Modal decomposition of the pressure field on a bridge deck under vortex shedding using POD, DMD and ERA with correlation functions as Markov parameters

Abstract

A pressure field on a stationary bridge section with a clear signature from vortex shedding is obtained from a numerical simulation. The pressure field is subjected to modal decomposition using the snapshot prober orthogonal decomposition method (POD), the exact dynamic mode decomposition method (DMD) and a novel application of the eigenvalue realization algorithm (ERA) where the correlation functions of the pressure field is used as Markov parameters. All three methods are able to identify spatial mode shapes of the surface pressure field due to vortex shedding. The Strouhal number is estimated using dynamic mode decomposition and the eigenvalue realization algorithm where the latter is the most accurate and precise method. Finally, the ERA is applied to estimate Strouhal numbers and vortex shedding pressure mode shapes under different flow conditions in wind tunnel and full-scale testing of the Gjemnessund bridge in Norway.