Basis Identification for Nonlinear Dynamical Syste

Authors: Rohit Deshmukh Zongxian Liang Jack J McNamara

Publish Date: 2016

Volume: , Issue: , Pages: 279-293

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Abstract

Basis identification is a critical step in the construction of accurate reduced order models using Galerkin projection This is particularly challenging in unsteady nonlinear flow fields due to the presence of multiscale phenomena that cannot be ignored and are not well captured using the ubiquitous Proper Orthogonal Decomposition This study focuses on this issue by exploring an approach known as sparse coding for the basis identification problem Compared to Proper Orthogonal Decomposition which seeks to truncate the basis spanning an observed data set into a small set of dominant modes sparse coding is used to select a compact basis that best spans the entire data set Thus the resulting bases are inherently multiscale enabling improved reduced order modeling of unsteady flow fields The approach is demonstrated for a canonical problem of an incompressible flow inside a 2D liddriven cavity Results indicate that Galerkin reduction of the governing equations using sparse modes yields significantly improved fluid predictionsThe authors gratefully acknowledge the support of ONR grant N000141410018 under the direction of Dr Judah Milgram an HPCMPO Frontier PETTT Project Grant under the direction of David Bartoe and an allocation of computing time from the Ohio Supercomputer Center The authors thank Dr Lionel Agostini Mr Kalyan Goparaju Mr S Unnikrishnan and Dr Datta Gaitonde Mechanical Aerospace Engineering The Ohio State University for providing technical guidance in the study of local flow dynamics

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