Energy harvesting

Passive control of a single flag using two side-by-side flags (Jeong & Lee 2017, IJHFF) IJHFF:  International Journal of Heat and Fluid Flow

• In order to control a single flag passively, we utilize the distinct dynamics of two side-by-side flags, characterized by in-phase and out-of-phase flapping modes depending on their spanwise gap distance (Gy).

• When the two side-by-side flags are in an in-phase flapping mode with a small Gy, the flapping amplitude of a single downstream flag is highly enhanced due to synchronization between the vortices shed from the upstream and downstream flags. 

• However, when the two upstream flags flap in an out-of-phase flapping mode with a large Gy, the flapping of the single flag is significantly weakened with a reduction of the dominant flapping frequency.

• The proposed passive control concept of a single flag using two side-by-side flags is applicable to the development of energy harvesting systems to extract more energy and flapping control systems to suppress vibration.