Open‐Channel Flow Algorithm in Newton‐Raphson Form

Abstract

The standard step method is one of the most widely accepted procedures for computing open‐channel water surface profiles. Conventional computer models that use the standard step method often have cumbersome data requirements for routine drainage analyses. An algorithm has been developed that executes the standard step method in prismatic open channels. This algorithm, presented in Newton‐Raphson form, is suitable for subcritical, supercritical, critical, adverse, and horizontal flow regimes. Transition channel sections having linearly variable bottom widths are easily accommodated. Numerical solution of the standard step equations, without using look‐up tables and interpolation procedures, results in fast execution times. A steady flow computer program that uses the algorithm has been developed to perform some “smart” checking of hydraulic profile logic and to facilitate simple data entry. The program is available to interested persons free of charge, upon receipt of a self‐addressed stamped envelope, disk mailer, and diskette.