Résumé
This paper studies the propagation of rounding errors in large-eddy simulation and shows that instantaneous flowfields produced by large-eddy simulation are partially controlled by these rounding errors and depend on multiple parameters: number of processors used for parallel simulation (even in an explicit code), changes in initial conditions (even of the order of machine accuracy), machine precision (simple, double, or quadruple), etc. Using a laminar Poiseuille pipe flow, a fully developed turbulent channel flow, and a complex burner geometry as test cases, results show that only turbulent flows exhibit a high sensitivity to these parameters. These results confirm that large-eddy simulation reflects the true nature of turbulence insofar as it may exponentially amplify infinitely small perturbations on initial conditions in time. However, they highlight an often overlooked limitation of large-eddy simulation in terms of validation and prediction of unsteady phenomena.