## 3 Results and Discussion
### Simulation Results and Analysis of S-U-S
#### 3.1.3 Comparative Analysis of Drag Reduction Bionic Structures  
The simulation results obtained by the aforementioned test methods show that, under the appropriate structural parameters and arrangement spacing, the bionic digging shovel can achieve excellent antiadhesion and drag reduction performance. Especially in the case of \(S_{1}=S_{2}=1\) mm, the bionic digging shovel can achieve optimal drag reduction performance. The drag reduction performances of S-U-S-I/\(\hbar\)3.5 and the O-P-S are listed in Table 6.  
The simulated results indicate that the bionic digging shovel had an excellent drag reduction performance. Compared with the O-P-S, the drag reduction rate of S-U-S-I/\(\hbar\)3.5 was larger than 24%.  
For the drag reduction phenomenon, the velocity flow of the simulated soil particles can be explained. Figures 13 and 14 shows the velocity flow of soil particles on the O-P-S and S-U-S-I/\(\hbar\)3.5, respectively. As shown in Figure 13, the velocity flow of the soil particles on the O-P-S were disorganized and the number of green arrows was also less than that of the bionic shovel. Moreover, the velocity of soil particles was mostly less than 0.788 m/s (green and blue arrows shown in Figure 13. It is notable that the speed of the shovel is 0.84 m/s. However, the speed of the soil particles moving on the O-P-S was generally less than that of the shovel. This finding obviously indicated that the soil particles were deposited on the shovel, which led to an overall decrease in the velocity flow and the possibility of blocking the movement of the soil particles. This result explained why the resistance of the O-P-S was larger than that of the bionic shovel. Similarly, as shown in Figure 14, the soil particles on the bionic shovel show a good fluidity (with attention to the direction of the arrow, the flow of the arrows is consistent.). The velocity flow of the particles was greater than the 0.84 m/s movement speed of the shovel. The velocity flow of the S-U-S-I/\(\hbar\)3.5 was approximately 0.942 m/s. This finding indicated that the soil particles on the bionic shovels presented good fluidity. High kinetic energy can cause the soil particles on the shovel surface to avoid siltation. Therefore, the bionic shovel exhibits a good antiadhesion and drag reduction performance.  
As shown in Figures 15 and 16, the time ranging from 17 s to 26 s can be regarded as the steady working time of the shovel. To analyze the drag reduction performance of the bionic shovel and the ordinary shovel, the average values of the testing results were analyzed at 17-26 s, respectively, as listed in Table 7.  
Table 7 clearly shows that the average traction resistance of O-P-S was 1117.78 \(\pm\) 32.88 N and the average traction resistance of S-U-S-_I7h_3.5 was 868.95 \(\pm\) 38.20 N. It was calculated that the drag reduction rate of S-U-S-_I7h_3.5 was 22.26% compared to the O-P-S. Hence, it can be concluded that the S-U-S-_I7h_3.5 had a better drag reduction performance than the O-P-S.  
In summary, the physical verification test fully indicated that the bionic design of the digging shovel was feasible. This result laid the foundation for a systematic design and further research on the bionic digging shovel in the future.