Modelling coastal discharge
The model was adapted to dynamically couple a turbulent plume model with a regional ocean circulation model
Hawaii, USA-headquartered Makai Ocean Engineering is expanding its environmental and coastal modelling services for clients who discharge into, or withdraw from, the world’s oceans, lakes, and reservoirs.
The adapted M-EFDC model is a state-of-the-art hydrodynamic and water quality model used to simulate aquatic systems in up to three dimensions and time. The modelling results are used in the design, planning, and permitting process for the intake or discharge of a variety of facilities, including desalination, seawater cooling systems including once through cooling systems, LNG processing plants, petroleum refineries, traditional thermoelectric power plants, pulp and paper mills, chemical manufacturing plants, food processing plants, and metal manufacturing plants. The M-EFDC suite can model flows across a wide range of sizes and time-scales. This enables developers to understand the physical, chemical, and biological impacts and decide between design variations in the water system. For example, M-EFDC can help with the site selection for the water intake or discharge pipes, model thermal and chemical plume dispersion, and enable regional nutrient and biological studies.
Under DARPA and Department of Energy funding, (US agencies), the M-EFDC model was originally developed to predict the physical, chemical, and biological impacts around offshore Ocean Thermal Energy Conversion (OTEC) plants in Hawaii. The model was adapted to dynamically couple a turbulent plume model with a regional ocean circulation model and predict both near-field mixing and far-field dispersion of discharge flows; a critical enhancement for accurately resolving larger scale discharge flows. The model integrated regional circulation from tides and atmospheric conditions, nutrient cycles, and phytoplankton population dynamics. Results were shown to reproduce the historical 20 year observational dataset collected by the Hawaii Ocean Time Series. Watch a visualisation of the physical/chemical plume results using the M-EFDC model at https://youtu.be/1hmAOVCvgc0
Most recently, Makai developed a front-end initialisation tool for the M-EFDC model to satisfy a broader range of client needs more efficiently. The front-end tool automates nesting of the M-EFDC grids within 3rd party regional ocean or coastal models (e.g. ROMS or HYCOM), import of local tidal conditions from the TPXO global database, or inclusion of user defined time series based on site measurements or known flow conditions. More generally, the model can be forced with regional flows, tidal flows, atmospheric forcing, and river or terrestrial sources, enabling the simulation of flows that vary with space and time across complex seafloor terrain. In addition, the tool enables quick and automated setup of simpler hydrodynamic studies for project planning.
By Jake Frith
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