The large number of two-dimensional (2D) depth-averaged flow models currently available (e.g. Mike 21, River2D, Telemac-2D, SRH-2D, CCHE2D, FLO-2D, RiverFLO-2D, RMA2, FESWMS, ADH, TUFLOW, Delft3D, SToRM, FaSTMECH, RIC-Nays, Iber, Basement, etc.) attest to the fact that 2D flow modelling is now a common and well-established practice in river engineering. Despite their apparent differences, all 2D models share some basic common features that all numerical modellers should know and understand. Unfortunately, the classical open-channel flow courses taught at undergrad level do not provide engineers which such knowledge. This seminar is intended to bridge that knowledge gap.
The first part of the seminar provides the basic –but necessary- understanding of hydrodynamic flow models in general; while the second part focuses on 2D flow models and provides hands-on training using the simple, yet powerful and widely-tested River2D flow model.
Following the adage ‘the modeller is more important than the model’, the seminar intends to provide current or prospective hydrodynamic modellers with the basic practical knowledge needed to better understand and make use of numerical modelling tools, regardless of the specific software used.
Additionally, and in order to demonstrate how to setup and apply a 2D flow model, the seminar also provides basic hands-on training on the popular Canadian 2D flow model River2D.
Knowledge of undergraduate level open-channel flow hydraulics. Previous experience with 1D flow models such as HEC-RAS would be helpful; but not necessary.
PART 1. INTRODUCTION
Models. Basic concepts. Physical, mathematical and numerical models.
Numerical models. Numerical solution; computational domain; boundary conditions; initial conditions. Computational variables and visualization. Input data. Computers and Moore’s law.
Classical Hydraulics. Equations, from Navier-Stokes to Bernoulli. Limitations and need for numerical models.
Numerical Approximations. Continuous vs. discrete systems. Structured and unstructured meshes. Discretization methods (finite differences, finite elements, finite volumes). Explicit and implicit methods, the CFL number.
Dimensions: 1D, 2D and 3D flow models. Bathymetric and topographic data requirements. When are 2D models needed?
Turbulence: Energy losses, friction, mixing. Turbulence fluctuations and shear velocity. Eddy viscosity and turbulence modelling.
PART 2. 2D FLOW MODELS
The shallow water approximation.
The standard 2D flow problem and what differentiates various 2D models: wetting and drying, unsteady flow, mesh size, super-critical flow, dam-breaks, parallelization, tailored sub-models (e.g. ice cover, fish habitat, water quality, sediment transport, non-Newtonian fluids, etc.).
Example applications: bridge hydraulics, river training works, flooding, desanders.
River2D tutorial: bed file and mesh development. Flow simulations. Visualization and data extraction.
Model calibration and verification. Sensitivity analysis.
Unique features of the course
The course is a synthesis of the experience gained using several different 2D flow models in many different practical river engineering applications around the world. As such, it selectively provides relevant background knowledge that has wide-range implications for practical river flow modelling.
Engineers interested in expanding their open-channel river flow knowledge and skills beyond the basic 1D flow hydraulics learned in undergrad school. Prospective users of 2D flow models. Junior engineers currently using 2D models.
Jose (Pepe) Vasquez, P.Eng., Ph.D., Associate – Northwest Hydraulic Consultants Ltd.
Pepe is a numerical modelling expert with over 20 years of consulting and research experience in engineering projects relating to water resources, hydraulics and river engineering in North America, South America and Asia. Pepe’s main fields of expertise are numerical modeling and river engineering. As part of his doctoral research at UBC, Pepe developed the 2D Finite Element model River2D-MORphology to compute bed level changes in rivers caused by bedload sediment transport. Pepe has considerable experience applying 2D flow models in large river systems. Locally in BC, he has conducted 2D flow modelling for assessing the flow hydraulics of the Golden Ears Bridge, Port Mann Bridge and Pattullo Bridge in the Fraser River; as well as the Pitt River Bridge in the Pitt River. In Bangladesh, he has applied 2D models to the river training works of the proposed 6.2 km long Padma River Bridge, designed for a discharge of 150,000 m3/s; as well as the river bank protections for the Brahmaputra/Jamuna River. In Brazil, he modelled the reservoir of an 11,000 MW hydroelectric project, as well as the river flow near fluvial ports in the Paraguay and Amazon Rivers. Over the years, Pepe has trained dozens of junior engineers in the use of 2D flow models.