The motion of a thin liquid sheet subjected to the effects of surface tension and external gaseous pressure is studied. Equations of motion are constructed by essentially ignoring the interal flow of the liquid in the layer. For an axisymmetric case, for example, the system is reduced to a set of coupled nonlinear partial differential equations depending on time and only one spatial variable, which can be solved numerically as an initial‐boundary‐value problem. Here, a review of the application of this approach to two different problems is presented. The first is the instability of an annular jet, in which a cylindrical liquid sheet emanating from an annular nozzle and enclosing a gas stream breaks up into liquid shells downstream. The second is the centering mechanism of such a liquid shell under capillary oscillations. Reasonable results have been obtained from the numerical studies of these problems.