  We investigate the influence of dispersed solid spherical particles on the
largest scales of the turbulent Arnold-Beltrami-Childress (ABC) flow. The ABC
flow is an ideal instance of a complex flow: it does not have solid boundaries,
but possesses an inhomogeneous and three-dimensional mean shear. By tuning the
parameters of the suspension, we show that particles deviate towards
quasi-straight trajectories and exhibit anomalous transport. In doing this,
they enhance the mean-flow energy and modulate the largest scales of the flow
towards an anisotropic and quasi two-dimensional state.
