Large-eddy-simulation-informed resolvent-based estimation of turbulent pipe flow

Abstract

© 2023 American Physical Society.A resolvent-based methodology is employed to obtain spatiotemporal estimates of turbulent pipe flow from probe measurements of wall shear-stress fluctuations. Direct numerical simulations (DNSs) and large-eddy simulations (LESs) of turbulent pipe flow at a friction Reynolds number of 550 are used as databases. We consider a DNS database as the true spatiotemporal flow field, from which wall shear-stress fluctuations are extracted and considered as measurements. A resolvent-based estimator is built following our earlier work [Amaral, J. Fluid Mech. 927, A17 (2021)0022-112010.1017/jfm.2021.764], requiring a model for the nonlinear (or forcing) terms of the Navier-Stokes equations system, which are obtained from another DNS database, as in our earlier work, and from a series of computationally cheaper LES databases with coarser grids; the underlying idea is that LESs may provide accurate statistics of nonlinear terms related to large-scale structures at a low computational cost. Comparisons between the DNS and the estimates indicate that sufficiently accurate results can be achieved with estimators built with statistics from LESs with an order of magnitude fewer grid points than the DNSs, with estimates closely matching the reference DNS results up to the buffer layer and reasonable agreement up to the beginning of the log layer.