  Turbulence evolution in a density-stratified medium differs from that of
homogeneous isotropic turbulence described by the Kolmogorov picture. We
evaluate the degree of this effect in the intracluster medium (ICM) with
hydrodynamical simulations. We find that the buoyancy effect induced by ICM
density stratification introduces qualitative changes to the turbulence energy
evolution, morphology, and the density fluctuation - turbulence Mach number
relation, and likely explains the radial dependence of the ICM turbulence
amplitude as found previously in cosmological simulations. A new channel of
energy flow between the kinetic and the potential energy is opened up by
buoyancy. When the gravitational potential is kept constant with time, this
energy flow leaves oscillations to the energy evolution, and leads to a
balanced state of the two energies where both asymptote to power-law time
evolution with slopes shallower than that for the turbulence kinetic energy of
homogeneous isotropic turbulence. We discuss that the energy evolution can
differ more significantly from that of homogeneous isotropic turbulence when
there is a time variation of the gravitational potential. Morphologically, ICM
turbulence can show a layered vertical structure and large horizontal vortical
eddies in the central regions with the greatest density stratification. In
addition, we find that the coefficient in the linear density fluctuation -
turbulence Mach number relation caused by density stratification is in general
a variable with position and time.
