## 3 Results and Discussion

Table 2: Parameters of rotating-fluid domains: rotating-axis origin and rotational velocity. flows, manifests in the airflow produced by the UAVs [22]. This study introduces a new phenomenon named the \"Near-UAV Phenomenon\" resulting from the investigation of close UAV effects. Figure 4: Vertical and horizontal data lines of swarm UAVs. Figure 5: Velocity contours: (**a**) rear plane; (**b**) midplane of the UAVs; (**c**) front plane. Velocity contours obtained over vertical planes in Figure 6 are presented comparatively, while the corresponding locations of these planes are indicated in Figure 4. The distances of these planes, relative to the propeller planes of the UAVs positioned above and below are specified as follows; Y560 and Y485 60 cm, Y580 and Y505 40 cm, Y600 and Y525 20 cm, and Y535 and Y610 10 cm under. The velocity value ranges in these contours are 1 to 22 m/s. When examining the Y600 and Y525 vertical planes, it is clearly observed that the velocity distribution increased after the vehicles positioned below. The formation of vortices was observed between the UAVs at Y610, Y600, and Y80 vertical planes. In the Y560 contour, the outward flow generated by the propellers of the UAVs positioned above was affected by the flow generated by the UAVs positioned below, resulting in distribution up to Y505 while passing near the vehicles. This distribution is visually represented with streamlines in Figure 7.  
The streamlines generated by the UAVs are illustrated in Figure 7, where Figure 7a shows the top view and Figure 7b shows the front view. By following the paths of the streamlines and the resulting trajectories, the flows around the vehicles were determined, and the velocities along the streamlines were also shown. The turbulence occurring between the UAVs was visualized. Additionally, it was observed that the flow generated by the outer propellers of the UAVs positioned above passed through between the vehicles. The velocity values are presented as plots in Figure 8, representing the front propellers. The horizontal lines Y600 and Y525 are located 20 cm below the rotation centers of the UAV propellers. In these regions, velocities measured from the tip of the propellers are approximately 18-19 m/s, and the velocity distributions are high due to the proximity to the propellers. Figure 6: Velocity contours in vertical planes. The Y580 to Y505 lines are 40 cm below the rotation centers. The velocities under the propeller tips are approximately 14 m/s in the UAVs positioned above, while velocities are approximately 15 m/s in the vehicles positioned below. The distribution of velocities  
Figure 8: Velocity plots of front(F) propeller taken from horizontal lines. Figure 7: Streamline velocity: (**a**) top view; (**b**) front view. increases towards the propeller tips. Additionally, when examining the airflow between adjacent vehicles horizontally, velocity distributions are increased. The Y560 to Y485 lines are located 60 cm below the centers of rotation. The velocity distribution at Y485 is increased compared to Y560 due to the downward flow. While the speed is 12 m/s at Y560, it has increased to 14 m per second at Y485. It is clearly seen that the airflow produced by the upper UAVs affects the lower UAVs with the horizontal lines. Velocity distributions on vertical data lines are shown in Figure 9. Data were collected along vertical lines ranging from X220 to X345. The values X220, X245, X320, and X345 represent the vertical lines taken from the propeller axes, while X270, X282.5 (midpoint), and X295 are used to determine the vertical lines between the UAVs. The velocity plot obtained along these vertical lines is illustrated in Figure 9. The values of Y at 620 cm and 545 cm correspond to the rotating-axis origin of the propellers. Examining the graph of data obtained from vertical lines indicates that the velocity under the upper vehicles at Y = 600 cm reaches approximately 19 m/s on the X220 and X345 lines, while it is up to about 14 m/s on the X245 and X320 lines.