## 5 Conclusions  
In this paper, the incompressible and compressible CFD methods are used to calculate the outflow field around the idealized side mirror when the air flow is 40 m/s, and a small panel behind the side mirror is selected to simulate the size of the side window and analyze the fluctuating pressure of the idealized side mirror. Based on the results of the incompressible numerical simulation, three methods (Corcos, random modal force and deterministic modal force) are used to extract the convection  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multirow{2}{*}{**Method**} & \multicolumn{3}{c}{**Calculation Time of Each Step**} & \multicolumn{1}{c}{**Total Time**} \\ \cline{3-6}  & & \(t_{1}\) & \(t_{2}\) & \(t_{3}\) & \(t_{4}\) & \(t\) \\ \hline \multirow{2}{*}{\
\begin{tabular}{c} Incompressible \\ computation \\ 5 days \\ \end{tabular} } & Corcos coupling BEM & 668.5 s & 90.3 s & 40 h & 0.34 s & 160.211 h \\  & Deterministic modal force & 667.01 s & 104.63 s & 40 h & 252.97 s & 160.285 h \\  & Random modal force & 660.13 s & 104.63 s & 40 h & 247.04 s & 160.281 h \\ \hline \multirow{2}{*}{
\begin{tabular}{c} Compressible \\ Computation \\ 16 days \\ \end{tabular} } & Wavenumber decomposition & 259.53 s & 54.22 s & - & 0.23 s & 384.087 h \\  & Deterministic modal force & 667.01 s & 104.63 s & - & 95.90 s & 384.241 h \\  & Random modal force & 660.13 s & 104.63 s & - & 114.08 s & 384.244 h \\ \hline \hline \end{tabular}  
* \(t_{1}\): Reading Pulsating Pressure Data and Fourier transform. \(t_{2}\): Extraction of Convective Component. \(t_{3}\): Extraction of acoustic Component. \(t_{4}\): Calculated the radiated SPL. \(t\): Total time.  
\end{table}
Table 3: Computational time comparison of each method.  
component. The Lighthill Curle coupling BEM method is used to calculate the acoustic component of the panel. It is found that the amplitude of the acoustic component first decreases and then increases with the frequency. Then, the corresponding vibro-acoustic model is established under three different methods (Corcos model coupling BEM, random modal force coupling BEM, deterministic modal force coupling BEM), and the radiation noise of the panel under the aerodynamic excitation is studied. Based on the numerical simulation of the compressible flow field, the convection component and acoustic component in the fluctuating pressure are separated by the WFS method, and then three different methods (TBL coupling DAF, random modal force, deterministic modal force) are used to calculate the radiated noise of the panel. Finally, the results of six methods with the experimental results are compared, and the calculation time of six methods, the compressible and incompressible, are analyzed. Considering the calculation time and the accuracy of the calculation results, it is considered that it is a fast and accurate method to obtain the FSP using the incompressible numerical simulation method and the random modal force coupling BEM method, which are more balanced in the calculation time and efficiency.  
Conceptualization, J.S. and X.W.; Data curation, J.S., J.Y., C.W. and G.D.; Formal analysis, J.S., C.W. and G.D.; Investigation, J.S. and J.Y.; Methodology, J.S. and X.W.; Project administration, J.S.; Resources, J.S. and X.W.; Supervision, X.W.; Validation, J.S., J.Y., C.W. and G.D.; Visualization, J.S.; Writing--original draft, J.S. and J.Y.; Writing--review and editing, J.Y. and J.S. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Natural Science Foundation of China [grant number No. 51805372]; the Natural Science Foundation of Shanghai [grant number No. 18 ZR1440900].  
The authors declare no conflict of interest.