Uncertainty quantification in LES of a turbulent bluff-body stabilized flame

We address the forward uncertainty quantification problem in large eddy simulation (LES) of a turbulent non-premixed hydrocarbon flame, focusing on parametric uncertainty. More specifically, we examine the effect of uncertainty in the Smagorinsky coefficient and turbulent Prandtl and Schmidt numbers on specific quantities of interest. To conduct this analysis 25 LES simulations are performed, from which a surrogate model is built, based on polynomial chaos expansion, for the quantities of interest. This enables global sensitivity analysis and forward propagation of uncertainty, providing marginal and joint distributions on the quantities of interest. A non-intrusive method is used to construct the surrogate models, avoiding the need to modify the deterministic LES forward solver. The accuracy of the surrogates is examined using global error measures. The results provide insights into the underlying structure of the LES simulation, the impact of varying parameters on specific observables, and correlations among different quantities of interest. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.