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Christer Fureby
Defence Security Systems Technology The Swedish Defence Research Agency (FOI) SE 147 25 Tumba, Stockholm, Sweden

Marco Kupiainen
Department of Numerical Analysis and Computer Science, Royal Institute of Technology S-144 00, Stockholm, Sweden


Flows around missiles, rockets and projectiles often experience baseflow separation. This means that the pressure behind the base is considerably lower than the freestream pressure, causing base drag that often constitutes a large portion of the total drag. The present study is motivated by the fact that most methods used for reducing the drag often also reduce the aerodynamic stability of the vehicle. Semianalytical methods and Reynolds Average Navier-Stokes (RANS) models often fail to provide accurate results for such flows, and therefore we use Large Eddy Simulations (LES) to investigate the flow physics of axisymmetric baseflow in a configuration for which experimental data is available for comparison. Good agreement with experimental data, with and without, base bleed is obtained for several LES models, suggesting that the details of the subgrid model are of less importance. The simulation data are also examined with the intention of increasing our knowledge of the underlying flow physics.