## 4 Results and Discussion
### Effect of Flow Distribution on the WSM  
#### 4.2.1 Structural Deformation When the Rake Is Not Operational  
The main screen, sub-screen, and the rake, along with the mechanisms that are used to lift the sub-screen and operate the rake, comprise a deformable material and thus would bend under an applied force. This deformation would negatively affect the screening  
Figure 11: Velocity profile along the x-direction for the inlet velocity of 0.2 m/s when the rake is operational and (**a**) \(\varphi_{\text{r}}=-75^{\circ}\); (**b**) \(\varphi_{\text{r}}=0^{\circ}\); the arrows represent the horizontal component of the velocity at the trailing points.  
process by disturbing the desired positions of the WSM components. Therefore, the deformation in the WSM components due to the flow distribution was investigated.  
The normalized deformation contour plots of the main screen and the sub-screen due to the flow distribution when the sub-screen is fully lowered are presented for the inlet velocities of 0.1 and 0.3 m/s in Figure 13a,b and for the partially lowered case in Figure 13c and d, respectively. Notably, the main screen does not undergo significant deformation in any case due to the support of the wall at the lower end and near the top surface of the water. However, the fluid forces substantially deform the sub-screen, especially the upper-middle region. This deformation profile is similar in the fully and partially lowered cases.  
Figure 12: Effects of rake on the velocity magnitude at posterior position (\(\varphi_{\text{r}}=-75^{\circ}\)) and vertical position (\(\varphi_{\text{r}}=0^{\circ}\)) in the (**a**) upstream region (location C) and (**b**) downstream region (location D).  
Figure 13: Normalized deformation contour plots of the main screen and sub-screen when the sub-screen is fully lowered for (**a**) U = 0.1 m/s and (**b**) U = 0.3 m/s and partially lowered for (**c**) U = 0.1 m/s and (**d**) U = 0.3 m/s.  
The deformation of selected bars of the sub-screen, plotted on the FSI boundary of the sub-screen in Figure 14, for when the sub-screen is fully lowered is presented for the inlet velocities of 0.1 and 0.3 m/s in Figure 14a,b and for the partially lowered case in Figure 14c,d. The legend in the graph shows the selected bars of the sub-screen. B1, B6, B12, and B18 represent the 1 st, 6 th, 12 th, and 18 th bar of the sub-screen, respectively. h represents the displacement on the FSI boundary of the sub-screen starting at the bottom of the sub-screen, whereas h\({}_{\rm ss}\) represents the total length of the FSI boundary. The bending of the sub-screen is slightly increased for high flow rates. The higher flow velocity causes the drag force to be larger, resulting in a larger deformation of and high stresses in the WSM components. However, the intensity of deformation bending is unaffected whether the sub-screen is fully or partially lowered. It is noted that the present 3D study provides a comprehensive deformation profile across the entire bar set (B1, B6, B12, and B18), as depicted in Figure 14, and enables the examination of deformation in various sub-screen bars. This builds upon the analysis carried out by [PERSON] et al. [7], whose similar study was focused on the 2D case. Figure 14 further shows that the spatial deformation rate of the sub-screen increases over the length of its bars. This finding reveals the favorability of a small height of the sub-screen.