in this paper, lift and drag coefficients were numerically investigated using numeca software in a set of 4-digit naca airfoils. two metamodels based on the evolved group method of data handling (gmdh) type neural networks were then obtained for modeling both lift coefficient (cl) and drag coefficient (cd) with respect to the geometrical design parameters. after using such obtained polynomial n...

Bird flight is an area of significant interest due to the utilization and control of unsteady aerodynamic effects via flapping. Although modern aerodynamics were originally inspired by bird flight, contemporary computational and experimental work associated with flapping flight focuses on insect flight. The purpose of the present paper is to improve the understanding of avian flight by investig...

CL, CD, CD0 = lift coefficient, drag coefficient, and drag coefficient with zero lift DSi = dynamic soaring number sample E, Emin = aircraft total energy and minimum sustainable total energy, J g = gravity acceleration, m∕s h, hmin = altitude and safety altitude, m K = drag-polar-induced drag gain k1, k2, k3 = necessary and sufficient conditions inequality parameters L, D = lift and drag forces...

Studies of insect flight have focused on aerodynamic lift, both in quasi-steady and unsteady regimes. This is partly influenced by the choice of hovering motions along a horizontal stroke plane, where aerodynamic drag makes no contribution to the vertical force. In contrast, some of the best hoverers--dragonflies and hoverflies--employ inclined stroke planes, where the drag in the down- and ups...

nowadays, we live in a world which quality, speed, accuracy and cost are the most important parameters in parts' design and manufacturing. due to the complexity of part manufacturing, traditional and nontraditional manufacturing techniques are used. aerodynamic tests usually requires one or several models for testing in wind tunnels and these models typically have particular complexities in whi...

In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: Abstract A transversely oscillating cylinder in a uniform flow is modeled to investigate frequency effects of flow-induced w...

The objective of this paper is to study the effect of an unsteady moving heat source on the aerodynamic performance of an NACA 0012 airfoil section, with particular focus on the lift and drag coefficients. The compressible Navier–Stokes equations are solved using a finite volume method as well as Spalart-Allmaras Model for turbulence simulation. The heat source periodically moves over the lower...

We present a new mathematical theory explaning the mircale of flight which is fundamentally different from the existing theory by Kutta-ZhukovskyPrandtl formed 100 year ago. The new theory is based a new resolution of d’Alembert’s paradox showing that slightly viscous bluff body flow can be viewed as zero-drag/lift potential flow modified by a specific separation instability into turbulent flow...

Abstract It is known that plunging airfoil can produce both lift and thrust with certain combination of plunging amplitude and frequency. Motivated by our interest in micro air vehicles (MAVs), we utilize a NavierStokes equation solver to investigate the aerodynamics of a flapping airfoil. The roles of the plunging and pitching amplitude and frequency, and Strouhal number are studied. For a sym...