Modeling Turbulent Mixing and Sand Distribution in the Bottom Boundary Layer
by Rafik Absi, (EBI, 32 Bd du Port, 95094 CergyPontoise cedex, France Email: r.absi@ebiedu.com) Section: Suspended Sediment, pp. 114, (doi: http://dx.doi.org/10.1061/40855(214)99)
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Document type: 
Conference Proceeding Paper 
Part of: 
Coastal Dynamics 2005: State of the Practice 
Abstract: 
For the calculation of turbulent mixing in the bottom boundary layer, we present simple analytical tools for the mixing velocity w_{m} and the mixing length l_{m}. Based on observations of turbulence intensity measurements, the mixing velocity w_{m} is represented by an exponential function decaying with z. We suggest two theoretical functions for the mixing length, a first l_{m1} obtained from the kequation written as a constant modeled fluctuating kinetic energy flux and a second l_{m2} based on von Kármán’s similarity hypothesis. These analytical tools were used in the finitemixinglength model of Nielsen and Teakle. The modeling of timemean sediment concentration profiles C(z) over wave ripples shows that at the opposite of the second equation l_{m2} which increases the upward convexity of C(z), the first equation l_{m1} increases the upward concavity of C(z) and is able to reproduce the shape of the measured concentrations for coarse sand. 
