![]() Due to the limited volume and payload capabilities of small-scale vehicles, traditional flow control devices’ size, complexity, and weight penalties are prohibitive 1, 6, 7, 10, 11. Second, bioinspired flow control techniques are more suitable for small-scale uncrewed vehicles than traditional approaches developed for large-scale and high-speed operations. First, these techniques provide new insight into biological locomotion and uncover the physics that enable these organisms to be adaptable and efficient across multiple flight conditions. Understanding biological and bioinspired flow control techniques help in two crucial ways. More recently, studies have focused on bioinspired and biological flow control techniques 9. Most of these studies focus on engineered flow control devices, large-scale aircraft, and fully developed turbulent conditions (Reynolds number (Re) ≥ 10 6) 8. There have been extensive studies and reviews on flow control techniques and devices 3, 4, 6, 7. Examples of local flow control devices include synthetic jet actuators or roughness strips, while wing sweep and camber morphing systems would be considered global flow control devices. In contrast, global flow control devices usually affect the flow over the entire wing or lifting surface. Local flow control devices introduce localized changes to the flow structures at a particular area of the lifting surface. Another classification is related to the area affected by the flow control device, namely local versus global flow control (Fig. On the other hand, active flow control devices require actuation and power to affect the flow 5. Passive flow control requires no actuation nor energy expenditure, making it less complex and more affordable however, it cannot always provide enough control authority or adaptability, especially in complex applications 3, 4. Multiple classifications exist for flow control devices one of the most common ways is to classify flow control techniques as active or passive based on their energy expenditure. Such mechanisms often lead to drag reduction, lift enhancements, or noise suppression and can be implemented through flow control devices such as flaps, slats, or synthetic jets, to mention a few. Flow control mechanisims include postponing boundary layer separation, delaying or advancing laminar-turbulent transition, and altering vortical structures and dynamics (Fig. Flow control is defined as attempting to favorably modify a flow field’s characteristics compared to how the flow would have developed naturally along the surface 1, 2. This agility and maneuverability are possible because of the ability of these biological systems to alter the flow around their lifting and thrusting surfaces, using what is referred to as flow control. The same animal, for example, a flyer, can repeatedly take off, hover, glide, flap, and perch in different environmental conditions, such as during gusts and thermals or closer to the ground or the water surface. Natural flyers and swimmers operate under various conditions.
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