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Accelerating Unsteady CFD Simulations Using a Minimum Residual Based Nonlinear Reduced Order Modeling Approach

Ripepi, Matteo and Görtz, Stefan (2018) Accelerating Unsteady CFD Simulations Using a Minimum Residual Based Nonlinear Reduced Order Modeling Approach. In: AeroStruct: Enable and Learn How to Integrate Flexibility in Design Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 138. Springer International Publishing. pp. 237-255. ISBN 978-3-319-72020-3. ISSN 978-3-319-72019-7

Full text not available from this repository.

Official URL: https://doi.org/10.1007/978-3-319-72020-3_15

Abstract

Reduced-order modeling is evaluated as a means to speed up unsteady computational fluid dynamics (CFD) simulations while maintaining the desired Level of accuracy. In the reduced order modeling approach, proper orthogonal decomposition (POD) is applied to some computed response time history from a compressible, unsteady CFD solver to compute a set of orthogonal basis vectors. An approximate flow solution for the next time step is predicted by minimizing the unsteady flow solver residual in the space spanned by the POD basis. This is done by solving a non-linear least-squares problem. This approximate flow solution is then used to initialize the flowsolver at this time step, aiming to reduce the number of inner iterations of the dual time stepping loop to convergence compared to the conventional choice of initializing with the previous time step solution or an extrapolation in time. This procedure is repeated for all following time steps. Results for the pitching LANN wing at transonic flow conditions show a more than twofold reduction in the number of inner iterations of the flow solver to convergence. Despite the overhead caused by evaluating the reduced-order model (ROM) at every time step, the method results in a 38% saving in computational time without compromising accuracy, thus improving the overall efficiency for unsteady aerodynamics applications. Finally, several means to further improve the performance are also discussed, including updating the POD basis after every new time step.

Item URL in elib:https://elib.dlr.de/118963/
Document Type:Contribution to a Collection
Title:Accelerating Unsteady CFD Simulations Using a Minimum Residual Based Nonlinear Reduced Order Modeling Approach
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Ripepi, MatteoMatteo.Ripepi (at) dlr.deUNSPECIFIED
Görtz, StefanStefan.Goertz (at) dlr.deUNSPECIFIED
Date:10 February 2018
Journal or Publication Title:AeroStruct: Enable and Learn How to Integrate Flexibility in Design
Refereed publication:No
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Volume:138
DOI :10.1007/978-3-319-72020-3_15
Page Range:pp. 237-255
Editors:
EditorsEmail
Heinrich, RalfDLR
Publisher:Springer International Publishing
Series Name:Notes on Numerical Fluid Mechanics and Multidisciplinary Design
ISSN:978-3-319-72019-7
ISBN:978-3-319-72020-3
Status:Published
Keywords:CFD, aerodynamics, unsteady, transonic, convergence, ROM, POD, LANN wing
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:fixed-wing aircraft
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Simulation and Validation
Location: Braunschweig
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > CASE, BS
Deposited By: Görtz, Stefan
Deposited On:09 Mar 2018 09:51
Last Modified:09 Mar 2018 09:51

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