Unsteady aerodynamics of flapping wing of a bird

The unsteady flow behavior and time-dependent aerodynamic characteristics of the flapping motion of a bird's wing were investigated using a computational method. during flapping,aerodynamic interactions between bird wing surfaces and surrounding flow may occur,generating local time-dependent flow changes in the flow field and aerodynamic load of birds. to study the effect of flapping speed on unsteady aerodynamic load,two kinds of computational simulations were carried out,namely a quasi-steady and an unsteady simulation. to mimic the movement of the down-stroke and the upstroke of a bird,the flapping path accorded to a sinus function,with the wing attitude changing in dihedral angle and time. the computations of time-dependent viscous flow were based on the solution of the reynolds averaged navier-stokes equations by applying the k-ε turbulence model. in addition,the discretization for the computational domain around the model used multi-block structured grid to provide more accuracy in capturing viscous flow,especially in the vicinity of the wing and body surfaces,to obtain a proper wing-body geometry model. for this research,the seagull bird was chosen,which has high aspect ratio wings with pointed wing-tips and a high camber wing section. the results include mesh movement,velocity contours as well as aerodynamic coefficients of the flapping motion of the bird at various flapping frequencies. © 2013 published by itb journal publisher.