Stochastic analysis of the effects of inlet velocity conditions on the evolution of spatially evolving mixing layers

etc15 Tracking Number 342

The sensitivity of the evolution of the spatially evolving mixing layer test case to inlet conditions parameters is studied in the present work. The analysis is performed combining DNS simulations and a response surface stochastic approach. The angle between the two asymptotic streams $\theta$ and the parameter $\alpha = (U1 - U2)/(U1 + U2)$ are identified as parameters of interest and they are considered as random variables. The uncertainty propagated over the output quantities, such as the average velocity $U$, is then investigated. The analysis of the results indicates that different physical regimes can evolve from the initial conditions investigated. In particular, non linear effects streaming from interactions between $\theta$ and $\alpha$ are observed. These effects are not captured by classical DNS analyses of the spatially evolving mixing layer test case