Effects of Numerical Errors in Large-Eddy Simulation of Transitional Wall-Bounded Flows

Effects of numerical errors in large-eddy simulations of transitional wall-bounded flows are investigated. Temporal and spatial laminar-to-turbulent transition in both channel and pipe flows is simulated using second- and fourth-order accurate finite-volume solvers based on the open-source CFD package OpenFOAM. Starting from unperturbed laminar or plug-flow profiles, it is found that, for centered finite-volume discretization, the onset of primary instability and the subsequent nonlinear pattern are highly sensitive to rounding errors and depend on a multitude of parameters: grid resolution, initial base flow, number of processors, flux reconstruction scheme, temporal integration time-step and subgrid-scale model. An attempt aimed at identifying the different contributions coming from each parameter, the various sources of error and their influence on the transition scenario is given in the study.