Aerodynamics of Low Reynolds Number Plunging Airfoil Under Gusty Environment

Unsteady Adjoint Approach for Design Optimization of Flapping Airfoils

“…Figure 2 presents the results of C d and C l from three different densities of C-type grid: coarse (257x49), intermediate (513x49), and fine (1025x193) and a fine (513x173) O-type grid. Besides the coarse C-type grid where the number of grid points along the airfoil direction is not enough to provide an accurate prediction of drag force, solutions of all other grids fall between those reported in [24]. The lift coefficients of all grids, including coarse grid, show high coincidence with each other.…”

“…We specify the flapping motion by imposing the velocity and displacement at grid points on the airfoil according to Eq. (24). Since there is no experimental data provided, we compared the current force measurement with the previously reported CFD results by Young [23] and Lian et al [24] The first case is at the reduced frequency, k, of 3.93, non-dimensional plunging amplitude, h 0 , of 0.0125 so that the resulted Strouhal number, St, is 0.03.…”

“…(24). Since there is no experimental data provided, we compared the current force measurement with the previously reported CFD results by Young [23] and Lian et al [24] The first case is at the reduced frequency, k, of 3.93, non-dimensional plunging amplitude, h 0 , of 0.0125 so that the resulted Strouhal number, St, is 0.03. Figure 2 presents the results of C d and C l from three different densities of C-type grid: coarse (257x49), intermediate (513x49), and fine (1025x193) and a fine (513x173) O-type grid.…”

“…It is reported that the contribution of viscous drag reaches about 70% of total drag [24] and the time-accuracy of the force measurement is highly sensitive to the grid distributions in these conditions. The flow is assumed laminar as the effects of Reynolds number did not appear significant for MAV flapping wings in previous work [1-7, 11-13, 20, 21].…”

Towards Computational Flapping Wing Aerodynamics of Realistic Configurations using Spectral Difference Method

“…Details of these other CFD results are shown in Figure 10 (b), excerpted from the Shyy etc. 18 The discrepancy between the SD2D result and the experiment result could be attributed to 3D effect. Indeed, the current 3D simulations of the Naca0012 airfoil show a dramatic improvement of the thrust prediction.…”