A circulation description of a rip current neck

This paper considers wave-driven rip currents from a circulation–vorticity point of view. A highly simplified description of rip currents using continuous generation of point vortices at fixed locations is found to have a wide range of applicability around the rip neck. Rip scaling becomes straightforward, and is seen to collapse to a single form. Numerical experiments with this simplified system have the ability to predict well startup transients including previously unexplained peaks, and frequencydependent effects of wave groups on rip currents. Quantitative mean currents in the rip neck are represented moderately well by this theory.