## 5 Conclusions  
This paper computationally investigates the FSI between the WSM and sewage water flow to improve the screening process. A two-way coupling methodology was adopted to compute the flow of water through the WSM components. Two different configurations of the WSM were considered: one with the fully lowered sub-screen (\(\epsilon_{\text{ss}}=0\) m) and another where the sub-screen is partially lowered (\(\epsilon_{\text{ss}}=0.55\) m). Furthermore, two different stages of the rake movement were presented: one with the rake in the vertical position (\(\varphi_{\text{r}}=0\)) and the other with the rake at the posterior end of the WSM (\(\varphi_{\text{r}}=-75^{\circ}\)). The flow behavior in the upstream and downstream sections of the sewage channel was reported to examine the effect of the WSM on the water flow. The subsequent effect of water flow on the WSMcomponents was also studied by computing the structural deformation of and the von Mises stresses in the WSM components. The main conclusions of the study are summarized as follows:  
* The flow distribution remains uniform after it passes through the WSM when the sub-screen is fully lowered and the rake is not operational. However, the flow separation in the case of a partially lowered sub-screen traverses until the end of the channel. Furthermore, the average cross-sectional velocity at the outlet is uniform when the rake is operational, but its magnitude fluctuates significantly. The average cross-sectional velocity at the outlet is reduced by 0.60% in the case where the sub-screen is fully lowered and by 0.71% in the case where the sub-screen is partially lowered. * The sub-screen is deformed especially at the upper mid-region. Moreover, the spatial rate of deformation of the sub-screen increases over the length of its bars. The fluid forces induce fluctuating deformation in the rake throughout its operation. Specifically, the deformation and von Mises stresses in the rake are significantly higher in the posterior position than in the vertical position. * The findings of the study have practical implications for engineers in material selection and structural design. Particularly, the significant fluctuations in the average cross-sectional velocity will result in unsteady stress application on the WSM components, especially when the rake movement mechanism is operational. Therefore, engineers must consider the dynamic loading conditions in their designs to avoid structural failures. Similarly, there are broader implications for wastewater treatment practitioners related to awareness about uneven stress distributions on the WSM, as this information will be crucial for the maintenance of WTP. While the present study extends the available 2D research into 3D and attempts to present a comprehensive analysis of the screening components, it can be extended in several ways. For instance, the study did not include the supporting frame of the main screen and the sub-screen, as well as the rake movement mechanism, due to limitations in computational time. Including these components will help us understand the full interaction of all components in the WSM and thus improve the accuracy of the computations. Furthermore, the study primarily analyzed flow separation, structural deformation, and von Mises stresses. This focus leaves out other potential areas of interest, such as different types of solid waste that pass through the screen and chemical changes to the structural steel used due to a long-term interaction with water. These changes could affect the long-term operational efficiency and have implications for the sustainability of the WSM. Thus, future studies may include the additional WSM components, the analysis of solid waste, and the investigation of the sustainability and environmental aspects of the WSM. Conceptualization, S.A., S.A.M. and C.-W.P. ; methodology, S.A. and S.A.M. ; software, S.A., S.A.M. and C.-W.P. ; validation, S.A.; formal analysis, S.A. and S.A.M. ; investigation, S.A. and S.A.M. ; resources, H.-B.C., D.-W.C. and C.-W.P.