**5. Conclusions**

In this present work, a computational system was designed to analyze and optimize the operational conditions of a wind turbine and the flow field surrounding the rotor wake region. This work is intended to establish a computational framework from which to investigate wind farm layout, and to validate the simulation identifying parameters influencing the wake. The computational results match the selected experimental data for the radial and axial traverse in axial flow conditions. Even though there are minor numerical discrepancies, this CFD model is suitable to determine how design parameters (such as TSR, velocity, and pitch angle) affect the wake aerodynamic behavior. The level of agreemen<sup>t</sup> is very similar in comparison to those found in literature. Further improvements in the model could be achieved by refining the near wall resolution y+ for higher velocities, even though there is no variation of y+ in orders of magnitude for the velocity values tested in this work.

An extensive numerical effort has been performed in this research to provide new insights related to near wake aerodynamics, which are crucial to understand wake characteristics and consequently to propose improvements to wind farm layout. Such an extensive numerical effort specifically on near wake modeling had not been addressed in literature before. A detailed study provided numerical estimates on the impact of TSR on velocity deficit and turbulence intensity/turbulent kinetic energy on the near wake. CFD simulation demonstrates that the TSR and the pitch angle greatly influence the near wake behavior, affecting the velocity deficit and the turbulence intensity profile in this region. In the near wake region, the velocity deficit increases as the TSR increases, revealing an increase of 20% in the velocity deficit as the TSR varies from 6 to 10. This corresponds to an increased ratio of approximately 5% <sup>m</sup>·s<sup>−</sup><sup>1</sup> per dimensionless unit of TSR. The velocity in the wake increases at a rate of approximately 15% of the free-stream velocity per rotor diameter at the wake, regardless of the free-stream velocity applied. The TI peak increases as the free-stream velocity increases. Considering TSR = 6.6, a downstream position at 1D behind the rotor shows an increase of around 85% in the TI peak from U = 10 <sup>m</sup>·s<sup>−</sup><sup>1</sup> to U = 15 <sup>m</sup>·s<sup>−</sup>1, and 40% from U = 15m·s<sup>−</sup><sup>1</sup> to U = 24 <sup>m</sup>·s<sup>−</sup>1. This shows that there is a dependence of the TI behavior according to the free-stream velocity. The Pitch Angle can significantly influence the near wake aerodynamic behavior; however, the far wake will not be significantly affected if the pitch angle is close to the designed condition. Wake characteristics such as velocity deficit and TI could also be affected by the pitch angle, the TSR, and at further downstream distances. Our results give support to the notion that the near wake analysis is extremely relevant for the optimal positioning of wind turbines in a wind farm.

**Author Contributions:** Conceptualization, R.V.R. and C.L.; methodology, R.V.R and C.L.; software, R.V.R.; validation, R.V.R.; formal analysis, R.V.R.; investigation, R.V.R. and C.L.; writing—original draft preparation, R.V.R.; writing—review and editing, R.V.R. and C.L.; funding acquisition, R.V.R.

**Funding:** This research was funded by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), gran<sup>t</sup> number 249258/2013-7.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
