Numerical and experimental analyses of open channel flows behind control structures

Because the governing equations of the fluid motion contain the terms of viscosity and turbulence, it is generally difficult to obtain the analytical solutions of these equations except the flow problems that have simple geometric boundaries. Different numerical methods are used to obtain approximate solutions of such problems. In this study, velocity measurements for a flow of triangular broad-crested weir are taken using PIV in a laboratory channel. Using the ANSYS package program, based on the finite element method, the numerical solutions for the Laplace and transport equations are obtain to compare with experimental velocities. The free surface profiles on the rectangular and triangular broad-crested weirs modeled in a laboratory channel are theoretically obtained with the volume of fluid (VOF) analysis and compared with the experimental free surfaces. Key Words: free surface flow, broad-crested weir, particle image velocimetry (PIV), volume of fluid method (VOF), potential flow.