Author(s): Hidekazu Shirai; Takashi Hosoda; Naoya Kanazawa
Linked Author(s): Hidekazu Shirai, Takashi Hosoda
Keywords: Roll waves; Unsteady open channel flow; Shallow water equations
Abstract: Roll waves have been studied experimentally and theoretically to clarify their hydraulic characteristics, especially wave profiles. According to Dressler (1949) mathematical theory, which is derived from shallow water equations by assuming that Boussinesq’s coefficient is 1. 0, the wave profiles are determined by discharge, channel slope and wave celerity. Later, Iwagaki& Iwasa (1955) extended this theory to deal with both turbulence and laminar water flows by Boussinesq’s coefficient equal to 1. 05-1. 2. However, using this extended theory, wave profiles are uniquely determined without relation to wave celerity. In this study, the derivation of the theory is reviewed and compared with Dressler’s theory, in order to understand the origin of this difference from Dressler’s theory. The comparison of Dressler’s theory shows that the wave profiles presented by Iwagaki& Iwasa’s theory can be obtained under the limited situation. Numerical simulation of roll waves are also conducted. Finally, it is found that wave profiles are not unique and these roll waves have various wavelength and wave height in numerical results regardless of Boussinesq’s coefficient.
Year: 2015