Abstract

The Study investigates the use of Computational Fluid Dynamics (CFD) to analyze the mean characteristics of curvilinear flows in selected hydraulic structures. Three chosen turbulence models are associated with the Volume of Fluid (VOF) scheme to predict the characteristics of the mean flow. Many hydraulic structures in engineering practice involve highly curvilinear flows. Five typical hydraulic structures commonly used for flow regulation or flow measurement are considered in the present study; cut-throat flumes, lateral weirs, sharp-crested weirs, circular spillways, and siphon spillways. Velocity distributions, pressure distributions, water surface profiles, secondary flows, and discharge coefficients are the mean characteristics of flows that are studied. Presently, computing methods and high speed computers are strong tools for engineers. With the help of a properly validated numerical model, one can avoid the time consuming and expensive experimental tests based on the physical models to obtain the characteristics of highly curvilinear flows encountered in hydraulic practices. This is based on the fact that unlike physical models, it is far simpler to apply changing boundary conditions and flow parameters to a solved numerical model and obtain a flow characteristics for hydraulic structures associated with highly curvilinear flows. The flows in hydraulic structures are turbulent. Hence, one needs to solve numerically the continuity equation and momentum equations, including turbulent stresses, as the governing equations of turbulent flows. Because the above mentioned flows are generally complex and highly curvilinear, the transport equations are needed to model the turbulent stresses in the momentum equations. In the present study, three Reynolds-Averaged Navier-Stokes (RANS) schemes are used to simulate the turbulent flows. Specifically, the Reynolds stress model (RSM), the Standard k-[varepsilon] model, and the RNG k-[varepsilon] model were used in the present study. Further, the VOF scheme is adopted to find the shape of free surface profiles