Overview of the 2018 Workshop on Iterative Errors in Unsteady Flow Simulations - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue The Journal of Verification, Validation and Uncertainty Quantification (VVUQ) Année : 2020

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

L. Eça
  • Fonction : Auteur
G. Vaz
  • Fonction : Auteur
M. Hoekstra
  • Fonction : Auteur
S. Pal
  • Fonction : Auteur
Etienne Muller
A. Bertinetti
  • Fonction : Auteur
R. Difonzo
  • Fonction : Auteur
L. Savoldi
  • Fonction : Auteur
R. Zanino
  • Fonction : Auteur
A. Zappatore
  • Fonction : Auteur
Y. Chen
  • Fonction : Auteur
K. Maki
  • Fonction : Auteur
H. Ye
  • Fonction : Auteur
Jernej Drofelnik
  • Fonction : Auteur
Benjamin Moss
  • Fonction : Auteur
Andrea da Ronch
  • Fonction : Auteur

Résumé

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 nonlinear 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 multiblock 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 (ansyscfx 14.5, pimplefoam, refresco, saturne, starccm+ 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.

Dates et versions

hal-03260820 , version 1 (15-06-2021)

Identifiants

Citer

L. Eça, G. Vaz, M. Hoekstra, S. Pal, Etienne Muller, et al.. Overview of the 2018 Workshop on Iterative Errors in Unsteady Flow Simulations. The Journal of Verification, Validation and Uncertainty Quantification (VVUQ), 2020, 5 (2), ⟨10.1115/1.4047922⟩. ⟨hal-03260820⟩
7 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More