Resumo: The mathematical model consists of the nonstationary incompressible Navier-Stokes equation which has to be solved numerically in a time-dependent domain. First, we discuss the space discretization by stable finite pairs to approximate the velocity and pressure, respectively. The resulting system of ordinary differential equations is discretized in time by the fractional step $\theta$-scheme. The ALE-(Arbitrary Lagrangian-Eulerian)-Approach is used to handle the space discretization on meshes of time-dependent domains. A special treatment of the curvature term avoids the direct calculation of second derivatives of the parametrization of the boundary. As an testexample we consider the oscillations of a water drop driven by surface tension around the equilibrium state.