Bem Numeric Simulation Of Spillway Flows With Discontinuous Linear Elements

Abstract

The study of gravity free surface flows presents difficulties as the nonlinearity of
the dynamic boundary condition in the free surface, and also the fact that the location of this
surface is not known a priori. Traditionally, this phenomenon has been investigated by
physical models, but the progress of computer science and numeric methods has been
allowing more and more the successful use of mathematical models to simulate this type of
flow. This work presents a boundary element method (BEM) numeric simulation of spillway
flows with discontinuous linear elements. The solution procedure involves an iterative process
in the determination of the free surface. The Newton-Raphson method is adopted together
with the use of pseudo-nodes on the free surface and an empiric step factor (or damping
factor) which controls the stability and the rate of convergence. An example of WES standard
spillway shape is presented. The obtained results are compared with experimental data and
they check the efficiency and good precision of the adopted method.