The contraction of a two-dimensional infinite-long flat air sheet in a liquid environment at a capillary-inertial regime with an Ohnesorge number O h ⩽ 0.01 was investigated numerically. The contraction velocity first increases to a maximum and then decreases and follows a scaling U * ∼ t * − 0.2 . In this range of Oh number, pinch-off and oscillation were always observed, and two pinch-off mechanisms were identified as end-pinching (O h ⩽ 0.006) and oscillation-induced pinch-off (O h ⩾ 0.007), which also correspond to two oscillation regimes of the rim. Different modes of vortex shedding and merging, co-rotating, and separation of vortices are observed; the interaction between the rim and the vortices is responsible for the complicated contraction dynamics. [ABSTRACT FROM AUTHOR]