Analyses for the second aeroelastic prediction workshop using the EZNSS code

The paper presents analyses that were performed with the EZNSS flow solver for the second Aeroelastic Prediction Workshop.The reference test cases for theAeroelastic PredictionWorkshop are based on twowind-tunnel experiments of the Benchmark SupercriticalWing, including a flutter test and forced excitation tests. Three cases are addressed at different transonic flow conditions: two cases at lower Mach numbers of 0.7 and 0.74 and 3 and 0 deg angles of attack, respectively; and onemorephysically complex case atMach 0.85 and a 5 deg angle of attack.The cases are analyzedwith the EZNSS code, using several computational setups and turbulence models. The simulations are able to predict relatively accurately the flutter response and the response to prescribed motion at the lowerMach number. The higher- Mach-number case, whichinvolves a strong shock, separatedflowbehindthe shock, andsome flowunsteadiness, ismore challenging. In the static analysis, different turbulencemodels yield different upper-surface shock positions, and none of themodels are able to capture accurately the pressure recovery behind the shock.However, the unsteady aerodynamic response to prescribed pitchmotion is simulated with good correlation to the wind-tunnel data. The paper also presents flutter predictions based on unsteady aerodynamic reduced-ordermodeling, thus validating and assessing the efficiency of the reduced-order modeling and the flutter prediction methodology.