## 4 Discussion and Conclusions  
In this work, numerical calculation was used in order to study an [PERSON] body model. The purpose of the work was to build a numerical model using two turbulence models, \(k-\omega\) SST and LES, as well as its verification based on experimental measurement data. The model quality was verified in two stages. The first stage was to prepare and ensure the good quality of the constructed computational mesh. The boundary layer was defined with a corresponding parameter \(y+\), which was around 1. The growth ratio between the elements was set at 1.15. The minimum orthogonal quality parameter was 0.323, while the aspect ratio did not exceed 60. The second stage of the model verification consisted in comparing the simulation calculation with the experimental measurement data, as well as with the numerical results obtained by other authors. The main criterion adopted was the comparison of the streamwise velocity profiles in the symmetry plane and the drag coefficient \(C_{d}\). In addition, the steady-state calculation confirmed the characteristic structures formed behind the vehicle model. The numerical model developed in the work, using the LES turbulence model, is of good quality. The two-stage research process related to the development of the model and the verification by experimental study allows to clearly state that the developed numerical model is correct. Further CAA analysis was possible using the FW-H analogy.  
FFT analysis transformed pressure versus time characteristic to frequency domain. In order to reduce acoustic noise generated by the Ahmed body geometry it is important to eliminate high values of sound pressure levels from the frequency range of 180 to 1400 Hz.  
The introduced methodology of using a colormap to compare of results of velocity profiles simplified the analysis of troubling areas of the calculation grid. For further analysis using the \(k-\omega\) SST turbulence model the mesh in the wake area should be improved. In case of using the LES turbulence model the absolute velocity error was partly the result of the method used to average the results every 1305 time steps.  
When analyzing the drag coefficient in respect to other studies, the biggest relative errors were observed for higher velocities, especially for the LES turbulence model. This kind of problem could be related with insufficient quality and density of the mesh. One possible solution would be using adaptive mesh refinement for automatically increasing the density in high turbulence areas [21].  
Computing the steady-state flow using the \(k-\omega\) SST turbulence model and the setting results from this simulation as initial conditions for transient simulation was a useful method to reduce computation time. However, in order to evaluate computational resource reduction further calculation is needed.  
The study on an aeroacoustic numerical model of an [PERSON] body was performed as part of a calculation grant in CYFRONET on the computing cluster PROMETHEUS. The total used walltime exceeded 60,000 h, where the number of cores reached up to 24 for a single simulation. ANSYS Fluent software was used as a solver. Further calculations and visualizations of the results were made in MATLAB software.  
Created an aeroacoustic model of the [PERSON] body will be used in a future study on aerodynamic and acoustic phenomena connected with a moving column of vehicles.  
Conceptualization, W.M.H. and W.B.C.; methodology, W.M.H. and W.B.C.; software, W.M.H.; validation, W.M.H.; formal analysis, W.M.H.; investigation, W.M.H. and W.B.C.; writing--original draft preparation, W.M.H. and W.B.C.; review, W.B.C.; visualization, W.M.H. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
This research was conducted with support of the PL-Grid (Polish NGI) Consortium, coordinated by the ACC Cyfronet AGH, grant id: aia.  
The authors declare no conflict of interest.