## 4 Result Discussion and Analysis
### Comparative Analysis of Existing Drag Calculation Formulas and Experiments
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Water Depth (m)**} & \multirow{2}{*}{\begin{tabular}{c} **Water Depth Draft** \\ **Ratio h/T** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Tunnel Section** \\ **Coefficient n** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Towing** \\ **Speed (m/s)** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Froude** \\ **Number Fr** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Total Resistance** \\ **(kN)** \\ \end{tabular} } \\ \hline \multirow{4}{*}{5.5} & \multirow{4}{*}{1.49} & \multirow{4}{*}{2.10} & 0.5 & 0.41 & 933.50 \\  & & & 1.0 & 0.48 & 1112.88 \\  & & & 1.5 & 0.54 & 1517.56 \\  & & & 2.0 & 0.61 & 1937.64 \\  & & & 2.5 & 0.68 & 2336.94 \\ \hline \multirow{4}{*}{6.0} & \multirow{4}{*}{1.62} & \multirow{4}{*}{2.29} & 0.5 & 0.39 & 591.14 \\  & & & 1.0 & 0.46 & 695.10 \\ \cline{1-1}  & & & 1.5 & 0.52 & 984.86 \\ \cline{1-1}  & & & 2.0 & 0.59 & 1524.58 \\ \cline{1-1}  & & & 2.5 & 0.65 & 2096.95 \\ \hline \hline \end{tabular}  
* B/b is the ratio of channel width to ship width.  
\end{table} 
Table 9: _Cont._experiment, it can be seen that the above empirical resistance estimation formulas have significant differences from the parameters B/b, section coefficient, and ship tonnage of this experiment. Therefore, the empirical resistance estimation formulas in the table are not applicable to the resistance calculation in this experiment. Table 11 presents the resistance calculation values from various existing resistance calculation formulas and the resistance test values of the towed navigation tunnel. However, due to the sudden changes and negative values calculated by [PERSON] and [PERSON]'s restrictive channel resistance calculation formula, the resistance calculation is meaningless and, therefore, specific results are not shown. The comparison between each formula and the resistance values of the towed navigation tunnel test is shown in the following figure through Table 11:  
Figure 9 shows that the trend of resistance results for the towed navigation tunnel is consistent with the trend of resistance calculation results from various formulas, both increasing with the increase in speed. However, the resistance value of the former is much greater than that of the latter. 1. It is certain that the resistance test values of the towed navigation tunnel are greater than the calculated values of other formulas. In the narrow and long tunnel with a small section coefficient, the water level in front of the ship body is high, and the water level in the rear is low, which increases the slope resistance of the ship. The increase in the relative flow velocity around the ship leads to the increase in the friction resistance and the residual resistance. At the same time, the superposition of the scattered wave of the side wall and the ship wave makes the wave resistance increase. Therefore, under the condition that the influencing factors increase and enhance, the resistance of the towed navigation tunnel and the calculated values of the existing formulas will increase by several times or even ten or a hundred times. 2. The resistance calculation results of the Zwankov formula and the Yu Zhongqi fitting formula differ by a factor of 7 to 53 times from the experimental values. In still water, as the speed increases, the resistance calculation results also increase.