The University of Southampton
University of Southampton Institutional Repository

Overview of the 2018 Workshop on Iterative Errors in Unsteady Flow Simulations

Overview of the 2018 Workshop on Iterative Errors in Unsteady Flow Simulations
Overview of the 2018 Workshop on Iterative Errors in Unsteady Flow Simulations
Two Workshops were held at the ASME V&V Symposiums of 2017 and 2018 dedicated to Iterative Errors in Unsteady Flow Simulations. The focus was on the effect of iterative errors on numerical simulations performed with implicit time integration, which require the solution of a non-linear set of equations at each time step. The main goal of these Workshops was to create awareness to the problem and to confirm that different flow solvers exhibited the same trends. The test case was a simple two-dimensional, laminar flow of a single-phase, incompressible, Newtonian fluid around a circular cylinder at the Reynolds number of 100. A set of geometrically similar multi-block structured grids was available and boundary conditions to perform the simulations were proposed to the participants. Results from seven flow solvers were submitted, but not all of them followed exactly the proposed conditions. One set of results was obtained with adaptive grid and time refinement using triangular elements (CADYF) and another used a compressible flow solver with a dual time stepping technique and a Mach number of 0.2 (DLR-Tau). The remaining five submissions were obtained with five different incompressible flow solvers (ANSYS CFX 14.5, pimpleFoam, ReFRESCO, SATURNE, STAR CCM+ v12.06.010-R8) using implicit time integration in the proposed grids. The results obtained in this simple test case showed that iterative errors may have a significant impact on the numerical accuracy of unsteady flow simulations performed with implicit time integration. Iterative errors can be significantly larger (one to two orders of magnitude) than the residuals and/or solution changes used as convergence criteria at each time step. The Courant number affected the magnitude of the iterative errors obtained in the proposed exercise. For the same iterative convergence criteria at each time step, increasing the Courant number tends to increase the iterative error.
Eça, L.
97c0672c-49ed-4c7b-8850-c3a95b219868
Vaz, G.
452ca6d6-a565-4255-aa7b-022c21ad9b1c
Hoekstra, M.
64f10033-3234-4b22-b757-6d25ebd0304f
Pal, S.
46a4149e-73c6-441f-9a72-45f463aeb1af
Muller, E.
1390315f-ec5e-47a1-96d4-b14c4c4b9d05
Pelletier, D.
6d4f57b3-5598-4ac4-b8d0-8491fd55a7e7
Bertinetti, A.
ec7ac87b-24b1-4f4e-9cdc-063b000692d6
Difonzo, R.
432abbc6-57d9-42bc-84ae-608aa0847c2d
Savoldi, L.
24635271-9d3c-440a-ac1b-dbd268f41706
Zanino, R.
9a44adc2-bf68-41a3-91b2-0de34b03ba35
Zappatore, A.
4d97d367-5d1d-4042-8ef4-fcb03aa65541
Chen, Y.
7846843f-afb6-419c-b85e-746cac623957
Maki, K.J.
ebcbddb8-e200-4b7d-8b9c-867fa0677529
Ye, H.
5134982a-e1e4-45de-82d0-8b88554ae45e
Drofelnik, Jernej
e785f695-61ef-4afc-bf0a-9dc7966f5516
Moss, Benjamin
c07d2cb8-3558-46d8-a22a-0fb38d92db94
Da Ronch, Andrea
a2f36b97-b881-44e9-8a78-dd76fdf82f1a
Eça, L.
97c0672c-49ed-4c7b-8850-c3a95b219868
Vaz, G.
452ca6d6-a565-4255-aa7b-022c21ad9b1c
Hoekstra, M.
64f10033-3234-4b22-b757-6d25ebd0304f
Pal, S.
46a4149e-73c6-441f-9a72-45f463aeb1af
Muller, E.
1390315f-ec5e-47a1-96d4-b14c4c4b9d05
Pelletier, D.
6d4f57b3-5598-4ac4-b8d0-8491fd55a7e7
Bertinetti, A.
ec7ac87b-24b1-4f4e-9cdc-063b000692d6
Difonzo, R.
432abbc6-57d9-42bc-84ae-608aa0847c2d
Savoldi, L.
24635271-9d3c-440a-ac1b-dbd268f41706
Zanino, R.
9a44adc2-bf68-41a3-91b2-0de34b03ba35
Zappatore, A.
4d97d367-5d1d-4042-8ef4-fcb03aa65541
Chen, Y.
7846843f-afb6-419c-b85e-746cac623957
Maki, K.J.
ebcbddb8-e200-4b7d-8b9c-867fa0677529
Ye, H.
5134982a-e1e4-45de-82d0-8b88554ae45e
Drofelnik, Jernej
e785f695-61ef-4afc-bf0a-9dc7966f5516
Moss, Benjamin
c07d2cb8-3558-46d8-a22a-0fb38d92db94
Da Ronch, Andrea
a2f36b97-b881-44e9-8a78-dd76fdf82f1a

Eça, L., Vaz, G., Hoekstra, M., Pal, S., Muller, E., Pelletier, D., Bertinetti, A., Difonzo, R., Savoldi, L., Zanino, R., Zappatore, A., Chen, Y., Maki, K.J., Ye, H., Drofelnik, Jernej, Moss, Benjamin and Da Ronch, Andrea (2020) Overview of the 2018 Workshop on Iterative Errors in Unsteady Flow Simulations. Journal of Verification, Validation and Uncertainty Quantification, 5, [021006].

Record type: Article

Abstract

Two Workshops were held at the ASME V&V Symposiums of 2017 and 2018 dedicated to Iterative Errors in Unsteady Flow Simulations. The focus was on the effect of iterative errors on numerical simulations performed with implicit time integration, which require the solution of a non-linear set of equations at each time step. The main goal of these Workshops was to create awareness to the problem and to confirm that different flow solvers exhibited the same trends. The test case was a simple two-dimensional, laminar flow of a single-phase, incompressible, Newtonian fluid around a circular cylinder at the Reynolds number of 100. A set of geometrically similar multi-block structured grids was available and boundary conditions to perform the simulations were proposed to the participants. Results from seven flow solvers were submitted, but not all of them followed exactly the proposed conditions. One set of results was obtained with adaptive grid and time refinement using triangular elements (CADYF) and another used a compressible flow solver with a dual time stepping technique and a Mach number of 0.2 (DLR-Tau). The remaining five submissions were obtained with five different incompressible flow solvers (ANSYS CFX 14.5, pimpleFoam, ReFRESCO, SATURNE, STAR CCM+ v12.06.010-R8) using implicit time integration in the proposed grids. The results obtained in this simple test case showed that iterative errors may have a significant impact on the numerical accuracy of unsteady flow simulations performed with implicit time integration. Iterative errors can be significantly larger (one to two orders of magnitude) than the residuals and/or solution changes used as convergence criteria at each time step. The Courant number affected the magnitude of the iterative errors obtained in the proposed exercise. For the same iterative convergence criteria at each time step, increasing the Courant number tends to increase the iterative error.

Text
paper_Workshops_iterative_rev1 - Accepted Manuscript
Download (1MB)
Text
VVUQ-20-1014_AuthorProof - Version of Record
Restricted to Repository staff only
Request a copy

More information

Accepted/In Press date: 2 June 2020
e-pub ahead of print date: 28 August 2020

Identifiers

Local EPrints ID: 441670
URI: http://eprints.soton.ac.uk/id/eprint/441670
PURE UUID: fe0aa884-5780-4a90-b69d-0c7e3eb74572
ORCID for Andrea Da Ronch: ORCID iD orcid.org/0000-0001-7428-6935

Catalogue record

Date deposited: 23 Jun 2020 16:55
Last modified: 11 Mar 2022 05:02

Export record

Contributors

Author: L. Eça
Author: G. Vaz
Author: M. Hoekstra
Author: S. Pal
Author: E. Muller
Author: D. Pelletier
Author: A. Bertinetti
Author: R. Difonzo
Author: L. Savoldi
Author: R. Zanino
Author: A. Zappatore
Author: Y. Chen
Author: K.J. Maki
Author: H. Ye
Author: Jernej Drofelnik
Author: Benjamin Moss
Author: Andrea Da Ronch ORCID iD

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×