In this paper, a thorough 2D unsteady computational fluid dynamic analysis was performed on pitching airfoil to properly comprehend the stall and aerodynamic forces. The software ANSYS Fluent used solve Reynolds-averaged Navier–Stokes equations. Low Reynolds number flows were modeled using k-ω shear stress transport turbulence model. Aerodynamic forces, flow structures, separation delay angles ...

Gliding is an efficient form of travel found in every major group of terrestrial vertebrates. Gliding is often modelled in equilibrium, where aerodynamic forces exactly balance body weight resulting in constant velocity. Although the equilibrium model is relevant for long-distance gliding, such as soaring by birds, it may not be realistic for shorter distances between trees. To understand the a...

The paper describes a formulation for aeroelastic analysis of aircraft with high-aspect-ratio wings. The analysis is a combination of a geometrically-exact mixed formulation for dynamics of moving beams and finite-state unsteady aerodynamics with the ability to model dynamic stall. The analysis also takes into account gravitational forces, propulsive forces and rigidbody dynamics. The code has ...

All animals flap their wings in powered flight to provide both lift and thrust, yet few human-engineered designs do so. When combined with flexible wing surfaces, the resulting unsteady fluid flows and interactions in flapping flight can be complex to describe, understand, and model. Here, a simple modified actuator disk is used in a quasi-steady description of the net aerodynamic lift forces o...

A flying insect generates aerodynamic forces through the active manipulation of the wing and the “passive” properties of deformability and wing shape. To investigate these “passive” properties, the flexural stiffness of dried forewings belonging to 10 butterfly species was compared to the butterflies’ gross morphological parameters to determine allometric relationships. The results show that fl...

This paper describes a new multidisciplinary computational study undertaken to model the flight trajectories and the free-flight aerodynamics of both a finned projectile at supersonic velocities and a spinning projectile at subsonic speeds with and without aerodynamic flow-control. Actual flight trajectories are computed using an advanced coupled computational fluid dynamics (CFD)/rigid body dy...

The need to further exploit offshore wind resources in deeper waters has led to a re-emerging interest in vertical axis wind turbines (VAWTs) for floating foundation applications. However, there has been little effort to systematically compare VAWTs to the more conventional horizontal axis wind turbine (HAWT). This article initiates this comparison based on prime principles, focusing on the tur...

Wing pitch reversal, the rapid change of angle of attack near stroke transition, represents a difference between hovering with flapping wings and with a continuously rotating blade (e.g. helicopter flight). Although insects have the musculature to control the wing pitch during flight, we show here that aerodynamic and wing inertia forces are sufficient to pitch the wing without the aid of the m...

Turning in flight requires reorientation of force, which birds, bats and insects accomplish either by shifting body position and total force in concert or by using left-right asymmetries in wingbeat kinematics. Although both mechanisms have been observed in multiple species, it is currently unknown how each is used to control changes in trajectory. We addressed this problem by measuring body an...

Insects are highly maneuverable fliers. Naturally, engineers have focused much of their efforts on understanding the role of insect wing design and actuation for maneuvering and control of bio-inspired micro air vehicles. However, many insects exhibit strong visually mediated abdominal reflexes. The hawkmoth, Manduca sexta, has a particularly large abdomen, and recent evidence suggests that the...