## 6 Conclusions  
This study evaluated the performance of numerical simulations in replicating the behavior of a high-velocity free-water jet (\(V_{i}=7.4\) m/s) impacting a plunge pool (\(\gamma=0.8\) m). Two solvers, interFoam (VoF approach) and twoPhaseEulerFoam (Euler-Euler approach), were tested. Results were compared against experimental data collected at LNEC, where pressures were measured at 19 locations with acquisition rates of 600 Hz.  
**(A) Solver comparison and key findings**  
Mesh resolutions: TwoPhaseEulerFoam demonstrated mesh independence for mean dynamic pressure and air concentration, while interFoam showed mesh dependency, especially at the jet stagnation point. The following additional conclusions are pointed out:  
* Different mesh resolutions were tested and labeled as D6, D12, D24, and D36, corresponding to meshes containing 6, 12, 24, and 36 cells along the jet diameter.  
* TwoPhaseEulerFoam accurately simulated mean dynamic pressures with D24 and D36 meshes. For regions outside the jet stagnation point, acceptable results were achieved with D12 meshes.
* Both solvers predicted velocity fields higher than experimental values but remained comparable to each other.
* TwoPhaseEulerFoam provided more accurate and mesh-independent air concentration results, outperforming interFoam, whose VoF formulation struggled. **(B) Boundary layer and computational efficiency** Including a boundary layer had minimal impact on pressure results but significantly increased simulation time. Therefore, the D24 mesh was chosen as optimal, balancing accuracy and computational cost. **(C) Turbulence and pressure fluctuations**
* Variations in turbulence intensity influenced pressure at the jet stagnation point, with differences of up to 26%. Outside this zone, turbulence effects were less pronounced.
* TwoPhaseEulerFoam coupled with the k-OmegaSST model cannot directly simulate pressure fluctuations. However, fluctuations derived from turbulent kinetic energy aligned well with experimental data, highlighting the solver's potential with further refinements. **(D) Velocity profile and flow zones**
* Core zone: Persistent jet velocity over \(5.0D_{i}\), consistent with prior studies.
* Established flow zone: Linear velocity decrease properly captured by the adopted numerical approach.
* Impingement zone: The velocity slope matched well with the findings of the literature.
* The study results point out the adequacy of the twoPhaseEulerFoam solver as a reliable tool for simulating jets in plunge pools, especially when:
* Accurate dynamic pressure and air concentration results are needed.
* Computational efficiency is a priority, as mesh independence is achieved with coarser meshes than with the interFoam-VoF solver.  
Conceptualization, A.M., J.F.M. and H.M.R.; methodology, A.M., J.F.M. and H.M.R.; software, A.M.; validation, A.M.; writing--original draft preparation, A.M., J.F.M. and H.M.R. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by Fundacao para a Ciencia e Tecnologia (FCT), Portugal, grant number PD/BD/135593/2018. Infraestrutura Nacional de Computacao Distribuida (INCD) funded by FCT and FEDER (European Regional Development Fund) under the project CPCA/A2/7192/2020, Portugal, computational resources. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** Data will be made available on request. **Conflicts of Interest:** The authors declare no conflicts of interest.