Bursting detection by Variable-Interval Time-Averaging (VITA) on spanwise oscillated turbulent channel flow

Karabuk University, Engineering Faculty, 78050 Karabuk, Turkey

Abstract

The main aim of the study is to detect the bursting phenomenon in spanwise oscillated Lorentz force applied turbulent channel flow. Regarding the biggest reason of the turbulence production is known as the bursting phenomenon, detecting the decrease on it could be a very effective tool as an estimation of the effectiveness of the applied control strategy to the flow. The data gained by DNS (Direct numerical simulations) at low Reynolds number (Re_τ = 180 based on the wall-shear velocity and channel half width). The Variable- Interval Time-Averaging (VITA) technique has been applied to three different streamwise locations for both applied force and no-force cases. The Lorentz force applied only to the lower wall. In first step the very well known drag reduction is observed, we compared the drag reduction results for the applied force and no-force cases both for the lower and upper wall of the channel. The bursting detection results are given statistically, which clearly shows that bursting phenomenon frequency tend to decrease as a result of the applied Lorentz force. It is also has shown that associated turbulence production has similar trend.