# Numerical Study of Aircraft Wake Vortex Evolution under the Influence of Vertical Winds
## 4 Conclusions  
In this paper, we conducted a study using numerical simulations to investigate the impact of different intensities and directions of vertical wind on aircraft wake vortex structures and vortex parameters, which have provided new insights into the dynamics of aircraft wake vortices under the influence of vertical wind. Different wind intensities and directions can significantly affect vortex structure and decay rates. Negative vertical wind impacts the vortex minimally, maintaining a structure akin to calm conditions, while positive wind alters the vortex significantly. These findings are crucial for devising strategies to  
Figure 19: Horizontal position distribution of the vortex core at different wind speeds. Figure 20: Vertical position distribution of the vortex core at different wind speeds. mitigate wake turbulence hazards, especially during the critical phases of flight near the ground, ultimately enhancing aircraft safety and operational efficiency. Specific conclusions were drawn:  
1. Negative vertical wind has minimal impact on the wake vortex structure and remains similar to calm wind conditions. However, favorable vertical wind disrupts the internal balance of the wake vortex and the turbulence within the airflow, leading to distortion or stretching of the vortex structure and causing an overall \"flattening\" of its shape. 2. Vortex intensity rapidly decreases during the initial formation of the vortex and then gradually diminishes. Vertical wind reduces the initial vortex intensity and increases the rate of vortex intensity decay. Under wind conditions with the same absolute wind speed, convective effects result in higher vortex intensity for negative wind speeds than positive wind speeds, leading to longer-lasting wake vortices. Moreover, the rate of vortex intensity decay is not linearly correlated with wind speed, as vortex intensity decays faster at wind speeds of 1-3 m/s compared to 4 m/s. 3. With high vertical wind speeds, the vortex core is influenced by wind speed gradients and rotational rate gradients, which enhance the instability of the primary vortex core. This causes irregular movements and interactions within the vortex core, forming secondary vortex structures. Simultaneously, the horizontal position of the primary vortex core rapidly contracts inwards. 4. Under low-wind-speed conditions, the vortex core briefly contracts inwards before stabilizing into oscillations. Vertical wind inhibits the reduction in vortex core spacing, resulting in a slower reduction rate compared to calm wind conditions. This leads to a larger wake turbulence hazard zone. Under high wind speed conditions, the vortex core initially contracts rapidly inwards before stabilizing slowly. The vertical movement of the vortex core is in the direction of the wind. The greater the wind speed, the greater the displacement. Notably, for wind speeds of 1 m/s and 2 m/s, the effect of vortex core descent is most significant. As wind speed increases to a certain threshold, the impact of core decline remains relatively constant due to the influence of airflow inertia effects. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app14010086/s1](https://www.mdpi.com/article/10.3390/app14010086/s1)]([https://www.mdpi.com/article/10.3390/app14010086/s1](https://www.mdpi.com/article/10.3390/app14010086/s1)). [PERSON] and [PERSON] established the flow field model, divided the grid, and performed the grid independence test. [PERSON] debugged the numerical simulation conditions and performed numerical simulation. [PERSON] and [PERSON] processed the data of the rear flow field and analyzed the results. [PERSON] provided the literature review and contributed to the writing of the manuscript. [PERSON] and [PERSON] reviewed the paper and supervised the work. All authors have read and agreed to the published version of the manuscript. This research was supported by the National Key R&D Program of China (No.