## 4 Conclusions  
This work investigated Darieu-type 500 W straight-bladed Vertical axis wind turbine (VAWT) using XFlow commercial software, using a meshingless Lattice Boltzmann method for different turbulence models in fine and coarse lattices.  
To assess the validity of the proposed numerical modelling, offering the meshingless lattice Boltzmann method, which users can avoid the remeshing process for CFD simulation, enables the investigation of the aerodynamic performance of wind turbines with fewer lattices, saving time and computational costs.  
Firstly, the influence of different turbulence modelling approaches on solution time was investigated depending on lattice sizes. It appeared that the RANS model could give a faster solution than the LES approaches even when the number of lattices is increased. The increase in the number of lattices is not changing the solution time proportionally.  
Secondly, experimental data on torque coefficient obtained from [15] were compared with different turbulence models in fine and coarse lattices. LES models, WALE and Smagorinsky, demonstrated the best agreement with experimental data. Especially, Smagorinsky model can be useful when less computational cost is required, and WALE is a suitable turbulence model that best agrees with experimental data to capture the maximum torque and power coefficient as users analyse the VAWT at the fine lattices.  
The effect of turbulence models is achieved by the velocity and turbulence intensity contours at different TSR values. RANS and LES models give an observable wake structure behind the rotating blades, especially at maximum torque coefficient. However, the LES model is useful when compared to the result with experimental in fine lattices.  
The result is also given by investigating vorticity at maximum power coefficient at varying azimuthal angles. LES models exhibit considerable differences in the wake predictions when compared with RANS. LES-WALE model has more intense wake structures, it is the reasonable effect of the LES model constant and its operator based on the formula, including the rotation tensor.  
In addition, a comprehensive sensitivity analysis has been conducted to investigate the behaviour of VANTs further. Surprisingly, the study reveals that capturing the flow phenomenon does not require an excessively fine grid, despite the significant flow separation observed. The simulation results are compared with both numerical and experimental data, and although some discrepancies exist, they are relatively minor when using fine lattices.  
Moreover, the study highlights an interesting finding: the power performance of the VAWT increases as the TSR rises, particularly at low TSRs. However, at high TSRs, the interaction between vortices and blades becomes more prominent and significantly influences the blade's performance.  
Writing--original draft preparation, C.L.; supervision, E.A. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the Scientific Research Projects Commission (BAPKO) of Marmara University under grant number FEN-C-DRP-130515-0179.  
**Institutional Review Board Statement:** The study did not require ethical approval.  
**Informed Consent Statement:** The study did not involve humans.  
**Data Availability Statement:** The benchmark data is available at [PERSON]; [PERSON] Numerical study of the aerodynamic performance of a 500 W Darrieus-type vertical-axis wind turbine. Renew. Energy 2015, 83, 407-415.  
**Conflicts of Interest:** The authors declare no conflict of interest.