Author(s): Bhoomi R. Andharia, Prem Lal Patel, Vivek L. Manekar, Prakash D. Porey
Linked Author(s): Bhoomi R. Andharia
Keywords: Numerical model, aggradation, noncohesive sediment mixture, active bed layer, fractional sediment transport
Abstract: In present study, a semi-coupled numerical model, based on one dimensional de Saint-Venant equations along with sediment continuity equation, is developed for prediction of bed levels in case of graded noncohesive sediments in aggrading alluvial channels. One dimensional, unsteady flow equations and sediment continuity equations are solved using �shock-capturing�, second order accurate, explicit MacCormack finite difference scheme while considering upstream and downstream boundary conditions in the channel. Series of experimental investigations have been undertaken for measurements of bed and water levels in an aggrading channel due to overloading of nonuniform sediments, extracted from the bed of Tapi River at Surat City, at sediment transport flume installed in Advanced Hydraulics Laboratory of SVNIT, Surat, India. A strong coupling between the water flow and sediment variables has been achieved. The sediment continuity equation is used for the each size class to compute the volume of each size class after each time step at any computational node in the computational grid. The fractional bed and suspended load transport capacities for different size fractions have been computed using fractional transport laws for nonuniform sediments using active bed layer concept to consider the interaction and exchange of sediment and water flow near the mixing layer. The developed numerical model for bed level variation of nonuniform sediment bed has been compared with numerical model for uniform sediment bed while using the 7 test runs having total 26 sets of data collected in the laboratory. The performances of the model have been found better while considering the sediment nonuniformity in the model. The performance of developed numerical model has been satisfactorily verified with other independent experimental data on non-uniform sediment bed
Year: 2017