ON THE ACCURACY OF IMPULSE METHODS FOR FLUID-FLOW

A Lagrangian numerical method based on impulse variables is analyzed. The relation between discrete impulse vectors and vortex dipoles with a prescribed dipole moment is presented and used to adapt the high-acc uracy cutoff functions of vortex methods for use in impulse-based meth ods. The long-time implementation of the impulse method is shown to co ntain a source of error whose growth in time leads to a severe loss of accuracy in interior flows. Applications for which impulse methods ar e well suited are identified.