You are viewing an old version of this page. View the current version.

Compare with Current View Page History

« Previous Version 11 Next »

Introduction

This tool allows the user setting-up or refining in few clicks an existing model. In particular, the following operations can be performed within Delft Dashboard:

  • Create or refine a computational grid (“*. grd” file)
  • Extract and interpolate bathymetry data from open source on-line databases on the computational grid (“*.dep” file).
  • Extract and interpolate tidal boundary conditions from open source on-line databases on the computational grid, creating boundary conditions for the model (“*.bnd” file).

 

Delft Dashboard contains a number of Tabs, which can be used to specify additional information to the model. The model can then be used directly to carry out hydrodynamics, waves, morphodynamics or water quality computations.

Make rectangular grid

After the grid outline is defined within the interface of Delft Dashboard the user can click on ‘Create grid’. The following routines (ddb_ModelMakerToolbox_makeRectangularGrid) will then be called:

  1. Determine the origin (xori, yori), spatial resolution (dx, dy), orientation (rot) and maximum bed level required (zmax) from the specified values in Dashboard.
  2. Create a full grid between these points (+ some buffer of 5%) based on the bathymetry active in Dashboard (default this is GEBCO ’08).  This grid will already be defined in the active coordinate system the user specified.
  3. Grid a rectangular grid within the boundaries specified in Dashboard. The grid cells which are above a certain bed level (zmax) are deleted. A linear interpolation is carried between the full grid and the rectangular grid within the boundaries

 

Figure: The rectangular grid created for New Zealand. At areas above Zmax (m) no grid cells are defined as can be seen clearly at of this example.

Make bathymetry

The (rectangular) grid defined with ‘make grid’ also needs a bathymetry. The user can click on ‘Create bathymetry’. The following routines (ddb_ModelMakerToolbox_bathymetry) will then be called:

  1. Determine which datasets are used and within which limit (zmin and zmax). This feature is especially handy when a different data set is used for the sea part and the land part. An offset can be used in order to shift the bathmetry. Diffusion is used for defining depth values for missing data (NaNs).
    1. If in quick mode ‘make bathymetry’ is used the active bathymetry in Dashboard (default GEBCO ’08) is applied
    2. Other bathymetry sets can be important via the Toolbox ‘Bathmetry’. More about this toolbox can be found in @.
  2. The function will now loop over the different dataset
    1. The bathymetry is first loaded.
      1. This can be downloaded from the OpenDAP server
      2. Or from your local directory file if the data needed is used in a previous set-up.
    2. Bathymetries are applied in the order defined.
    3. Interpolation from the original grid to the model grid is carried out with a linear interpolation. Only values (that are not NaN) are taken into account
  3. If an internal diffusion is applied the remaining non existing bed levels are filled in based on the mean bed level and after that a smoothing function is applied
  4. If a model offset is applied the whole bathymetry is shifted. An offset of 1 meter means the bed level will be 1 meter lower than originally.
  5. The bathymetry created is directly visible in Delft Dashboard.

Figure: The bathymetry created for New Zealand. The colors in Delft Dashboard are updated based on the value defined to the specific grid cell. 

Boundary conditions

The model now has a grid and bathymetry, but the boundary conditions forcing the model need to be defined next. This option differs per model.

 

For Delft3D-flow the following routines can be called

  1. Make open boundaries, this will result in the following routines (ddb_generateBoundaryLocationsDelft3DFLOW)
    1. Loading the defined the entire boundary of the model grid
    2. Determining which cross-sections are ‘open’. This is related with the bed level in the grid cell and the maximum bed level defined (zmax). The number of ‘open’ boundaries is determined with the value in the ‘cells per section’
    3. All the defined boundaries will get initial values in order to be initialized. This will however only mean an M2 and S2 harmonic with the amplitude of 1. The names given will be related with the location and the number of open cross-section (for example: ‘West 2’)
  2. Make boundary conditions, this will result in the following routines (ddb_generateBoundaryConditionsDelft3DFLOW)
    1. Loading the locations (x and y) of the different open boundaries and the start and stop time.
    2. Per location the amplitudes and phases will be determined. This will be based on a larger netCDF file were in a grid format phases and amplitude are stored for all latitude and longitude. In total 14 constituents are determined.
      1. Standard the boundary type is a water level. However, it is also possible to describe a current, Neumann, Riemann, etc.
      2. For the areas were no values are stored diffusion is applied
      3. A linear interpolation is used for the areas were an open boundary is described

Other

The Model Maker for Delft3D-FLOW has two additional possibilities:

  • Initial conditions: determine if the simulation should start with an uniform water level or velocity
  • Roughness: create a roughness file with a seperate Manning value for land and sea. 

 

 

  • No labels

Disclaimer