ASL uses High Performance Computing for Numerical Modeling

ASL has developed processes and systems to manage metocean projects. These include processes and systems for document management, data management, quality management, and health, safety and environment (HSE) systems. We are very proud of our success in collecting metocean data in some of the world’s most challenging oceanographic environments. ASL has developed its own hydrodynamic model and runs publicly available models such as 3-D unstructured Finite Volume Community Ocean Model (FVCOM), Delft3D, and SWAN. ASL has a complete MATLAB- based suite of software for the editing, analyses and visualization of metocean data.

Besides wave modeling for metocean studies, ASL has implemented the SWAN wave model in a number of other coastal projects, including modeling nearshore spectral wave transformation off the west coast of Vancouver Island (Jiang and Fissel, 2003), modeling nearshore spectral wave transformation off the west coast of Africa (Fissel and Jiang, 2004), modeling locally wind-generated waves in the Strait of Georgia and Roberts Bank (Jiang and Fissel, 2005), modeling ocean waves at Victoria's Fisherman’s Wharf (Fissel, et al., 2007), and wave modeling for Victoria International Marina with and without attenuators (Jiang and Fissel, 2008 and 2009; Fissel and Lin 2012; Lin and Fissel 2014).    (read full background)

For coastal planning, looking at sea level rise only based on climate change is insufficient. The tide, storm surge, and wave setup are required to obtain projections of episodic coastal flooding. ASL develops high resolution regional numerical models to evaluate the contributions and complex interactions from four important contributors: (1) regional relative sea level rise due to climate change, (2) storm surge, (3) extreme tides and (4) wave runup. These complex and ever-changing interactions can generate excessive sea level rise, particularly during storms. Using the coupled hydrodynamic and wave model, vulnerable “hot-spots” can be identified. In this demonstration, we quantitatively present the assumed flood inundation in Victoria’s Inner Harbour with the combined effects of extreme events and sea level rise. 

The two animations above represent vector and drifter nearfield numerical models respectively. This numerical modeling research work was done with IOS, DFO to provide preliminary computations of tidal currents in the vicinity of Prince Rupert using a high-resolution grid (Lin et al., 2018) applied through the Finite Volume Community Ocean Model (FVCOM).

Example of numerical modeling showing a one-day animation for SST and surface currents during spring tide (May 23, 2016), Queen Charlotte Strait, BC.

Numerical modeling is a powerful method of visualizing the dynamic behaviour of physical systems. We have developed a three-dimensional computer model (COCIRM-ASL) capable of accurately simulating water circulation in the following environments:

  • Rivers
  • Estuaries
  • Coastal Waters
  • Continental Shelf and Deeper Waters
Our model is founded solidly on the science of fluid dynamics for circulation including such natural forces under the following conditions:

  • Tides
  • Density stratification and buoyancy
  • Wind stress
  • Drag arising from the shoreline and bottom
  • Coriolis
The variable discharge from such engineered works as dams, power stations and sewage treatment stations can readily be included in the model. Our model has been fully calibrated and validated through comparison with extensive data sets in a variety of project environments.

Features and Benefits

Successful calibration and validation of a numerical model against field measurements is an affirmation of our understanding of the natural environment being studied. The power of our computer model "COCIRM-ASL" lies in its ability to predict currents, temperature, salinity and sediment in regions where data is sparse or when extensive data collection is expensive or impractical. COCIRM-ASL can undertake "what if" studies to investigate the impact on river, estuarine or coastal circulation patterns of the placement, for instance:

  • A new dam or plant
  • The effect of changing discharge levels or operational configurations.
  • Coastal engineering structures.
For application of COCIRM-ASL to a new project area, one need only input the geometry of the modeled domain (shoreline, bathymetry, engineering structures), open boundary conditions, and physical properties that are known. The distribution and behaviour of key properties can be readily simulated within the ASL model, including:

  • Tidal currents and circulations
  • Temperature, salinity, and suspended sediment concentration (SSC)
  • Bottom siltation and scour
  • Biological or chemical distributions: plankton abundance, coliform concentrations, oil spills.

Model Description

COCIRM-ASL uses hydrodynamic pressure, sigma-transform, and a variety of turbulence parameters. It solves for the time-dependent, three-dimensional velocities (u, v, w), temperature(T), salinity(s), SSC(c) as well as water surface elevation (Jiang, 1999). It also includes wetting/drying and nested sub-grid schemes, capable of incorporating tidal flats, buoyant jets and relatively small interested areas.

The model boundary conditions consist of the momentum flux (wind stress) at the water surface and the shear stress at the bottom in terms of quadratic or linear law.
At open boundaries, the water levels, velocities or radiation conditions are specified. In the case of discharge from a dam, the resulting currents are oriented to the same direction as the spillway.

A semi-implicit finite difference method is applied in COCIRM-ASL. The numerical solution method has the advantages of a minimum degree of implicitness, good stability (unconditionally stable when one neglects horizontal diffusion) and consistency, and high computational efficiency at a low computational cost. Grid sizes can range from 10 meters to kilometers in size.

ASL Environmental Sciences #1-6703 Rajpur Place V8M 1Z5 Saanichton, BC

Phone: +1 250-656-0177
Email: [email protected]