The increase in mean water level due to the presence of breaking waves
In fluid dynamics, wave setup is the increase in meanwater level due to the presence of breaking waves. Similarly, wave setdown is a wave-induced decrease of the mean water level before the waves break (during the shoaling process). For short, the whole phenomenon is often denoted as wave setup, including both increase and decrease of mean elevation. This setup is primarily present in and near the coastal surf zone. Besides a spatial variation in the (mean) wave setup, also a variation in time may be present – known as surf beat – causing infragravity waveradiation.[1][2]
Wave setup can be mathematically modeled by considering the variation in radiation stress.[3] Radiation stress is the tensor of excess horizontal-momentumfluxes due to the presence of the waves.[4][5]