Leveraging similarity in coherent structures to alleviate computational costs for high Reynolds number wake simulations

Coherent structures in a turbulent wake can be obtained using Spectral Proper Orthogonal Decomposition (SPOD). Structural similarity in dominant coherent structures that are identified by SPOD analysis is demonstrated between Re = 5 × 10³ and Re = 5 × 10⁴ cases of a disk wake. The dominant SPOD modes in streamwise-constant planes are similar in shape between the two Re values although there is more high-mode energy at the higher Re. Cross-stream plane data for Re = 5 ×10⁴ is reconstructed using the eigenmodes of Re = 5 × 10³ and numerically modifying their energy. The reconstructed data is used to initialize body-exclusive spatial simulation at Re = 5 × 10⁴ whose results are compared to those from body-inclusive simulations. This hybrid method of simulating a body-exclusive higher Reynolds number wake using body-inclusive simulation data from a lower Reynolds number leads to considerable savings in computational cost.