  We study the decay of high-Reynolds number Taylor-Couette turbulence, i.e.
the turbulent flow between two coaxial rotating cylinders. To do so, the
rotation of the inner cylinder (Re$_i=2 \times 10^6$, the outer cylinder is at
rest) is stopped within 12 s, thus fully removing the energy input to the
system. Using a combination of laser Doppler anemometry and particle image
velocimetry measurements, six decay decades of the kinetic energy could be
captured. First, in the absence of cylinder rotation, the flow-velocity during
the decay does not develop any height dependence in contrast to the well-known
Taylor vortex state. Second, the radial profile of the azimuthal velocity is
found to be self-similar. Nonetheless, the decay of this wall-bounded
inhomogeneous turbulent flow does not follow a strict power law as for decaying
turbulent homogeneous isotropic flows, but it is faster, due to the strong
viscous drag applied by the bounding walls. We theoretically describe the decay
in a quantitative way by taking the effects of additional friction at the walls
into account.
