## 4 Wind Pressure Characteristics with Different Vortex Isolation Plates
Based on the information presented in Figure 8, it is clear that the use of vortex isolation plates with different opening ratios has a significant effect on the heave. Specifically, while the trend in the average pressure coefficient is similar in zones D-1 to D-5 at different opening ratios, there are notable differences in zones U-1 to U-4. Combined with Figure 4e, when the average pressure coefficient fluctuates significantly in the U-1 to U-4 region, the heave of the section disappears. This suggests that changes in the opening ratio can have a significant impact on the pressure distribution in the upstream section, which in turn affects the occurrence of heave. In comparison to other opening ratios, at opening ratios of 48.68% and 64.36%, the fluctuating pressure coefficient exhibits a noticeable jump phenomenon in zones D-2 and D-3, which in turn results in significant heave. During heaving, the frequency at each pressure tap approaches the natural frequency. Conversely, when the section exhibits disorderly vibrations, the frequency at each pressure tap tends to be close to the high-frequency multiplication or near 0. Furthermore, when the frequency amplitude changes significantly in zones D-1 to D-3 and displays a jumping phenomenon in zones D-2 and D-3, a noticeable heave occurs. Based on the above-mentioned observations, we conclude that the heave control zones in the twin box are U-1 to U-4 and D-1 to D-3. This conclusion is based on the fluctuation in the average pressure in the upstream section, the  
Figure 7: The intrinsic characteristics of the original section. (**a**) Average pressure coefficient; (**b**) fluctuating pressure coefficient; (**c**) frequency; (**d**) frequency amplitude. jump in the fluctuating pressure in the downstream near the slot, the frequency distribution at each pressure tap, and the change in the downstream frequency amplitude. The torsional vibration characteristics at different opening ratios are shown in Figure 9. The average pressure in D-2 to D-5 exhibits irregular variations. Notably, the leading edge of D-2 and D-3 exhibits a step-like change and a sudden drop occurs in the second half of D-3, followed by a \"w\"-shaped distribution of pressure. Furthermore, there is a sharp decline at the junction of U-4 and U-5, and an increasing trend at U-5, which is similar to that at D-5. This phenomenon suggests that a fixed separation point can significantly affect the surface pressure. Considering Figure 5e, there are two different distribution forms for torsional vibrations and disorder vibrations in the D-1 region. Specifically, in the presence of torsional vibrations, the fluctuating pressure at D-1 increases as the pressure tap is further away from the slot. On the other hand, disorder vibrations generally exhibit a downward trend. There is a clear jump phenomenon present in zones D-2 and D-3, which is similar to the observed heave. We believe that this jump phenomenon may be caused by the periodic impingement of the vortex in the slot at the front of the downstream section. Based on these observations, when the section experiences torsional vibrations at different opening ratios, the pressure taps tend to lock around the torsional natural frequency. However, when the vibrations become disordered, there are multiple different frequencies. Furthermore, the frequency amplitude and fluctuating pressure distributions exhibit a similar trend, with both exhibiting significant spreads and a jump in the downstream section near the slot. Figure 8: Intrinsic heaving characteristics at different opening ratios. (**a**) Average pressure coefficient; (**b**) fluctuating pressure coefficient; (**c**) frequency; (**d**) frequency amplitude.