Reinvestigating the Parabolic-Shaped Eddy Viscosity Profile for Free Surface Flows

The flow in rivers is turbulent. main parameter related to turbulence the eddy viscosity, which used model a turbulent and involved determination of both velocities sediment concentrations. A well-known largely vertical distribution viscosity free surface flows (open channels rivers) given by parabolic profile that based on logarithmic velocity assumption valid therefore only log-law layer. It was improved thanks log-wake law profile. These two viscosities are obtained from profiles, shortcoming empirical Coles’ parameter. more rigorous reliable analytical needed. In this study, we present models concepts length scales, exponentially decreasing kinetic energy (TKE) function mixing length, namely, (1) exponential-type (2) an extension von Karman’s similarity hypothesis. second Re*-independent, while first Re*-dependent (where Re* friction Reynolds number). proposed were validated through computation resolution momentum equation comparisons experimental data. With additional correction damping effect near surface, similar log-wake-modified but with different values parameter, i.e., ?=0.2 for ?=0.15 model. those found open-channel experiments. This provides explanation about accuracy these outer part flows. For large (Re* > 2000), becomes independent, coefficients reach asymptotic values. Finally, data viscosity.