Ground-induced lift enhancement in a tandem of symmetric flapping wings: Lattice Boltzmann-immersed boundary simulations

The behavior of a tandem of symmetric flapping wings immersed in a quiescent viscous fluid is numerically dissected. The attention focuses on the effect on the flight performance of a solid surface which idealizes the presence of the ground. A wide numerical campaign is carried out. The author demonstrates that the presence of a solid surface can drastically modify the lift force, thus giving a remarkable advantage for the vertical take-off. Therefore, a proper governing parameter is proposed, which accounts for the ratio between the initial gap from the solid surface and the length of the wing.