Numerical Investigation of Flow Dynamics in Gliding Snake-Like Models: Vortex Structures and Aerodynamic Performance*

This work employs a sharp interface immersed-boundary-based incompressible Navier-Stokes flow solver to study the flow dynamics of a snake-like model exhibiting periodic horizontal undulation during steady gliding. Detailed vortex dynamics analysis examines vortex structures near the snake body, revealing the formation of oblique-shaped leading-edge vortices (LEV) and trailing-edge vortices (TEV) tubes due to the span-wise velocity. During the undulating period, a secondary LEV is generated at the anterior body, resulting in a 30% increase in lift generation over the body. The angle of attack (AOA) study demonstrates that the undulating body produces the highest average lift at AOA=45°, with a delayed-stall phenomenon compared to the 2D flying snake cross-section study. Moreover, LEV strength and lift enhancement are observed as the Reynolds number (Re) increases. Additionally, undulating frequency (f) changes influence LEV formation and its strength, significantly impacting the snake's aerodynamic performance. This study brings new knowledge on the role of undulatory motion in flying snake gliding, deepens our understanding of lift generation mechanisms, and offers potential guidance for future designs of aerial gliding aircraft.