抄録
Derivation processes of a depth averaged model of open channel flows over an arbitrary 3-D surface were shown in a generalized curvilinear coordinate system in detail. It is necessary to develop the model to design hydraulic facilities such as a water slider, a manmade-cascade, etc. The ξ-η axes are set on an surface of objectives as the body fitted coordinates and the ξ axis is determined to be at right angles to an surface. The depth averaged continuity and momentum equations are derived by integrating the equations in the body fitted coordinates from the body surface to water surface. The analysis of flow over a circle cylinder is shown as the simple application of model.
