Author(s): Takahiro Itoh; Kuniaki Miyamoto; Shinji Egashira; Kaushal Raj Sharma
Linked Author(s): Takahiro Itoh
Keywords: Reynolds similarity; Froude similarity; Constitutive equation; Hydraulic model test
Abstract: Hydraulic model tests are a common method to investigate the behaviour of flood flows and debris flows such as the inundation process and the effects of countermeasure facilities, and such tests should satisfy appropriate similarity laws, e. g., Reynolds, Froude, Richardson, Bingham. On the other hand, many numerical simulations have been also conducted based on the governing equations including constitutive equations. In the case of debris flow, it is well known that sediment-water mixture dose not behave as a Newtonian fluid, and, therefore, the constitutive equations for debris flows have been a topic of investigation. If the flows could be well explained using a set of constitutive equations, the flows could be considered as laminar, and the flow should satisfy Reynolds similarity instead of Froude similarity. Based on the above two considerations, it is questionable whether debris flows follow Froude similarity, even though hydraulic model tests of debris flows have been conducted based on Froude similarity. In the present study, the similarity of debris flow, including important non-dimensional parameters, will be discussed based on the governing equations and the constitutive equations. It is found that Reynolds similarity of debris flow is formulated as the same style as Froude similarity, and non-dimensional important parameters to satisfy the similarity can be also found. These our assertions are confirmed using numerical simulations of debris flows.
Year: 2007