Numerical simulation of three-dimensional instability of flow past a short cylinder

The two-dimensional flow around an infinitely long circular cylinder becomes three-dimensional starting with Reynolds numbers $\operatorname{Re}\approx 190$. The corresponding instability mode is called mode A. When $\operatorname{Re}\approx260$, structures with smaller cross-scale are formed in the wake as a result of a secondary three-dimensional instability (mode B). In this work, we consider the transition to three-dimensionality for a short cylinder bounded by planes. The length of the cylinder is chosen to eliminate the unstable perturbations of mode A. There have been found two modes of instability, which are analogues of modes A and B but modified under the influence of the limiting end planes. Numerical solutions of problems of three-dimensional flow are based on the Navier–Stokes equations.