UC San Diego

The two-dimensional flow over the cylinder is simulated using Ansys Fluent and analyzed using spectral proper orthogonal decomposition (SPOD). The SPOD eigenvalues and eigenvectors are used to get the Strouhal numbers ($St$) and eigenmodes. Circular and square cylinder flows are analyzed at three different Reynolds numbers ($Re$) of 60, 100, and 150. Elliptical cylinder flows are analyzed at $Re$ = 150 with different aspect ratios of 0.25, 0.5, and 4. The $St$ of circular cylinder flow is close to literature data and the ones of square and elliptical cylinder flow have greater differences from literature data. The $St$ is larger at larger $Re$. The modes show symmetric structures at $St$ and 3$St$ and anti-symmetric structures at 2$St$ for all cases. Elliptical cylinder cases are simulated again in a larger domain. The case with AR = 0.25 shows a secondary vortex street structure at the far wake. A secondary frequency at 0.07781 is observed and the modes at that frequency have Karman vortex street structures at the far wake.