Active Aerodynamic Control of a Separated Flow Using Streamwise Synthetic Jets
Journal article, 2019

LES simulations at Re=1×10^5 and wind tunnel experiments at Re=5×10^5 were con-ducted to investigate the beneficial effect of an active flow control (AFC) technique on theaerodynamic performance of a simplified truck geometry. The paper involves the investiga-tion of a synthetic jet actuator characterized by periodic blowing and suction that defines azero net mass flux flow control mechanism. The actuation aims to suppress the flow sep-aration occurring at the A-pillar (front rounded corner) of a truck cabin. The work flow isdefined as it follows. First, LES at low Reynolds number are conducted for different dispo-sition of the actuation slots. The results show a beneficial effect when the actuation slots arepositioned in streamwise direction compared to spanwise (vertical) direction. Second, basedon the previous considerations, wind tunnel experiments are conducted to verify and sup-port the numerical findings. Both numerical solutions and experimental data show the sametrend and the superiority of the streamwise slots actuation when compared to traditional ver-tical slot actuation. In particular, this work shows the weakness of a vertical slot actuation,when its location is not optimized. A small change in its positioning greatly worsen the effi-cacy of the separation control in terms of drag reduction and separation bubble length. Theslot location directly affects the length of the separated flow region which its reduction canvary between 40–70% based on the positioning. Conversely, a streamwise actuation, span-ning a larger portion of the curvature of a rounded A-pillar, is not affected by this behaviourand contributes up to 80% of the recirculation bubble reduction measured in the unactuatedcase. The effect of the location change and the orientation of a zero net mass flux jet slot istherefore investigated and discussed in this work.

Flow control

Vehicle aerodynamics

Synthetic jets

Bluff body aerodynamics

Drag reduction


Guglielmo Minelli

Chalmers, Mechanics and Maritime Sciences, Fluid Dynamics

Mikhail Tokarev

Institute of Thermophysics SB RAS, Novosibirsk, Russia

Jie Zhang

Chalmers, Mechanics and Maritime Sciences, Fluid Dynamics

Tanghong Liu

Central South University

Valery Chernoray

Chalmers, Mechanics and Maritime Sciences, Fluid Dynamics

Branislav Basara


Chalmers, Mechanics and Maritime Sciences

Sinisa Krajnovic

Chalmers, Mechanics and Maritime Sciences, Fluid Dynamics

Flow, Turbulence and Combustion

1386-6184 (ISSN) 1573-1987 (eISSN)

Subject Categories

Other Mechanical Engineering

Applied Mechanics

Fluid Mechanics and Acoustics

Areas of Advance



Chalmers Laboratory of Fluids and Thermal Sciences



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