# Numerical Study on Aerodynamic Characteristics of High-Speed Planing Trimaran
## 3 Results and Discussion
### Comparison and Analysis of Resistance  
Tables 5 and 6 show the resistance of each model at each speed point after CFD simulation, and the drag reduction effect compared with the prototype hull. Among them, Table 5 shows the relevant data of the arc stern and Table 6 shows the relevant data of the square stern. Figure 13 shows the line charts of each model under each speed condition. Some valuable conclusions can be drawn by comparing the data within the table and between the tables. From the data in Tables 5 and 6, the drag reduction effect of each model can be seen intuitively. From the data, most models of the square stern can reduce the drag to a certain extent, but the effect is not obvious enough. Even the design of Model D produces more resistance than the prototype hull. For the model with same superstructure, it is obvious that the arc stern model has an obvious drag reduction effect. It can be considered that the arc stern can bring about an additional 20% drag reduction effect. If the shape of the arc stern is further studied, it may even produce more of a drag reduction effect. Figure 12: Streamline details of Model C01 and Model C02: (**a**) Model C01; and (**b**) Model C02. On the other hand, the conclusion of the comparison between the same stern models varies with the shape of the superstructure. For the square stern, the best drag reduction effect is Model B02, which can achieve about a 10% drag reduction effect in the working conditions of 10-19 m/s. With the increase of velocity, the drag reduction effect of the square stern model generally decreases. It can be considered that such a stern design is not suitable for ultra-high-speed planing crafts. Model C01 has the best drag reduction effect. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**V**} & \multicolumn{2}{c}{**M 0**} & \multicolumn{2}{c}{**Model A01**} & \multicolumn{2}{c}{**Model B01**} & \multicolumn{2}{c}{**Model C01**} & \multicolumn{2}{c}{**Model D01**} \\ \cline{2-10}  & \multicolumn{4}{c}{**Drag**} & \multicolumn{2}{c}{**Drag**} & \multicolumn{2}{c}{**Drag**} & \multicolumn{2}{c}{**Drag**} & \multicolumn{2}{c}{**Drag**} \\  & **R (N)** & **R (N)** & **Reduction** & **R (N)** & **Reduction** & **R (N)** & **Reduction** & **R (N)** & **Reduction** \\  & & & **Effect** & & **Effect** & & **Effect** & & **Effect** \\ \hline
10 & 1.576 & 1.544 & 2.03\% & 1.432 & 9.14\% & 1.490 & 5.46\% & 1.554 & 1.40\% \\
13 & 2.828 & 2.660 & 5.94\% & 2.540 & 10.18\% & 2.598 & 8.13\% & 2.782 & 1.63\% \\
16 & 4.307 & 4.120 & 4.34\% & 3.874 & 10.05\% & 4.064 & 5.64\% & 4.348 & \(-\)0.95\% \\
19 & 6.307 & 6.160 & 2.33\% & 5.666 & 10.16\% & 6.044 & 4.17\% & 6.568 & \(-\)4.14\% \\
22 & 8.260 & 7.800 & 5.57\% & 7.780 & 5.81\% & 7.844 & 5.04\% & 8.842 & \(-\)7.05\% \\
25 & 11.020 & 10.92 & 0.91\% & 10.54 & 4.36\% & 11.14 & \(-\)1.09\% & 12.672 & \(-\)14.99\% \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Resistance and drag reduction effect of square stern model. Figure 13: The resistance line charts of each model: (a) Resistance line chart of arc stern model under various speed conditions; (b) Resistance line chart of square stern model under various speed conditions. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**V**} & \multicolumn{2}{c}{**M 0**} & \multicolumn{2}{c}{**Model A01**} & \multicolumn{2}{c}{**Model B01**} & \multicolumn{2}{c}{**Model C01**} & \multicolumn{2}{c}{**Model D01**} \\ \cline{2-10}  & \multicolumn{4}{c}{**Drag**} & \multicolumn{2}{c}{**Drag**} & \multicolumn{2}{c}{**Drag**} & \multicolumn{2}{c}{**Drag**} & \multicolumn{2}{c}{**Drag**} \\  & **R (N)** & **R (N)** & **Reduction** & **R (N)** & **Reduction** & **R (N)** & **Reduction** & **R (N)** & **Reduction** \\
22 & 8.260 & 6.440 & 22.03\% & 6.334 & 23.32\% & 5.828 & 29.44\% & 7.496 & 9.25\% \\
25 & 11.020 & 8.440 & 23.41\% & 8.980 & 18.51\% & 7.718 & 29.96\% & 10.274 & 6.77\% \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Resistance and drag reduction effect of arc stern model.