## 6 Conclusions  
This work presents a comparative study on the prediction of the pressure loss in a system composed of two dissipative splitter silencers embedded in a duct by using standards (ISO 14163 and VDI 2081-1), numerical simulations (FEM) and experimental measurements. The consideration of two different profile shapes in the silencers and four different input face velocities show the importance of these factors in the resulting pressure loss, as they can strongly modify the behavior of the flow in the duct. The simulations performed by means of the FEM also show a significant improvement in the predicted results compared to both standards when semihexadecagonal profiles are considered and, at the same time, demonstrate a similar performance in the calculation of the pressure loss for rectangular profiles than the ISO standard. The results obtained by means of the FEM also show their feasibility in the prediction of the pressure loss of dissipative splitter silencers in ducts, especially in those cases that are not considered in the standards. Additionally, the FEM-implemented simulations tend to slightly overestimate this value and, consequently, the results allow a safety buffer in the design of these devices.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**U\({}_{0}\) [m/s]** & **ISO 14163** & **VDI 2081-1** & **FEM** \\ \hline
5 & \(-21\) & \(-16\) & \(12\) \\
10 & \(-78\) & \(-69\) & \(25\) \\
15 & \(-167\) & \(-164\) & \(55\) \\
20 & \(-287\) & \(-301\) & \(123\) \\ \hline \hline \end{tabular}
\end{table}
Table 6: Difference between the predicted pressure loss (in Pascals) obtained with ISO 14163, VDI 2081-1 and FEM with that of experimental measurements for the system of splitters with semihexadecagonal profiles.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**U\({}_{0}\) [m/s]** & **ISO 14163** & **VDI 2081-1** & **FEM** \\ \hline
5 & \(29\) & \(8\) & \(47\) \\
10 & \(4\) & \(-83\) & \(66\) \\
15 & \(-77\) & \(-272\) & \(83\) \\
20 & \(-212\) & \(-560\) & \(141\) \\ \hline \hline \end{tabular}
\end{table}
Table 5: Difference between the predicted pressure loss (in Pascals) obtained with ISO 14163, VDI 2081-1 and FEM with that of experimental measurements for the system of splitters with rectangular profiles.  
**Author Contributions:** Conceptualization, B.C.; methodology, B.C. and I.H.-D.; software, I.H.-D.; validation, B.C. and I.H.-D.; formal analysis, B.C., I.H.-D. and P.N.; investigation, B.C., I.H.-D. and P.N.; resources, B.C.; data curation, B.C. and I.H.-D.; writing--original draft preparation, I.H.-D.; writing--review and editing, B.C., I.H.-D. and P.N.; visualization, I.H.-D.; supervision, B.C. and I.H.-D.; project administration, B.C.; funding acquisition, B.C. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by Narodowe Centrum Badan i Rozwoju (NCBR) under the project POIR.01.01.01-00-0852/18 \"Development of the innovative line of \"Rocket\" and \"Rocket-Active\" types of silencers, aimed at implementing a series of next-generation acoustic products\".  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**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.