Waves and Currents on Accretional Barred Beaches

This paper analyzes the waves and currents on beaches with rhythmic or crescentic bars. The goal is to determine under what conditions does the flow in the trough between the bar and shore show similarities with the flow patterns observed on accretional beaches. The nearshore circulation numerical model system SHORECIRC is used for this study. The crescentic shape of the bars is found to refract the waves toward the wide section of the bars driving currents toward the narrow sections of the bar generating rip currents. Channels formed on the narrow parts of the bar reinforce the rip currents within these channels. It is found that waves with an incident angle create stronger flows in the trough. In addition, larger depths over the bar are also found to generate stronger flow in the trough. The flow patterns are seen to be insensitive to the wave height and period for the particular conditions studied.