However, the output standard deviation for drag and pitching moment can become large when the transition location changes rapidly with changing FSTI. In most cases, the response is nearly Gaussian and the mean response is not too dierent from the discrete FSTI response without uncertainty. The UQ analysis shows how varying these parameters affects the sensitivies of the aerodynamic coefficients to uncertainty in FSTI. Rather than run a separate CFD run for each Monte Carlo run, all of the results can be attained virtually instantaneously via the surrogate surface. A surrogate surface is therefore generated using a parametric study using the in-house flow solver OVERTURNS. However, the Monte Carlo method would require hundreds of thousands of CFD calculations in order to converge to the correct results. The airfoil data samples are taken from the database of UIUC Applied Aerodynamic Group 30, which covers a wide range of airfoil types from real-world designs. In this work, the Monte Carlo method is used to calculate the sensitivities of the aerodynamic coefficients to Gaussian distributions of uncertainty in FSTI over a range of angles of attack (AOA) at various Reynolds numbers and Mach numbers. The primary objective of the present work is to determine the effect of uncertainty in freestream turbulence intensity (FSTI) on the coefficients of lift, drag, and moment for four different airfoils: S809, NACA 0012, SC1095, and RC(4)-10. The airfoil polar data at each blade analysis node is specified via input BlAFID in the AeroDyn blade input file. ![]() The effects of uncertainty in CFD can be determined through application of Uncertainty Quantification (UQ). ![]() However, this uncertainty is often omitted from the CFD results. In the physical world, these input conditions often have some uncertainty associated with them. Traditional CFD results have a number of freestream inputs.
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