# Drift Potential Characteristics of a Flat Fan Nozzle: A Numerical and Experimental Study
## 4 Results and Discussion
### Comparison and Analysis of Data and Results
For the droplet deposition amount, 2 m downward in the wind direction and beyond, it gradually decreases from front to back under all conditions, whereas the 3 m/s lateral wind speed decreases and changes faster than the drift rate of 6 m/s. According to the linear fitting of the deposition quality of V1 (H2) and H3-H15 polyethylene lines and straight-line fitting of the deposition quality, the droplet deposition quality was 0.04 mL/(min\(\cdot\)cm\({}^{2}\)). The distance is the drift distance, and its statistics are summarized in Table 3.  
Figure 9: Quality of rhodamine-B on polyethylene wire under the influence of crosswinds with varying speeds. (**a**) Lu 120-015 with spray pressure is 0.3 MPa; (**b**) Lu 120-015 with spray pressure is 0.4 MPa; (**c**) Lu 120-03 with spray pressure is 0.3 MPa. A comparison of the drifts under the three different spraying conditions showed that, at a spraying pressure of 0.3 MPa, and when the horizontal wind speed increased from 1 m/s to 3 m/s, the drift distance increased rapidly from less than 4 m to more than 15 m. However, it increased marginally with the increase in wind speed from 3 m/s to 6 m/s. For the same nozzle (Lu 120-015), the droplet size subtly decreased as the spraying pressure increased, and the drift distance increased simultaneously under the same wind speed. According to the analysis, the drift distance is related to the coupling between droplet size and number. Without considering polymerization and evaporation, the settling time for droplets with the same particle size in the air was fixed, which is affected by air resistance. The deposition time of large droplets was shorter than that of small ones. The droplets evaporated while drifting downwind under the influence of horizontal wind. Large droplets more easily settled on the ground and had a stronger anti-evaporation ability that helped them avoid precipitation of the effective components within them. Tiny droplets completely evaporated before settling on the ground. Therefore, when the influences of evaporation and polymerization are considered, the number of droplets and the distance between them will affect their evaporation and aggregation, affecting the drift distance. The wind speed of 1 m/s had a clear effect on the drift of small droplets. Consequently, the drift amount and distance were limited. As the wind speed increased to 3 m/s and 6 m/s, the drift amount and distance increased rapidly. For the spray pressure of 0.3 MPa, the characteristic height \(h\) of the droplet drift distribution under three lateral wind speeds were calculated as H\({}_{1}\) = 0.175 m, H\({}_{3}\) = 0.2 m, and H\({}_{6}\) = 0.245 m, and the horizontal drift rates were \(R_{h1}\) = 0.4%, \(R_{h3}\) = 48.1%, and \(R_{h6}\) = 75.1%. Furthermore, the simulated drift data were obtained by estimating the discrete-phase deposition quality per unit distance on the bottom surface in the simulation result file. Within this distance, the drift data were deduced from the quality of rhodamine-B deposited on the polyethylene line arranged horizontally in the wind tunnel. The drift data at different distances under the same lateral wind speed between the simulation and the test are compared in Table 4. The analysis reveals that the data correlations of the drift amount and distance at 1 m/s, 3 m/s, and 6 m/s between the simulation and experiment were 0.905, 0.995, and 0.978, respectively. Furthermore, data of the horizontal drift rate from simulation (\(R_{hs}\)) and wind tunnel test (\(R_{ht}\)) at different lateral wind speeds were compared using the formula \(R_{ht}\) = 1.888 \(R_{hs}\) \(-\) 0.3533. The determination coefficient \(R^{2}\) = 0.963 was used to verify the simulation accuracy.