  Disruptions in tokamak plasmas may lead to the generation of runaway
electrons that have the potential to damage plasma-facing components. Improved
understanding of the runaway generation process requires interpretative
modelling of experiments. In this work we simulate eight discharges in the
ASDEX Upgrade and JET tokamaks, where argon gas was injected to trigger the
disruption. We use a fluid modelling framework with the capability to model the
generation of runaway electrons through the hot-tail, Dreicer and avalanche
mechanisms, as well as runaway electron losses. Using experimentally based
initial values of plasma current and electron temperature and density, we can
reproduce the plasma current evolution using realistic assumptions about
temperature evolution and assimilation of the injected argon in the plasma. The
assumptions and results are similar for the modelled discharges in ASDEX
Upgrade and JET, indicating that the implemented models are applicable to
machines of varying size, which is important for the modelling of future,
larger machines. For the modelled discharges in ASDEX Upgrade, where the
initial temperature was comparatively high, we had to assume that a large
fraction of the hot-tail runaway electrons were lost in order to reproduce the
measured current evolution.
