This study investigates three-dimensional (3D) flow fields around a flapping wing with a span of 20 cm. Numerical simulations are performed by varying the simulation mesh density for a half-flapping-wing profile with wind tunnel domain for flapping stroke angles of 53° and 90°. Wind velocities ranging from 1 to 3 m/s, variation in flapping frequency of 14–15 Hz, and corresponding lift characteristics are obtained. Comparative evaluation of numerical and experimental lift force data reveals the translational and rotational lift phenomena of Dickinson’s mechanisms. The stream line that flows over the 3D wing profile is found to be in good agreement with the existing smoke trace experimental data. The motions of a flapping wing obtained through 3D stereo photography and COMSOL Multiphysics simulation are compared and the aerodynamic characteristics are exploited. The streamwise and spanwise 3D velocity fields with intercepting planes at three chord sections are explored, and the reverse Kármán vortex sheet is observed. The comparison of the simulation and experimental results for a 3D flapping wing provides insight into the motion characteristics of a flapping wing and flapping wing aerodynamic analysis of micro air vehicles.
Journal of Marine Science and Technology 26(3), p.297-308