A multi-fidelity approach to sensitivity estimation in large eddy simulation

An approach to compute approximate sensitivities in a large eddy simulation (LES) is proposed and assessed. The method is based on solving a linearized

mean equation, where the mean equation is defined based on the LES solution. This requires closure modeling which makes the computed sensitivities

approximate; the closure modeling is based on computing the inferred eddy viscosity from the LES data. The method is assessed for the flow over a

NACA0012 airfoil at different angles of attack, with the Reynolds number as the varying parameter and the lift and drag coefficients as the quantities-

of-interest. The results show the importance of accurate closure modeling, specifically that treating the eddy viscosity as “frozen” is insufficiently accurate.