## 5 Conclusions  
The paper assessed the accuracy of an AL aerodynamic model in aeroelastic simulations of WT and helicopter rotors. Comparisons are presented against a standard BEM model, a classical LL approach, and experimental data. In the first part, a detailed investigation of the numerical parameters was performed. For WT simulations, it was found that a number of 90 cells in the rotor radius provided a grid independent solution, whilst a three times coarser discretization is suggested for the  
Figure 46: Harmonic analysis of Twisting moment. Amplitude of frequencies with the highest energy content. Figure 47: Harmonic analysis of Twisting moment. Phase of frequencies with the highest energy content. actuator lines. For the helicopter simulations, a number of 8 cells in the blade chord was sufficient. Time step was defined based on the grid resolution and tip velocity. The Gaussian kernel was chosen to vary with the chord length, but a lower bound of twice the grid spacing was set in order to avoid a too small kernel value at the blade tip. In the WT case, comparisons between the AL module, a standard BEM model, and a LL approach were presented. At simple axial cases, good agreement was achieved by all three models in terms of loads and deflections prediction. Deviations occur between BEM and the other two models at yawed free-stream flow conditions. These differences become more pronounced as the yaw angle increased. However, excellent agreement between AL and LL was observed in all the examined cases. In contrast to LL, AL predicted wake-induced velocities that tended to a zero near blade tip. The same difference between these two models was observed in the circulation close to the blade root. For the Helicopter MR simulations, AL predictions were validated against LL simulation results and wind tunnel measurements of the HeliNOVI experiment. In general, predictions were close to the experimental measurements and when differences occur the two models results seemed to agree well with each other. Nevertheless, at low speed cases, in which wake-induced effects were stronger, the AL model achieved a better phase agreement with experimental data and greater aerodynamic damping. Overall, AL results shared the same level of accuracy with the ones produced by the LL method. Although much more affordable than resolving the whole blade geometry, AL simulations remain at least 2 orders of magnitude more computationally demanding than LL. The main advantage of the AL method compared to LL, is that the rotor wake interaction with the boundary layer of the surrounding bodies (WT-Ground/Tower or MR-Ground/Fuselage) can be accounted for in detail within the CFD context. Moreover, vibrational blade loads induced by the flow separation around the fuselage may be accurately reproduced and studied. Conceptualization, V.A.R. ; methodology, N.S., G.P., J.M.P. and V.A.R. ; software, N.S., G.P., J.M.P. and V.A.R. ; validation, N.S., G.P., J.M.P. and V.A.R. ; formal analysis, N.S. ; investigation, N.S. ; resources, G.P., J.M.P. and V.A.R. ; data curation, N.S. ; writing--original draft preparation, N.S. ; writing--review and editing, N.S. and V.A.R. ; visualization, N.S. ; supervision, V.A.R. ; project administration, V.A.R. ; funding acquisition, N.S. All authors have read and agreed to the published version of the manuscript. The research work was supported by the Hellenic Foundation for Research and Innovation (HFRI) under the HFRI PhD Fellowship grant (Fellowship Number: 797). Data Availability Statement: Data supporting reported results can be provided upon request to the corresponding authors. NTUA computations were supported by computational time granted from the Greek Research & Technology Network (GRNET) in the National HPC facility-ARIS-under projects \"ELASTURB\" with ID pr005019_thin and \"ELASTODYN\" with ID pr010013_thin. The computational grids were generated using the ANSA CAE pre-processor of \"BETA_CAE Systems S.A.\". The authors declare no conflict of interest.