Numerical study of linearized unsteady stagnation flow
The stability of stagnation point flow has long been recognized as an important problem in aerodynamic analysis. Boundary layer disturbances located near the stagnation line can have a significant effect on the overall properties of an airfoil. One example of current interest is the analysis of unsteady multi-phase stagnation flows for application to problems involving aircraft icing. In this study, numerical methods which can be used to address the stability and non-parallel unsteady development of such stagnation point problems are investigated for linearized single phase aerodynamic flows using both two-dimensional and three-dimensional methods. A streamfunction-vorticity formulation is evaluated for two-dimensional linearized stagnation flows. In addition, a primitive variable formulation is developed for three-dimensional linearized stagnation flows. The two methods are tested for grid refinement, and results obtained using the three-dimensional method are compared with those from the two-dimensional method. As expected, it is found that three-dimensional disturbances decay at a faster rate than two-dimensional ones.