# Drift Potential Characteristics of a Flat Fan Nozzle: A Numerical and Experimental Study
## 2 Model Construction and Numerical Simulation
### Numerical Results
#### 2.3.2 Simulated Droplet Parameters  
To study the particle size characteristics of the discrete-phase, several discrete-phase particles were ejected from the nozzle for 0.005 s when ejecting 0.01 s. In the simulations, the actual droplet size distribution of particles (those passing through a particle size laser beam during the actual test) was approximated by the statistical size distribution of the beam particles released for a very short duration. The ground, with a deposition height of 0.6 m, was computed by a Fluent discrete-phase particle-statistics function, and then the droplet drift characteristics were calculated. The drift of the discrete-phase under different crosswind conditions was obtained through mass statistics of the discrete-phase deposited in rectangular blocks at different unit distances on the bottom. The particle size results obtained by the numerical simulation of the discrete-phase under the influence of different lateral wind speeds are listed in Table 1.  
Table 1 summarizes the particle parameters of the discrete-phases under seven equally spaced lateral wind speeds. \(D_{\mathrm{v0.5}}\) gradually increases with the increase in lateral wind speed. \(D_{\mathrm{v0.1}}\), \(D_{\mathrm{v0.9}}\), V100, and the droplet spectrum width oscillate within certain ranges. As illustrated in Figure 2, when the wind speed at the air inlet is 0, the discrete-phase droplets of the nozzle are distributed on a fan-shaped surface with an injection angle of 120\({}^{\circ}\) and diffuse outward at a diffusion angle of 6\({}^{\circ}\). Most discrete-phase particles were within the ellipse obtained by Equations (1)-(3), with the exception of a few disordered particles. The accurate deposition ratio \(R_{a}\) and horizontal drift rate \(R_{h}\) in the elliptical plane are depicted in Figure 3.  
In Figure 3, the color scale represents the discrete-phase deposition mass concentration at different positions on the bottom of the wind tunnel. The color gradient from blue to red represents the increase in the mass concentration of discrete-phase deposition from 0 kg/m\({}^{3}\) to 2 kg/m\({}^{3}\). As indicated in Figure 3, in the absence of lateral wind, the simulated cloud map of the deposition mass concentration for the discrete-phase on the bottom surface is highly consistent with the area calculated by Equations (1)-(3). Because the intermediate region below the nozzle is directly sprayed and the middle of the nozzle is wide, a large amount of discrete-phase can be deposited. The deposition amount on the bottom gradually decreases from the center to both sides due to their narrow dimensions. In addition, the movement speed of spray droplets in the \(z\)-direction decreased as the spraying time increased. Overall, within the spraying range, the spray amount first increased and then decreased along the \(z\)-direction. Because the spray amplitude of the nozzle was greater than 2 m, the spray droplets on both sides collided with the sidewall and rebounded to the bottom, resulting in a high amount of droplet deposition. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Horizontal** & & & & & & & \\
**Wind** & **0** & **1** & **2** & **3** & **4** & **5** & **6** \\
**Speed/m/s** & & & & & & & \\ \hline \(D\mathrm{v0.1}\)/\(\,\mathrm{\SIUnitSymbolMicro m}\) & 100.00 & 105.78 & 126.11 & 125.97 & 121.46 & 127.34 & 119.01 \\ \(D\mathrm{v0.5}\)/\(\,\mathrm{\SIUnitSymbolMicro m}\) & 218.49 & 229.05 & 225.51 & 227.10 & 235.25 & 238.84 & 241.78 \\ \(D\mathrm{v0.9}\)/\(\,\mathrm{\SIUnitSymbolMicro m}\) & 351.38 & 339.51 & 349.15 & 333.13 & 358.99 & 347.56 & 346.98 \\ V100/\(\,\mathrm{\char 37}\) & 10.21\(\,\mathrm{\char 37}\) & 5.70\(\,\mathrm{\char 37}\) & 3.96\(\,\mathrm{\char 37}\) & 4.04\(\,\mathrm{\char 37}\) & 4.30\(\,\mathrm{\char 37}\) & 4.68\(\,\mathrm{\char 37}\) & 5.36\(\,\mathrm{\char 37}\) \\ Droplet & & & & & & & \\ Spectrum & 1.15 & 1.02 & 0.92 & 0.91 & 1.01 & 0.92 & 1.01 \\ Width & & & & & & & \\ \hline \hline \end{tabular}
\end{table}