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201959 1CoastalOcean ModellingNumerical Mod.docx
- 1. 2019/5/9 1 Coastal/Ocean Modelling Numerical Models 22019/5/9 Processes and science knowledge Projects & engineering applications Numerical models training Continuous parameter is described in a number of discrete points Accuracy of description depends on the number of points, i.e. the resolution of the numerical grid
- 2. MIKE Powered by DHI ◼ https://www.mikepoweredbydhi.com/ ◼ MIKE Powered by DHI’s software products have been used in water environments all over the world to solve tough and complex challenges in areas such as oceans and coastlines, rivers and reservoirs, ecology, groundwater, water distribution, wastewater and many more. ◼ Its data management, decision support and operational forecasting software suite traverses all the areas of applications. ◼ Software MIKE 21 can be downloaded at https://www.mikepoweredbydhi.com/download/mike- 2017?utm_source=landingpage&utm_medium=website&utm_ca mpaign=mpbd-rel-2017 32019/5/9 https://www.mikepoweredbydhi.com/ WATER RESOURCES ◼ MIKE FLOOD
- 3. ◼ MIKE HYDRO River ◼ MIKE SHE ◼ MIKE HYDRO Basin ◼ MIKE 21C ◼ MIKE OPERATIONS COAST AND SEA ◼ MIKE 21 ◼ MIKE 3 ◼ LITPACK ◼ MIKE FLOOD ◼ MIKE Animator Plus ◼ ABM Lab ◼ MIKE ECO Lab ◼ MIKE C-MAP ◼ MIKE OPERATIONS 42019/5/9 CITIES ◼ MIKE URBAN ◼ WEST
- 4. ◼ MIKE FLOOD ◼ MIKE OPERATIONS GROUNDWATER AND POROUS MEDIA ◼ FEFLOW https://www.mikepoweredbydhi.com/products/mike-flood https://www.mikepoweredbydhi.com/products/mike-hydro-river https://www.mikepoweredbydhi.com/products/mike-she https://www.mikepoweredbydhi.com/products/mike-hydro-basin https://www.mikepoweredbydhi.com/products/mike-21c https://www.mikepoweredbydhi.com/products/mike-operations https://www.mikepoweredbydhi.com/products/mike-21 https://www.mikepoweredbydhi.com/products/mike-3 https://www.mikepoweredbydhi.com/products/litpack https://www.mikepoweredbydhi.com/products/mike-flood https://www.mikepoweredbydhi.com/products/mike-animator https://www.mikepoweredbydhi.com/products/abm-lab https://www.mikepoweredbydhi.com/products/mike-eco-lab https://www.mikepoweredbydhi.com/products/mike-c-map https://www.mikepoweredbydhi.com/products/mike-operations https://www.mikepoweredbydhi.com/products/mike-urban https://www.mikepoweredbydhi.com/products/west https://www.mikepoweredbydhi.com/products/mike-flood https://www.mikepoweredbydhi.com/products/mike-operations https://www.mikepoweredbydhi.com/products/feflow Port of Brisbane Pty Ltd (PBPL), Australia, considered expanding its navigational channel to
- 5. enable deeper draft vessels to pass through its waters. In order to carry out the planning effectively, the client implemented the Port Expansion Solution , which uses an integrated approach to reduce costs significantly, while ensuring safe working conditions at the port. This solution has paved the way to providing cost-efficient port expansion planning in the future. 52019/5/9 https://www.mikepoweredbydhi.com/global/references/apac/ove rview/port-of-brisbane https://www.dhigroup.com/marine-water/port-expansion- solution?utm_source=casestory&utm_medium=website https://www.mikepoweredbydhi.com/global/references/apac/ove rview/port-of-brisbane
- 6. MIKE 21 SW - SPECTRAL WAVES ◼ Wave modelling is indispensable in a large number of contexts related to activities offshore and in coastal regions. In the design of structures, accurate assessment of wave conditions is of major importance. Sediment transport is also to a large extent caused by wave induced currents. Thus, knowledge of wave climate is necessary in order to design solutions to challenges, such as coastal erosion or harbour sedimentation. ◼ The spectral wave module, MIKE 21 SW, is a state-of-the-art spectral wind-wave model. The module enables you to simulate
- 7. growth, decay and transformation of wind-generated waves and swells in offshore and coastal areas. The model works in flexible meshes, which makes it particularly well-suited to handle variable spatial resolution in the model domain. The model includes the main physical phenomena, for example wave-wave interaction, white- capping, dissipation, refraction and shoaling. 62019/5/9 Key equation to solve: ◼ The evolution of the wave spectrum is described by the spectral action balance equation:
- 8. • coordinates: longitude, λ; latitude, ϕ; wave direction, θ; • relative angular frequency, σ=2pf; • action density spectrum, N(σ, θ); • propagation velocities in λ, ϕ, θ and σ space, cλ, cϕ, cθ and cσ; • S - source term in terms of energy density representing effects of generation, dissipation and nonlinear wave-wave interactions. 72019/5/9 t
- 9. N = + + + +
- 10. Example: Fetch-limited Wave Growth in a Lake The purpose of this simple application is to study fetch-limited wind- wave growth in a 40 km long and 40 km wide lake having a constant water depth of 15 m. The fully spectral formulation is used. The results can readily be compared to well-known fetch-limited growth relationships in the literature. The wind is blowing from West (270 °N) for 15 hours. The wind speed is constant U10= 13 m/s. Estimate the wave charateristic parameters.
- 11. 8 westly wind U10 How to set up the model using MIKE 21 SW? 92019/5/9 The On-line Help can be activated in several ways, depending on the user’s requirement: ◼ F1-key seeking help on a specific activated dialog: To access the help associated with a specific dialog page, press the F1-key on the keyboard after opening
- 12. the editor and activating the specific property page. ◼ Open the On-line Help system for browsing manually after a specific help page: Open the On-line Help system by selecting “Help Topics” in the main menu bar. 102019/5/9 Project Oriented ◼ This template provides a folder structure that helps you organise your model data. You may modify the template as desired, for instance by deleting folders or adding new folders. ◼ Open application “MIKE Zero” ◼ Generate a new project folder:
- 13. “File”->”New”->””->”Project” … ◼ General template Step 1: Create a new project. ◼ Give the project a name, for example “Lake”, a folder named “Lake” will be generated and a file called “Lake.mzp” will be created as well.
- 14. Lake Step 2: Create a new model setup file - Specification file (xxx.sw) ◼ Generate a new specification file to set up a model: “File”->”New”->”MIKE 21”->”Spectral Waves FM” ◼ Save as “filename.sw”, e.g. “Lake.sw” Step 3: Set up the specification file – Basic Parameters 3.1 Set up domain
- 15. 3.2 Select mesh (bathymetry) file Details on mesh generation can be found at “MIKE Zero Mesh Generator, Step-by-step training guide” uploaded at [email protected] 3.3 Define boundary names Details on mesh generation can be found at “MIKE Zero Mesh Generator, Step-by-step training guide” uploaded at [email protected] The Universal Transverse Mercator System UTM Zone conversion ◼ The Universal Transverse Mercator Coordinate (UTM) system provides
- 16. coordinates on a world wide flat grid for easy computation. The Universal Transverse Mercator Coordinate system divides the World into 60 zones, each being 6 degrees longitude wide, and extending from 80 degrees south latitude to 84 degrees north latitude. The polar regions are excluded. The first zone starts at the International Date Line (longitude 180 degrees) proceeding eastward. ◼ To find the grid zone for any longitude: ◼ Treat west longitude as negative and east as positive. ◼ Add 180 degrees; this converts the longitude to a number between zero and 360 degrees.
- 17. ◼ Divide by 6 and round up to the next higher number. ��� = ������� ����������+180 6 +1 http://www.uwgb.edu/dutchs/FieldMethods/UTMSystem.htm http://www.ngs.noaa.gov/TOOLS/utm.shtml http://www.uwgb.edu/dutchs/FieldMethods/UTMSystem.htm Bathymetry ◼ Bathymetry raw data and information data in “Bathy_MoretonSouth_data.txt” and
- 18. “Bathy_MoretonSouth_information.tx t”. ◼ Use Mikezero to create a bathymetry data file for modelling ◼ (153.283E, 27.667S) Southern Moreton Bay: 13km by 14km Displaying 2D results with Google Earth ◼ The MIKE to Google Earth is a visualisation tool to be used in conjunctionwith the Google Earth viewer to display contour maps of geo-
- 19. referenced dfs2 files, e.g. inundation flood maps or water surface maps, on top of satellite images. To use this plug-in Google Earth must be installed (http://earth.google.com/). ◼ Start -> Programs -> MIKE BY DHI 2016 -> MIKE Zero -> Tools -> MIKE to Google Earth http://earth.google.com/ 3.3 Set up Simulation Period Number of time step, n
- 20. Time interval, Dt If the wind or water level conditions are constant, the time is used to avoid the step function effect. It is better to be less than 5. CFL condition. Total simulation time = Dt x n (s) Number of time step, n Time interval, Dt Total simulation time = Dt x n (s) Courant number
- 21. Closed boundary ◼ An offshore boundary where no wave information is available - most often treated as an absorbing (land) boundary. No waves can enter the model domain from this type of boundary and waves propagating out of the domain are fully absorbed. Open Boundary ◼ If offshore wave data is available (e.g. wave measurements or data derived from a MIKE 21 SW simulation), an essential boundary can be chosen.
- 22. ◼ The boundary conditions can be described through either a parameterized formulation (Hm0, Tp, etc.) or a wave spectrum. The wave boundary conditions can be variable in time and space. Step 4: Set up the specification file – Spectral Wave Module 4.1 Set up – Basic Equations 302019/5/9 directional-frequency wave action spectrum is the dependent variable the zeroth and first moment of the wave action
- 23. spectrum as dependent variables a steady state solution is calculated at each time step wave studies involving wave growth 4.2 Set up – Spectral Discretization 312019/5/9 Two types of discretisation are available; logarithmic and equidistant distribution. It is recommended to always use the logarithmic distribution of frequencies, which is given by �� = �0� � � = 1, 2, …
- 24. where fn is the frequency, f0 minimum frequency and c the frequency factor (= 1.1 as default). The frequency range should cover wave frequencies expected to occur in the computational domain. For typical offshore applications wave periods from 4 s to 25 s (i.e. frequencies from 0.25 Hz to 0.04 Hz) are found. In enclosed waters wave periods of 2-3 s (i.e. frequencies from 0.33 Hz to 0.5 Hz) may also be of interest and should be resolved. 4.3 Set up –