Application of CFD to Improve Hydrodynamic Modeling to Estimate Local Head Loss Induced by Canal Confluence

摘要

The South Florida Water Management District recently launched the canal capacity study to improve water management in South Florida. Since the authorization of the Central and Southern Florida Project in 1948, urbanization and land development have significantly changed the design conditions. As a result, the original plans are no longer adequate to satisfy the desired level of service. Typically, one- and two-dimensional modeling tools can be adequately used to calibrate, validate, and evaluate canal conveyance capacity based on the geometric information and canal bottom roughness. However, other open channel hydraulic conditions such as canal confluence, channel bend, bridge piers, and other hydraulic structures may also have significant influence on the conveyance capacity. Estimation of localized head losses incurred from these hydraulic conditions requires the use of advanced modeling. In this paper, a three-dimensional CFD model was developed to investigate the effects of a junction on open channel flow characteristics as a case study. CFD model implemented herein is based on solving three-dimensional Reynolds-Averaged Navier-Stokes equations using the κ-ε turbulence model closure. It can provide accurate and detailed flow physics including three-dimensional flow fields, pressures, and water surface elevations. The CFD model was first validated using high quality experimental data of a 90-degree junction flow under two flow conditions. Upon good agreement between model simulation and experimental measurements, the same approach was applied to the C1 canal and C1N canal junction located in the C-1 basin in South Florida. The CFD estimated head loss is intended to be incorporated into existing one/two-dimensional hydrodynamic models as a target function to calibrate the models and optimize the canal capacity for larger scale hydraulic planning problem. This study introduces a feasible approach to apply CFD and hydrodynamic models to resolve canal capacity problems which require very complicated localized hydraulic loss estimation.