  In recent experiments, the relaxation dynamics of highly oblate, turbulent
Bose-Einstein condensates (BECs) was investigated by measuring the vortex decay
rates in various sample conditions [Phys. Rev. A $\bf 90$, 063627 (2014)] and,
separately, the thermal friction coefficient $\alpha$ for vortex motion was
measured from the long-time evolution of a corotating vortex pair in a BEC
[Phys. Rev. A $\bf 92$, 051601(R) (2015)]. We present a comparative analysis of
the experimental results, and find that the vortex decay rate $\Gamma$ is
almost linearly proportional to $\alpha$. We perform numerical simulations of
the time evolution of a turbulent BEC using a point-vortex model equipped with
longitudinal friction and vortex-antivortex pair annihilation, and observe that
the linear dependence of $\Gamma$ on $\alpha$ is quantitatively accounted for
in the dissipative point-vortex model. The numerical simulations reveal that
thermal friction in the experiment was too strong to allow for the emergence of
a vortex-clustered state out of decaying turbulence.
