Title: Comparison of solutions of Saint-Venant equations by characteristics and finite difference methods for unsteady flow analysis in open channel

Authors: Kaveh Ostad-Ali-Askari; Mohammad Shayannejad; Saeid Eslamian; Bahareh Navabpour

Addresses: Department of Civil Engineering, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran ' Water Engineering Department, College of Agriculture Isfahan University of Technology, Isfahan, Iran ' Water Engineering Department, College of Agriculture Isfahan University of Technology, Isfahan, Iran ' Faculty of Information Technology Engineering, Payam Noor University, Tehran, Iran

Abstract: The unsteady flow can be analysed by Saint-Venant equations. These equations can be solved by characteristics and finite difference methods. The Saint-Venant equations are changed into four complete differential equations in characteristics method and these equations are solved by drawing two characteristics lines. The Saint-Venant equations are changed into set nonlinear equations and are solved using Preissman scheme in finite difference method. This set of equation is changed into linear equation using Newton-Rafson method and can be solved using Sparce method. In this research, the results of the two method were compared and this was shown that: 1) these two methods can draw the surface profiles and flow hydrograph as well; 2) the finite difference method is more accurate than that one; 3) the mesh size in finite difference method can be larger than that one; 4) the difference between two methods are increased by increasing the time and distance.

Keywords: flood routing; dynamic wave; characteristics lines; finite difference; Saint-Venant equations; characteristics method; Newton-Rafson method; Sparce method.

DOI: 10.1504/IJHST.2018.093569

International Journal of Hydrology Science and Technology, 2018 Vol.8 No.3, pp.229 - 243

Received: 02 Mar 2016
Accepted: 23 May 2016
Published online: 30 Jul 2018 *

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