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Accurate flow ratings at water-control structures are essential for water-resource management. This paper presents an approach to obtain numerically generated data using computational fluid dynamics (CFD) to complement field measurements needed to improve spillway flow-rating formulas. The procedure to generate CFD flow data described herein is based on solving Reynolds-Averaged Navier-Stokes equations using the κ-ε turbulence closure model with the free surface resolved by the volume of fluid (VOF) method. The steps for setting the computational domain, generating the mesh, selecting the boundary conditions, and choosing a convergence criteria for the simulations are discussed. The turbulence closure model and VOF method for the present application are verified with data from laboratory measurements of submerged jet flow below a gate and in a sharp open-channel bend. CFD flow data generation is validated with laboratory and field measurements for gated ogee spillways in south Florida. The results presented here demonstrate that CFD is a plausible alternative to complement data measured at prototype structures and reduced-scale models for the purpose of calibration and validation of rating formulas used for real-time flow monitoring at prototype water-control structures. [ABSTRACT FROM AUTHOR]

Traditionally, flow-rating formulas for hydraulic structures are calibrated and validated with data comprising field measurements of discharge, water stages, and operational settings monitored in near real time. Lack of sufficient field measurements that include all flow types and cover the full operational ranges has been a major constraint in developing reliable flow ratings for prototype hydraulic structures. A companion paper introduced a plausible method that relies on computational fluid dynamics (CFD) simulations to generate accurate flow data that complements field measurements for flow rating analysis. In this paper, a general framework for applying CFD in flow rating is proposed, which includes planning of CFD simulations, assessing CFD flow data, and improving existing flow ratings using a hybrid data set of field-measured and CFD-simulated flows. Finally, two case studies of flow rating for spillways and weirs carried out to demonstrate the proposed framework are presented. Results show that the proposed framework offers a cost-effective approach that provides robust, comprehensive flow rating formulas that yield reliable flow estimates for the operation of hydraulic structures under multiple water-resource management constraints. [ABSTRACT FROM AUTHOR]