Low Mach Number, Low Reynolds Number Airfoil Non-steady Flow Numerical Simulation,

This paper starts from the motion of insects. We simplify the motion of insects into a kind of combination of plunging and pitching, and then use N-S equation to solve the flow around the airfoil. In every time-marching step, we must regenerate the mesh. In order to improve the efficiency of the mesh generation, we employ the transfinite interpolation method. In low speed flow (M<0.05), the low mach will aggravate the difference between eigenvalues of the system and make the convergence sharply difficult. As for this, we use the preconditioning method to remove it. On solving the equation, we utilize the finite volume method. Runge-Kutta method with the dual time marching was also used here. In order to accelerate the convergence speed, we employ the local time step, and implicit residual smoothing methods. Finally, we use this method to get the steady solution of the flow around NACA0012 and NACA4412 airfoil at very low speed and some basic unsteady solution.