  The axially symmetric, swirl-free gas dynamics and interlinked motion of a
cork stopper provoked by the opening of a champagne bottle are modelled
rigorously and studied numerically. The experimental study by Liger-Belair,
Cordier \& Georges (Science Advances, 5(9), 2019) animated the present
investigation. Inspection analysis justifies the inviscid treatment of the
expanding jet of air enriched with dissolved carbonic acid gas initially
pressurised in the bottle. Solving the resulting Euler equations is facilitated
through the open-source software "Clawpack". Specific enhancements allow for
resolving the emerging supersonic pockets, associated with surprisingly complex
shock structures, as well as the gas-stopper interaction with due accuracy. Our
experimental effort provided modelling the frictional behaviour, constitutive
law and reversible (de-)compression of cork. Initially, the gas expands inside
the bottleneck yet sealed by the stopper, hence accelerated by the gas but
decelerated by dry sliding friction. Once the stopper has passed the bottle
opening, the jet rapidly assumes locally supersonic speed, where a complex
shock pattern is detected. Special attention is paid to the formation and
dissolution of one or even two Mach discs between the opening and the released
stopper. These simulated dynamics are found to be in fairly good agreement with
recent experimental findings. It also provides a first insight into the
generation of the typical popping sound.
