FN Archimer Export Format PT J TI Quantifying Truncation-Related Uncertainties in Unsteady Fluid Dynamics Reduced Order Models BT AF Resseguier, Valentin Picard, Agustin M. Memin, Etienne Chapron, Bertrand AS 1:1;2:1;3:2;4:3; FF 1:;2:;3:;4:PDG-ODE-LOPS-SIAM; C1 Lab, SCALIAN DS, Rennes, France Fluminance team, Inria, Rennes, France LOPS, Ifremer, Plouzané, France C2 SCALIAN, FRANCE INRIA, FRANCE IFREMER, FRANCE SI BREST SE PDG-ODE-LOPS-SIAM UM LOPS IN WOS Ifremer UMR copubli-france IF 2.089 TC 5 UR https://archimer.ifremer.fr/doc/00724/83581/88589.pdf LA English DT Article DE ;fluid dynamics;reduced order model;uncertainty quantification;stochastic closure;proper orthog-onal decomposition AB In this paper, we present a new method to quantify the uncertainty introduced by the drastic dimensionality reduction commonly practiced in the field of computational fluid dynamics, the ultimate goal being to simulate accurate priors for real-time data assimilation. Our key ingredient is a stochastic Navier--Stokes closure mechanism that arises by assuming random unresolved flow components. This decomposition is carried out through Galerkin projection with a proper orthogonal decomposition (POD-Galerkin) basis. The residual velocity fields, model structure, and evolution of coefficients of the reduced order's solutions are used to compute the resulting multiplicative and additive noise's correlations. The low computational cost of these consistent correlation estimators makes them applicable to the study of complex fluid flows. This stochastic POD-reduced order model (POD-ROM) is applied to 2-dimensional and 3-dimensional direct numerical simulations of wake flows at Reynolds 100 and 300, respectively, with uncertainty quantification and forecasting outside the learning interval being the main focus. The proposed stochastic POD-ROM approach is shown to stabilize the unstable temporal coefficients and to maintain their variability under control, while exhibiting an impressively accurate predictive capability. PY 2021 SO Siam-asa Journal On Uncertainty Quantification SN 2166-2525 PU Society for Industrial & Applied Mathematics (SIAM) VL 9 IS 3 UT 000717476500008 BP 1152 EP 1183 DI 10.1137/19M1354819 ID 83581 ER EF