The present work focuses on a passive strategy consisting in the introduction of properly contoured transverse grooves to delay the flow separation occurring on a boat-tailed bluff body before its sharp-edged base. We consider a two-dimensional body having a cross-section with a 3:1 elliptical forebody and a rectangular main part followed by a circular-arc boat tail. We carry out Variational Multiscale Large Eddy Simulations at Re = Du∞/v = 9.6 × 104. A boat-tail drag reduction of the order of 9.7% is produced by the significant delay of the flow separation caused by the groove and by the consequent increase of the base pressure. This effect is mainly due to the relaxation of the no-slip condition over the small and steady recirculation region inside the groove, which reduces the momentum losses near the wall and thus delays boundary layer separation. The flow control device is also robust to small variations of the groove location and depth.
- Fluids Engineering Division
Flow Separation Control and Drag Reduction for a Two-Dimensional Boat-Tailed Bluff Body Through Transverse Grooves
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Mariotti, A, Buresti, G, & Salvetti, MV. "Flow Separation Control and Drag Reduction for a Two-Dimensional Boat-Tailed Bluff Body Through Transverse Grooves." Proceedings of the ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. Volume 1: Flow Manipulation and Active Control; Bio-Inspired Fluid Mechanics; Boundary Layer and High-Speed Flows; Fluids Engineering Education; Transport Phenomena in Energy Conversion and Mixing; Turbulent Flows; Vortex Dynamics; DNS/LES and Hybrid RANS/LES Methods; Fluid Structure Interaction; Fluid Dynamics of Wind Energy; Bubble, Droplet, and Aerosol Dynamics. Montreal, Quebec, Canada. July 15–20, 2018. V001T08A007. ASME. https://doi.org/10.1115/FEDSM2018-83458
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