*3.1. Flow Field Static Simulation Analysis of Seeding Device*

The fluid domain was imported into ANSYS FLUENT, and the hexahedral meshing method was used to mesh the nine groups of the fluid domain in the experiment scheme. Since there was no need to solve the viscous bottom layer, we used the wall function method to solve the simulation [35–37]. The divided fluid domain contained about 1 million meshes under the simulation parameter of five boundary layers and a 1.2 mesh growth coefficient. The mesh quality was good, with a minimum orthogonal quality is above 0.5 and a maximum aspect ratio of less than 10. The fluid domain is shown in Figure 7.

**Figure 7.** Fluid domain meshing: (**a**) overall meshing diagram; (**b**) meshing diagram for seed-sucking hole.

θ

According to the above theoretical analysis, it can be concluded that the diameter (*dh*) of the horizontal air pipe, the angle (*θ*) of the air pipe, and the diameter (*dz*) of the negative pressure aperture have a significant influence on the pressure loss in the airway. Taking the above three parameters as the experimental factors, a three-factor three-level orthogonal simulation experiment was designed. The experiment factors and levels are shown in Table 1.

**Table 1.** Experiment factors and levels.


The airflow velocity at the seed-sucking hole was used as the core index to measure the performance of the seed sucking, so the seed-sucking holes' average airflow velocity, the minimum airflow velocity, and the airflow velocity standard deviation were selected as the experiment indicators. There were 12 sets of data on seed-sucking holes for each set of simulations. The airflow velocity at the center of the seed-sucking hole was taken as the experiment results. The standard three-factor three-level orthogonal table was selected and simulations were carried out. The method of steady-state calculation and the model of standard k-epsilon turbulence in Fluent were used. The pressure inlet boundary was set at −7 kPa, the outlet boundary condition was the pressure outlet boundary, and the pressure was 0 Pa. The solution method used was the SIMPLE method. The simulation results are shown in Table 2.

**Table 2.** Simulation experiment results.

