| Abstract: | The two-winged insect hovering flight is investigated numerically
using the lattice Boltzmann method (LBM). A virtual model of two
elliptic foils with flapping motion is used to study the aerodynamic
performance of the insect hovering flight with and without the
effect of ground surface. Systematic studies have been carried out
by changing some parameters of the wing kinematics, including the
stroke amplitude, attack angle, and the Reynolds number for the
insect hovering flight without ground effect, as well as the
distance between the flapping foils and the ground surface when the
ground effect is considered. The influence of the wing kinematic
parameters and the effect of the ground surface on the unsteady
forces and vortical structures are analyzed. The unsteady forces
acting on the flapping foils are verified to be closely associated
with the time evolution of the vortex structures, foil translational
and rotational accelerations, and interaction between the flapping
foils and the existed vortical flow. Typical unsteady mechanisms of
lift production are identified by examining the vortical structures
around the flapping foils. The results obtained in this study
provide some physical insight into the understanding of the
aerodynamics and flow structures for the insect hovering flight. |
