Numerical simulation of incompressible viscous flow past a heaving airfoil

Abstract

SUMMARYNumerical simulations of a heaving airfoil undergoing non-sinusoidal motions in an incompressible viscous ow is presented. In particular, asymmetric sinusoidal motions, constant heave rate oscillations, and sinusoidal motions with a quiescent gap, are considered. The wake patterns, thrust force coe cients, and propulsive e ciency at various values of non-dimensional heave velocity are computed. These have been compared with those of corresponding sinusoidal heaving motions of the airfoil. It is shown that for a given non-dimensional heave velocity and reduced frequency of oscillation, asymmetric sinusoidal motions give better thrust and propulsive e ciencies in comparison to pure harmonic motion. On the other hand, constant rate heave motion do not compare favourably with harmonic motion. A train of sinusoidal pulses separated by a quiescent gap compares favourably with a pure sinusoidal motion, but with the notable exception that the quiescent gap induces a discontinuity that induces large impulses to the wake pattern.

Study of mechanisms and factors that influence the formation of vortical wake of a heaving airfoil

“…The increasing velocity magnitude is in consistence with the fact that higher heaving frequency leads to higher input power from the airfoil, which provides more propulsive force. 9,12 Figure 7 also confirms the individual effect of reduced frequency and magnitude at a same V p that is the product of the these two factors. Each of the cases is represented by square, diamond, or circle symbols, and has the same V p values of 1.2, 1.08, and 0.96, respectively.…”

“…The Strouhal number, which is the product of reduced frequency and dimensionless heaving magnitude, is a considered a primary factor that influences the wake of a heaving airfoil. 6,7,9,10,12,15 The computational domain size selected for this study is 19.2 × 12.8, shown in Fig. 2.…”

“…Unsurprisingly, similar deflected wakes were found in flow with asymmetric sinusoidal airfoil motions. 9 However, unlike the cases with asymmetric airfoil motions, this phenomenon, with a pure symmetric sinusoidal heaving motion, only occurred at high Strouhal number that Lai and Platzer 10 defined as 2π f * h * /U ∞ , where f * and h * are the dimensional frequency and amplitude of the heaving motion, respectively. It was noted 6 that the direction of deflection did not change in numerical simulation, whereas in experiment, small disturbances might influence the flow and randomly change the direction of the deflected wake.…”

Conformal mapping and efficient boundary element method without boundary elements for fast vortex particle simulations

“…On one hand, we will consider panel methods with N panel = 160, the lowest number of panels used for vortex particle simulation [30], N panel = 400 used in Ramachandran [19], N panel = 600 for Walther [31], N panel = 800 and N panel = 1200.…”

Validation of Numerical Schemes and Turbulence Models Combinations for Transient Flow Around Airfoil

“…Voutsinas and Riziotis (1999) developed a viscous-inviscid interaction model for the simulation of dynamic stall on airfoils. Sarkar and Venkatraman (2005) used a discrete vortex method to simulate a heaving airfoil undergoing non-sinusoidal motions. The performance of numerical schemes and turbulence models has also been studied for wing sections of aircraft.…”