Capturing wake capture: a 2D numerical investigation into wing-wake interaction aerodynamics.

Area of Science:

• Fluid dynamics
• Aerodynamics
• Bio-inspired engineering

Background:

• Insect flight involves complex wing kinematics and aerodynamics.
• Hovering insects generate wakes that influence subsequent wing strokes, impacting aerodynamic performance.
• Understanding the 'wake capture' mechanism is crucial for bio-inspired flight technologies.

Purpose of the Study:

• To numerically investigate the aerodynamic effects of 2D wings interacting with their own wake.
• To analyze the influence of different kinematic parameters, such as stroke distance and pitching rotation, on wake interaction.
• To elucidate the underlying physics of wake capture in insect flight at low Reynolds numbers.

Main Methods:

• Numerical simulation of 2D wing motion at Reynolds numbers 10^2 and 10^3.
• Employing a kinematic model with translational strokes followed by a stop, with varying stroke distances (1.5-6.0 chord lengths).
• Investigating pitching rotations at stroke end (135°, 90°, 45°) to simulate insect wing movements.

Main Results:

• Wake interaction effects depend on leading-edge vortex (LEV) attachment states (detached/attached).
• Vortex suction and jet flow impingement mechanisms can yield positive or negative lift.
• Pitching rotation induces a trailing-edge vortex (RTEV), significantly altering wake interaction lift based on LEV state and pitching angle.

Conclusions:

• Wing-wake interaction is a critical factor in insect flight aerodynamics.
• LEV attachment and pitching strategy determine the beneficial or detrimental effects of wake capture.
• The findings provide insights for designing efficient micro-air vehicles inspired by insect flight.