Beach Process Modeling Based on Visco-Elastic- Plastic Model of Mud

A cross-shore time dependent beach transformation model has been developed based on the assumption of visco-elastic-plastic behavior of mud. Mud is considered to be viscoelastic when shear stress in mud layer is smaller than yield stress and it is assumed to be visco-plastic when the stress exceeds the yield level. The mud layer is divided to sub layers for featuring the changes of properties in the elevation of layer. The wave energy dissipation rate of a horizontal muddy bed has been extended to mild slope and it has been added to the energy dissipation term due to wave breaking for formulation of wave decay in the surf zone. The hydrodynamic model can successfully combine the various effects of mud bed, water depth denease or shoaling and wave breaking on the wave height changes. The results for different fluid mud depths show that water depth may decrease or increase before the breaking point depending on the governing factor. The dynamic beach profile is finally computed from the &d mass transport rate distribution by using the mass conservation equation and considering the local redistribution of fluid mud due to gravity.

Keywords:

visco-elastic-plastic behavior , wave decay , mud bed , beach profile , redistribution of fluid mud