Nudgingbased data assimilation of the turbulent flow around a square cylinder
Abstract
We investigate the prediction of the turbulent flow around a canonical square cylinder at Re= 22000 solving the unsteady Reynoldsaveraged NavierStokes (URANS) equations. The limitations of URANS modelling are overcome through the application of a data assimilation technique involving a feedback control term, allowing to drive the URANS predictions towards reference data. Using regularlyspaced temporallyresolved reference data that are extracted from DNS, we assess the abilities of the data assimilation methodology in improving the unsteady URANS predictions. While improving the lowfrequency oscillations of the wake flow, we also demonstrate the ability to recover the highfrequency dynamics of KelvinHelmholtz instabilities. The influence of spatial resolution of reference data is systematically investigated. The data resolution which is required to improve the prediction of flow structures of interest is related to their wavelength. Using a spacing of the order of one cylinder length between data points, we already observe synchronisation of the lowfrequency vortex shedding that leads to a significant decrease in temporal and spectral errors as computed by spectral proper orthogonal decomposition. Furthermore,improved accuracy in terms of mean flow prediction of URANS is achieved. Using spacing of the order of the wavelength of the KelvinHelmholtz vortices, we even recover those shear layer structures which are absent in the baseline simulation.
 Publication:

arXiv eprints
 Pub Date:
 October 2021
 arXiv:
 arXiv:2110.10651
 Bibcode:
 2021arXiv211010651Z
 Keywords:

 Physics  Fluid Dynamics