Fluid mud in the wave-dominated environment revisited

Generation of fluid mud by short period water waves is revisited following previously reported analytic work of the authors. Liquefaction of a soft cohesive mud bed due to wave-induced pressure loading is considered to occur when the effective submerged weight of the particle or floc is exceeded by the upward inertial force due to bed oscillation. Bed dynamics, characterized by a uniaxial extensional-Voigt viscoelastic solid response, is modeled as a spring-dashpot-mass analog for obtaining fluid mud layer thickness at equilibrium under sustained wave motion. Model results are compared with data obtained in wave flumes using weakly cohesive muds. Order of magnitude agreement between theory and data suggests that shear rheometry can be used to determine the appropriate constitutive relationship required to calculate fluid mud thickness. It is shown that the model provides reasonable estimates of fluid mud thickness in Lake Okeechobee in south-central Florida. A noteworthy feature of the method is that mud properties are described by easily measurable parameters including density and rheological constants, without the need to specify mud composition.