Application of an Immersed Boundary Method to Three-dimensional Floquet Stability Analysis

초록

An immersed boundary method(IBM, Kim et al.(2001)) for simulating flows over complex geometries is applied to computation of three-dimensional Floquet instability modes of a periodic wake. Floquet stability analysis is employed to extract different modes of three-dimensional instability. To verify the present method, a fully-resolved Floquet stability calculation for flow past a circular cylinder is presented. There are two different instability modes with long (mode A) and short (mode B) spanwise wavelengths for the periodic wake of a circular cylinder. The critical Reynolds numbers and the most unstable spanwise wavelengths of modes A and B are computed using the present method, and compared with other authors' results currently available.