FLOW PATTERN ON THE SURFACE OF AIRFOIL WITH LOWER REYNOLDS NUMBER

In this paper aerodynamic performance of the NACA0012 airfoil in the incompressible flow with a lower Reynolds number (Re) is investigated numerically from the viewpoints of flow pattern and nonlinear dynamics. First, the characteristic-based split (CBS) finite element method is introduced for the approximation of the incompressible Navier-Stokes equations, and then the lid-driven cavity flow and flow around a circular cylinder are calculated for varification. Then, at Re=1000, flow fields around the NACA0012 airfoil at a series of angles of attack are simulated. With the increase of the attack angle, great change of the flow pattern appears. and the flow structures such as trailing edge vortex, separation bubble and shedding vortex are observed. Moreover it is found that the separation bubble plays an important role in the deterioration of the flow stability at higher attack angles, and the vortex shedding can be taken as the result of a Hopf bifurcation while the bifurcation parameter is the angle of attack.