Numerical Modeling of Breaking Waves and Cross-Shore Currents on Barred Beaches

Abstract

A process-based numerical model has been used to study nearshore hydrodynamics on barred beaches. A laboratory experiment with an offshore bar migration case followed by an onshore bar migration is simulated. A new mechanism is incorporated in the model accounting for the breaking-wave persistence improving model performance for wave properties, particularly in the bar-trough region. A cross-shore variation of the breaking-wave parameter is introduced to the dissipation model. The effects of the surface shape parameter and a roller lag on radiation stresses and mean water-level predictions are investigated and found to improve the mean water-level predictions. The cross-shore variation of the momentum balance is presented to illustrate the variation of forcing for the undertow current. The persistence length and the roller lag mechanisms are shown to be important for predictions of the undertow currents on barred beaches and the current predictions are improved once both methods are used.