Numerical characteristics of a coupled river ice and hydrodynamic model

• Published in: Canadian journal of civil engineering Vol. 38; no. 4; pp. 393 - 403
• Main Authors: Nzokou, François, Morse, Brian, Robert, Jean-Loup, Richard, Martin, Tossou, Edmond
• Format: Journal Article
• Language: English
• Published: Ottawa, ON NRC Research Press 01.04.2011; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: Applied sciences; Buildings. Public works; Canada; canaux couverts de glace; Civil engineering; Computation methods. Tables. Charts; Control; dam break; Dam failure; Dam failures; Dams; dynamique des couverts de glace; débâcle; Exact sciences and technology; Finite element analysis; Floating ice; flood wave; Fluid mechanics; Hydraulic constructions; HYDROBEAM; Hydrodynamics; Ice; Ice cover; ice cover dynamics; Ice jams; ice-covered channels; Mathematical models; Methods; Numerical analysis; onde de crue; Open channel flow; Open channels; Prediction (Logic); propagation des vagues; Properties; River banks; River channels; River flow control. Flood control; River ice; Rivers; Structural analysis. Stresses; Wave propagation; Canada; Hydraulics; Rupture; Coverage; Ice break up; Ice; Rivers; Forecast model; Modeling; Characterization; Dam; Flood; Wave propagation; Hydrodynamic model; Numerical simulation
• ISSN: 0315-1468; 1208-6029
• DOI: 10.1139/l11-009

Prediction of dam break surges using numerical tools has been the subject of tremendous research efforts in the past four decades. Powerful numerical tools that can model surge phenomena are readily available on the market. However, for winter conditions, when a river is covered by ice, it becomes difficult or even impossible to predict wave propagation dynamics using these traditional tools. It is therefore important to know what will happen should a dam break or an ice jam release in an ice-covered river. In this study, fully conservative form of the one-dimensional St. Venant equations are derived for water hydrodynamics in variable width trapezoidal channels having a stiff floating ice cover (that is not frozen to the river banks) in addition to the cover’s one-dimensional flexural response (as a beam on an elastic foundation) to incoming waves. A coupled numerical model (HYDROBEAM) using the Galerkin finite element method (FEM) is then developed. The coupling technique in the model uses an iterative computation process to find a simultaneous solution to both flow and ice cover models at each time step. The FEM schemes are evaluated by the simulation of progressive and regressive wave propagations and by the simulation of Stocker’s hypothetical dam break problem. For these simplified cases, analytical solutions exist and are used as references to evaluate the numerical attenuation of the model. The results of the hypothetical dam break simulations are in agreement with the theory. The effects of the spatial and temporal discretization on numerical attenuation of flow dynamics and ice cover peak stresses are evaluated and presented. When used within the recommended guidelines, HYDROBEAM’s performance is more than adequate to simulate (a) open channel flow, (b) rivers with passive (flexible) ice covers or (c) rivers with stiff ice covers that respond as a beam on an elastic foundation.