Bed form geometry and friction factor of flow over a bed covered by dunes.

An in-depth analysis of existing, methods for prediction of dune steepness is presented. In particular, the expressions by Yalin and Scheuerlein (1988) and van Rijn (1982) are investigated. It is revealed that the expressions by these authors, which were developed on the basis mainly of laboratory data, do not adequately reflect the behavior of dunes occurring in rivers (characterized by large values of relative flow depth). A new expression for dune steepness is introduced with the intention of extending the applicability of previous expressions to river data. This expression is a generalization of the expression by Yalin and Scheuerlein (1988). The validity of the dune steepness expression introduced in this thesis is tested by using it in the determination of the friction factor. It is shown that the use of the dune steepness expression introduced herein yields an improved prediction of the friction factor. Source: Masters Abstracts International, Volume: 39-02, page: 0557. Adviser: Ana M. A. F. da Silva. Thesis (M.A.Sc.)--University of Windsor (Canada), 1999