Author(s): Heredia Marcelo; Toorman Erik; Berlamont Jean
Linked Author(s):
Keywords: Turbulence; Two-layer models; Roughness; Free surface flow
Abstract: Two-layer turbulence models are calibrated for flows with smooth bottoms. Considering that most of the flow processes are over rough walls, it is necessary to search for models which account for roughness. Two such models, based on the classic two-layer turbulence models, are reported in literature. They are the models of Patel & Yoon (1995) and the model of Durbin et al. (2001). The main element to assess the models is the roughness characterization function DB of the log-law equation, which corresponds to the shift of the vertical velocity profile due to roughness. These models are based on the use of height displacements in vertical coordinates, modifications of the eddy viscosity equations and boundary conditions of the kinetic energy. These models are implemented in the research code FENST-2D and tested. The model of Durbin et al. (2001) produces better results for the variation of the DB function; this was confirmed by the simulation of the experimental testcases obtained from literature. However, there is still some uncertainty about the evolution of the vertical profiles of kinetic energy and its dissipation rate due to roughness. Therefore, it is necessary to do more research and measurements in the near-wall area to determine the influence of roughness to develop improved two-layer turbulence models.
Year: 2007