Response of turbulent energy spectrum and flow structures when vortical motion of a certain scale is suppressed by artificial forcing

The energy cascade in turbulence is explored through a novel approach in which the vortical structures of a certain scale in the inertial subrange, colored by yellow, is forcibly suppressed. Their disappearance leads to a slight increase in kinetic energy in the larger scale range and a decrease in the smaller scale range. The vortex-tracking analysis reveals that the vortices twice as large as the target, colored by blue, exhibit smaller curvatures and longer lifespans, while no remarkable changes are found for the vortices that are four times larger, colored by red. These findings indicate that the larger vortices are locally bent by the smaller vortices, shortening their lifespans.