Study of techniques for obtaining continuous models from 2D discrete reduced-order state-space CFD models

Ann L. Gaitonde*, D. P. Jones

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

4 Citations (Scopus)

Abstract

The application of unsteady computational fluid dynamics (CFD) codes to aeroelastic calculations leads to a large number of degrees of freedom making them computationally expensive. Reduced-order models (ROMs) have therefore been developed; an ROM is a system of equations which is able to reproduce the solutions of the full set of equations with reasonable accuracy, but which is of lower order. ROMs have been the focus of research in various engineering situations, but it is only relatively recently that such techniques have begun to be introduced into CFD. In order for the reduced systems to be generally applicable to aeroelastic calculations, it is necessary to have continuous time models that can be put into discrete form for different time steps. While some engineering reduction schemes can produce time-continuous models directly, the majority of methods reported in CFD initially produce discrete time or discrete frequency models. Such models are restricted in their applicability and in order to overcome this situation, a continuous time ROM must be extracted from the discrete time system. This process can most simply be achieved by inverting the transformation from continuous to discrete time that was initially used to discretize the CFD scheme. However an alternative method reported in literature is based on continuous time sampling, even when this is not used for the initial discretization of the CFD code. This paper focuses on one particular method for ROM generation, eigensystem realization algorithm (ERA), that has been used in the CFD field. This is implemented to produce a discrete time ROM from a standard CFD code, that can be used to investigate methods for obtaining continuous ROMs and the limitations of the resulting models.
Translated title of the contributionStudy of techniques for obtaining continuous models from 2D discrete reduced-order state-space CFD models
Original languageEnglish
Pages (from-to)1247 - 1275
Number of pages19
JournalInternational Journal for Numerical Methods in Fluids
Volume52
Issue number11
DOIs
Publication statusPublished - 20 Dec 2006

Bibliographical note

Publisher: Wiley

Keywords

  • ERA
  • Reduced order
  • Unsteady CFD

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