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Effects of numerical errors in large-eddy simulation of transitional wall-bounded flows

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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 finitevolume 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 paper. Although the results confirm the potential of large-eddy simulation for reflecting the true nature of fluid dynamics, they also emphasize that great care should be exercised when using this technique for transitional flows, especially in applications of practical
engineering importance.

Author(s):

Francesco Capuano    
Centro Italiano Ricerche Aerospaziali (CIRA)
Italy

Gennaro Coppola    
Dipartimento di Ingegneria Industriale (DII) - Università di Napoli Federico II
Italy

Luigi de Luca    
Dipartimento di Ingegneria Industriale (DII) - Università di Napoli Federico II
Italy