Published in:Journal of Geophysical Research: Oceans
Language:
English
DOI:
10.1029/2009jc005552
ISSN:
0148-0227
Origination:
Footnote:
Description:
<jats:p>Many previous studies consider wave attenuation over muddy seabeds and bottom boundary layer fluid‐mud transport as two distinct research topics. Hence, various processes related to the physics of wave‐mud interaction, such as turbulence‐sediment interactions, rheological stresses, and nonlinear wave‐wave interactions are incorporated rather artificially. The aim of this work is to present a new modeling approach which allows for the resolution of nonlinear wave propagation and bottom boundary layer mud transport with a single set of governing equations and closures. By adopting a fluid‐mud modeling framework, a well‐validated depth/phase‐resolving wave propagation model, based on the Reynolds‐Averaged Navier‐Stokes (RANS) equations, is extended to model cohesive sediment transport. The numerical model consists of a set of governing equations based on the equilibrium Eulerian approach accurate for the fine sediment limit. The numerical model reduces to the clear fluid RANS equations when the sediment concentration approaches zero. Hence, the model is able to calculate continuously and consistently the nonlinear wave propagation, wave boundary layer processes, and fluid‐mud transport without the need to prescribe the mud layer characteristics. Numerical simulations reveal several important physical processes that are critical for understanding the water‐wave dynamics over muddy seabeds: (i) an enhancement of the wave boundary layer thickness due to the presence of the fluid‐mud and rheological stress, which leads to a scaling relation between the enhanced wave boundary‐layer and the fluid‐mud layer and (ii) a direct wave amplitude dissipation due to rheological effects and clear evidences of low‐ and high‐frequency wave attenuation via nonlinear energy transfer.</jats:p>