# Wind-Load Response and Evacuation Efficiency Analysis of Marine Evacuation Inflatable Slide
## 3 Wind-Load Response Analysis of Inflatable Slide under Fluid-Solid Coupling
### Wind-Load Response of Emergency Inflatable Slide under Different Wind Direction Angles  
Different wind directions have great influence on the motion response of offshore structures. When a ship is in distress at sea, the most unfavorable wind direction can be obtained during the analysis of the deformation and wind pressure distribution data of its evacuation system caused by different incoming winds [16]. According to the size characteristics of the evacuation system involved in this paper, the geometrical size of the flow field area is set to 150 m \(\times\) 100 m \(\times\) 50 m. We set air pressure variable (4000 Pa) and wind speed variable (20 m/s), and carried out numerical simulation analysis. The layout of inflatable slide at different wind directions on the sea surface is shown in Figure 7.  
Due to the fluid-solid coupling response, the inflatable slide is deformed by wind loads, which in turn will give feedback to the wind pressure distribution on the surface of the inflatable slide [17]. The numerical simulation of the airflow field of the inflatable slide is carried out under different wind direction angles and the simulation results are obtained. The displacement and deformation of the inflatable slide under different wind directions are shown in Figure 8.  
Figure 8: _Cont._  
Figure 7: The layout of the inflatable slide at different wind directions on the sea surface. When the wind direction is 0\({}^{\circ}\), the maximum displacement deformation occurs on the surface of the inflatable slide and on the platform area, which is about 0.037 m. When the wind direction is 30\({}^{\circ}\), the maximum displacement occurs at the back of the slide, which is about 0.044 m. This deformation is also the maximum of the displacement deformation of the slide at each wind direction angle. When the wind direction is 60\({}^{\circ}\), the maximum displacement occurs on the surface of the landing platform of the inflatable slide, which is about 0.035 m. When the wind direction is 90\({}^{\circ}\), the maximum displacement deformation occurs at the back of the slide surface, which is about 0.032 m. The displacement extremes under different condition variables are summarized in Table 1.  
From the above simulation data, as shown in Figure 9, it can be seen that the different wind direction angles have great influence on the displacement deformation of the flexible inflatable membrane. Among the effects of each wind direction angle, the wind direction angle of 30\({}^{\circ}\) has the most obvious effect on the inflatable slide, and the displacement deformation is the largest. Wind pressure distribution in the wind field is an important factor to measure the stability of the emergency inflatable slide when it is laid out on the sea surface [18]. In the simulation process, if the wind pressure value is positive, then the wind pressure direction is vertical sliding surface inward, while the wind pressure value is negative, then the wind pressure direction is vertical sliding surface outward. In CFX fluid analysis, the distribution of wind pressure will be distinguished according to the numerical value [19]. The boundary of the same color area is called the isoline. The sparse and uniform distribution of the isoline represents the stable change of partial pressure, while the dense distribution of the isoline means the drastic change of wind pressure. As shown in Figure 10, Figure 11 and Table 2, according to the response analysis of the inflatable evacuation slide under different wind directions, it can be concluded that the maximum displacement deformation and the maximum positive pressure distribution are found in the slide with wind direction \begin{table}
\begin{tabular}{c c c c} \hline
**Wind Direction Angle** & **3000 Pa** & **4000 Pa** & **5000 Pa** \\ \hline
0\({}^{\circ}\) & 0.040 m & 0.037 m & 0.032 m \\
30\({}^{\circ}\) & 0.068 m & 0.044 m & 0.040 m \\
60\({}^{\circ}\) & 0.040 m & 0.035 m & 0.032 m \\
90\({}^{\circ}\) & 0.037 m & 0.032 m & 0.030 m \\ \hline \end{tabular}
\end{table}