A Critical Look at Dynamic Simulation of Viscous Flow,
LOCKHEED MISSILES AND SPACE CO INC SUNNYVALE CA
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A critical examination is made of the classic role of lthe wind tunnel as a tool for simulation of the free flight aerodynamics. That the equivalence concept established for steady flow is not valid for unsteady flow is no great surprise. More surprising, probably, is the fact that simulation of the relative velocity time history, which assures simulation of the inciscid unsteady aerodynamics, will in many cases not assure simulation of the unsteady viscous flow. In the case of flow separation and associated hysteresis the lack of simulation of the transient viscous flow can sometimes even generate the incorrect final steady state flow condition. Only close attention to the simulation of the unsteady boundary condition at the vehicle surface can assure the utility of experimental and numerical results for prediction of full scale unsteady viscous flow characteristics.