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Coastal Engineering
Physical and Numerical Modelling
The Canadian Hydraulics Centre of the National Research Council is Canada’s largest coastal and hydraulic engineering laboratory. It is equipped with some of the world’s most sophisticated technology for the generation of two- and three-dimensional waves for the physical modelling of coastal engineering problems. Many problems can also be investigated and solved using numerical models. The Centre is uniquely equipped to develop, test and validate numerical models through comparison to large-scale physical models and to field measurements. However, numerous problems remain where physical modelling stands unchallenged as the preferred approach. Quite often the Centre will undertake studies where both numerical and physical models are used in order to obtain the most reliable answers in the most efficient and cost-effective manner.
Wave Climates
In open coastal areas where the processes of wind-wave growth, shoaling and refraction are dominant, CHC uses a variety of models including spectral wind-wave models based on energy and kinematic conservation equations to predict local wave climates. These computer models consider the effects of local wave generation due to wind, shoaling and refraction due to varying water depth, energy dissipation due to wave breaking, and the cross-spectral transfer of energy due to non-linear wave-wave interactions. Predicted wave conditions can be propagated either numerically or using physical models to shoreline areas of interest.
Hydrodynamics of Coastal Areas, Rivers, Lakes and Estuaries
CHC models hydrodynamics and circulation either physically or numerically, for the simulation of water levels and currents in lakes, rivers, estuaries and coastal areas. Where necessary, numerical simulations can also include salinity and temperature. By simulating complex hydrodynamic processes interacting with various civil engineering works options, cost effective and reliable solutions can be found. CHC has a variety of one-, two- and three-dimensional hydrodynamic numerical models available and can choose the best model for the area being studied. Besides providing basic hydrodynamic information affecting a region under investigation, these models can be linked with transport models to tackle sediment and environmental water quality problems.
Wave Agitation in Harbours and Marinas
CHC has extensive experience with harbours and marinas involving problems with wave agitation, ship moorings, the design of breakwater configurations, etc. To model these problems and their solutions, nearshore wave climates at a specific site must often be estimated from wind data or wave data measured at distant locations. Offshore wave characteristics are then transformed to nearshore sites by taking into account the effects of the seabed topography, the presence of currents, wave breaking, local wind generation and diffraction into ports and harbours.
Physical modelling provides information on wave activity at nearshore sites and the wave agitation inside marinas or harbours. Numerical models are also available to generate realistic sea states resulting from wind, from ship waves, or both. Numerical studies are often conducted in combination with physical models that can provide additional verification and calibration, and refinement in three-dimensionally complex areas.
The model WaveSim was developed by CHC to simulate the transformation of irregular multidirectional waves in water of varying depth due to the effects of shoaling, refraction, diffraction, reflection, non-linear wave-wave interactions, breaking, and wave-induced currents. This model can also simulate the generation of infra-gravity waves by groups of short waves in shallow water. The long period energy may be amplified in a harbour if one of the natural modes of oscillation of the harbour is excited.
Erosion and Deposition of Sediments
CHC has many years of experience solving erosion and sedimentation problems using physical and numerical models. For example, estimates on annual maintenance dredging can be provided for ports and navigation channels or the fate of dredge spoils can be predicted. Also, the erosion of shorelines and cliffs, and the resulting transportation and deposition of materials can be studied. CHC has numerical sediment models to simulate the erosion and deposition of two phase sediments — cohesive mud, non-cohesive sand and mixtures of the two. Models can be run dynamically coupled to a hydrodynamic model where the changes in the bed would affect the hydrodynamics. Besides the effect of currents, wave agitation effects on the sediment can be accounted for using wave disturbance maps supplied from a wave agitation model.
Beach Erosion and Shoreline Protection
Beach evolution modelling is used to study the long-term evolution of shorelines. By combining the prediction of tidal flows along a coast obtained from a hydrodynamic model and the prediction of wave induced flows obtained from a wave agitation model with a shoreline evolution model, estimates of littoral drift, shoreline erosion and deposition can be obtained. CHC has several models that can be used to predict, for example, the changes in a shoreline adjacent to harbour developments.
Ship Wake Modelling
CHC's WAKE2D is a numerical model that is used to simulate the wave pattern generated by multiple ships and their impacts on shorelines and harbour structures. Most previous studies of ship waves in shallow water use empirical curves to predict the amplitude, period and direction of ship waves at a given distance from the ship's track. The ship waves are then assumed to be regular waves and input into wave transformation models. Such an approach, however, ignores the transient and radiative nature of ship waves (e.g. the decrease in amplitude of ship waves as they radiate further away from the ship). With the CHC model, waves generated by moving ships are simulated directly in a time dependent, wave transformation model. The radiation, refraction and reflection of ship waves are all treated in a consistent manner. Wind generated waves can also be superimposed to simulate the interaction of ship waves with wind waves.
Applications also include the study of shoreline erosion in rivers and shipping channels.
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