Velocity lag between particle and liquid in sediment-laden open channel turbulent flow

This study focuses on the prediction of velocity lag between particle and liquid in sediment-laden open channel turbulent flow. From theoretical point of view, we formulate a mathematical model of velocity lag based on hindered drag force on particle, impact shear stress, viscous shear stress and turbulent shear stress which are derived from the viewpoint of turbulence, particle-liquid interaction, particle-particle interaction and random dispersion of suspended sediment owing to these interactions. No estimation of empirical parameter is required for calculating velocity lag from the resultant model. The profile of velocity lag obtained is a function of particle diameter, mass density of sediment particle, shear velocity and vertical height from channel bed. The model also explains real phenomenological characteristics of velocity lag caused by the interaction between particle and liquid during turbulent flow. Our model well agrees with a wide range of twenty-two experimental runs collected from published literature. In addition, error analysis proves the superior prediction accuracy of our model in comparison to other existing models of velocity lag.