Kinematics of filaments in cooling flow clusters and heating by mixing
  We compare a recent study of the kinematics of optical filaments in three
cooling flow clusters of galaxies with previous numerical simulations of
jet-inflated hot bubbles, and conclude that the velocity structure functions of
the filaments better fit direct excitation by the jets than by turbulent
cascade from the largest turbulent eddies. The observed velocity structure
functions of the optical filaments in the three clusters are steeper than that
expected from a classical cascade in turbulent dissipation. Our
three-dimensional (3D) hydrodynamical simulations show that as the jets inflate
bubbles in the intracluster medium (ICM), they form vortexes in a large range
of scales. These vortexes might drive the ICM turbulence with eddies of over
more than an order of magnitude in size. A direct excitation of turbulence by
the vortexes that the jets form and the slow turbulent dissipation imply that
heating the ICM by mixing with hot bubbles is more efficient than heating by
turbulent dissipation.
