Large-eddy simulations of the flow past a bluff-body with active flow control based on trapped vortex cells at Re = 50000

Abstract

We investigate a novel flow control concept, which allows to govern bluff-body wake dynamics and the laminar–turbulent transition by suppressing vortex shedding and obtaining the mostly detached flow. Large-eddy simulations past a bluff-body (BB) with and without an active flow control (AFC) system at a Reynolds number of 50000 and zero angle of attack are presented. The BB is designed of a semicircular cylinder of the finite span-wise length with two hemispheres attached to its lateral sides. The BB has a negative lift force because of detached and attached massive recirculation zones, which respectively, originate from separation of the laminar boundary layers from its upper side and the leading edge. AFC is based on the two trapped vortex cells implemented at the upper side of BB to control the behavior of boundary layers. The chosen AFC demonstrates almost the detached flow and suppresses the vortex street. The lift-to-drag ratio of BB with integrated AFC is calculated as 1.5 (compared to -1 obtained for the simple BB) coupled with reasonable energy losses of 10% in terms of the total drag coefficient. Finally, present findings demonstrate the potential of the concept and provide the basis for its further development.