Inherent and Model-Form Uncertainty Analysis for CFD Simulation of Synthetic Jet Actuators

Abstract

using a fourth order polynomial chaos expansion (PCE). A global sensitivity analysis with Sobol indices was utilized to rank the importance of each uncertainty source to the overall output uncertainty. The results indicated that for the long-time averaged separation bubble size, the uncertainty in turbulence model had a dominant contribution, which was also observed in the long-time averaged skin friction coecients at three selected locations. The mixed uncertainty results for phase averaged x-velocity distributions at three selected locations showed that the 95% condence interval (CI) could generally envelope the experimental data. The Sobol indices showed that near the wall, the uncertainty in turbulence model had a main inuence on the x-velocity, while approaching the main stream, the uncertainty in free stream velocity became a larger contributor. The mixed uncertainty quantication approach demonstrated in this study can also be applied to other computational uid dynamics problems with inherent and model-form input uncertainities.