Turbulence Modeling of Surface Water Flow and Transport: Part I

This paper is the first of a five part series documenting the structure of turbulence models, their use in various classes of surface water models, the considerations required in selecting or building a turbulence model‐based code, and an evaluation of the impact of such models on surface water modeling. Surface water models are considered in these papers with both hydraulic engineering and environmental hydraulics applications in mind. In the first paper the general model equations for free surface flow and transport are stated for the case of two‐dimensional vertically averaged and two‐dimensional areally averaged situations as well as the general three‐dimensional case. Terms requiring closure are defined and the basic eddy viscosity and diffusivity concept is presented. The various classes of turbulence models are defined and a very brief discussion of constant and mixing length dependent viscosity ensues. The paper concludes with a presentation of the one‐equation and general two‐equation k‐ε turbulence model for multidimensional flows. The constants used in the two‐equation model are summarized and their universality is discussed.