to numerically simulate the wind field with satisfying accuracy. 2. Based on the numerical simulation results, the mechanism of a guide vane system in a TWF simulation has been discussed in detail. Three parameters governing the positions of the vanes have been emphasized in this study and need to be considered carefully. First, \(d_{vane,wall}\) is required to be sufficiently large so that the flow can travel through the gap and form a desired high-speed area in the downstream region. Second, \(d_{vane,vane}\) needs to be sufficiently low to shorten the unfavorable length of the low-speed area and to prevent this area from reaching the model test region. Third, \(d_{vane,model}\) must strike a balance so that it is not too large to cause the attenuation of the twist characteristics and not too small to allow the low-speed region to reach the model test region. 3. The numerical wind tunnel testing has demonstrated its applicability in providing valuable information for optimizing the experimental setups in the actual wind tunnel. By implementing passive devices in the actual wind tunnel following the setup used in its numerical counterpart, the desired TWF profiles have been generated with satisfying accuracy, i.e., the profiles of wind speed and turbulence intensity follow the power-law model for typical ABL winds, while the twist angle profile follows the Ekman spiral model. These results underscore the importance of utilizing numerical simulations to aid in the design of experimental setups, especially for novel devices such as the guide vane system discussed in the present study. Figure 20: Wind spectra of TWF at \(z=1.0\) m: (**a**) longitudinal speed; (**b**) lateral speed. **Author Contributions:** Conceptualization, Z.Y., X.L., Z.Z. and B.Y. ; methodology, Z.Y., X.L. and Z.Z. ; software, L.W. ; investigation, L.W., X.L. and X.Z. ; resources, B.Y. ; writing--original draft preparation, L.W. ; writing--review and editing, Z.Y. and X.L. ; supervision, B.Y. ; project administration, B.Y. ; funding acquisition, B.Y. All authors have read and agreed to the published version of the manuscript. This research was funded by the National Natural Science Foundation of China (No. 51878104 and No. 52278483), the Graduate Research and Innovation Foundation of Chongqing, China (CYB21028), and the 111 Project of China (B18062). Not applicable. The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy. The authors declare* [PERSON] et al. (2019) [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] Wind tunnel simulation of wind flows with the characteristics of thousand-meter high ABL. _Build Environ._**2019**, _152_, 74-86. [CrossRef]
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