Discussion on the Vertical Distribution Formula of the Velocity on the Stoss Side over Sandwave

Complex hydrodynamics is essentially the superposition of dynamic changes of flow, sediment and movable boundary. The bedforms including sand ripples and sand dunes are induced by the water flow. Conversely, the changes of bottom morphology would affect the bed roughness, sediment transport and kinematic characteristics of water flow. It would own great significance to study the morphological and kinematic characteristics of sand waves, and analyse the influence of different hydrodynamic conditions and sand wave topographies on the flow turbulent structure. According to the numerical calculation and theorical analysis on the classical experiment of asymmetric sandwave, the structure characteristics of velocity profile over sandwave are analyzed further and the variation law of flow velocity along the direction of propagation. In order to improve the computing accurary of velocity profile on the stoss side over sandwave, the classical velocity decomposition method are discussed deeply. Meanwhile, the expression of velocity deviation angular function, a new concept, is put forward with the distribution law of flow velocity along the sandwave. The velocity vector is transformed by establishing the sub coordinate system, and the formula of flow velocity profile for the the stoss side over sandwave is derived. Experimental results of classical water flow velocity on the stoss side are used to verify the deduced formulas. The results show that compared with other formulas, the proposed formulas own better accuracy and could more reasonably express the vertical velocity distribution along the water flow.