Analysis of Two-Dimensional Incompressible Flow Past Airfoils Using Unsteady Navier-Stokes Equations

The flow over streamlined lifting airfoils has been a subject of considerable interest to fluid dynamicists, and to date, significant progress has been made towards the design of airfoils, wings, etc., by drawing together resources from experimental, numerical, analytical, and empirical studies. The detailed flow structure of airfoils and wings near maximum lift in low-to-high Reynolds-number (Re) flows still remains unresolved. The increasing interest in these flows stems from the desire for better control in civilian aircraft, and for high maneuvering capability in high-performance military aircraft. The improved performance can be realized from the potential of increasing maximum lift and simultaneously reducing drag under this condition. For some combination of flow parameters, the flow field around an airfoil experiences significant separation, which degrades its performance and leads to stall. The nature of the stall may be characterized by various phenomena such as separation, unsteadiness, transition, and turbulence. The present study is directed towards accurately simulating this flow field and providing further insight into this class of flows. Other important fluid-dynamics applications involving unsteady flows include blade rows in turbomachinery, marine propellers, helicopter rotor blades, and bluff bodies such as buildings, towers, underwater cables, etc., in cross flows. For this class of bluffy-body flows, understanding the vortex-shedding characteristics is very significant. The simulation technique presented here can also provide guidelines for analyzing some of these flow fields.