CFD software applications for transcritical free surface flow

Abstract:

Open flow channel is very common in engineering applications. Traditional approaches solve shallow-water flow equations, known as Saint-Venant equations, when one or two dimension solutions can be adequate for obtaining most of the important flow characteristics. However, complex situations can require solving Navier-Stokes equations. The arrival of high performance computers and commercial software packages offers new possibilities in the field of numerical hydraulics. However, commercial software packages should be tested on some specific cases; so that these can be used with confidence. In this paper we solve several cases of free surface flow that consider subcritical, supercritical, critical, oscillatory depth profiles and hydraulic jumps using a commercial package, CFX™. Most of these cases are proposed as benchmark solutions for non-prismatic cross section, non-uniform bed slope and transition between subcritical and supercritical flow. Other cases as Hydraulic jump consist of experimental data of hydraulics jumps for incident flow with Froude numbers up to 4.23. Both types of cases allow us to perform the verification and validation of the commercial package used. Results obtained with CFX™ show excellent agreement with analytical solutions, for subcritical, supercritical, transitional and hydraulic jump cases. Special care with grid selection and entrance boundary condition is crucial to simulate with accuracy these types of flows. In particular, when a proper structured mesh is used, quality results are highly improved. Finally, results show to be insensitive to entrance turbulence conditions. Copyright © 2009 by ASME.

Año de publicación:

2009

Keywords:

Fuente:

scopus