A new technique for the advection of liquid domains with free surfaces is developed. This technique is based on describing the liquid surface by a spine function h(alpha, t), with a being the angle measured from one axis at time t. After discretization, the spines h(i)(alpha(i), t(i)) subdivide the liquid zone into conical subvolumes. The volume of each of the subvolumes is updated using the local velocities at the interface of every two neighboring subvolumes. A technique is developed to calculate the new spines based on the updated subvolumes. The method is referred to as the spine-flux method (SFM) and it is implemented in a Galerkin finite element method with penalty formulation. The problems of drop oscillation and drop collision are utilized to show the accuracy and efficiency of the technique. (C) 1995 Academic Press, Inc.