Boundary conditions

When the model in Dashboard has a grid and bathymetry, the boundary conditions can be defined. Currently, boundary conditions in the Model Maker are only implemented for Delft3D-FLOW.

 

The following routines can be called:

  1. Make open boundaries, this will result in the following routines
    1. Loading the defined bathymetry and grid.
    2. Determining which cross-sections are ‘open’. This is related to the bed level in the grid cell and the maximum bed level defined (Z max). The number of ‘open’ boundaries is determined by the value in the ‘cells per section’. There are two options how to determine this.
      1. Equidistant over the entire boundary section. The result is that all boundary sections have an equivalent length.
      2. Related to the bed level. The result is that in the area with more variation in the bed (near the shore) more boundary sections are created. This is especially beneficial if you are using Riemann boundaries which are depth-depended.
    3. All the defined boundaries will get initial values in order to be initialized. This translates to M2 and S2 harmonics with the amplitude of 1. The names given will be related to the location and the number of the open cross-section (for example: ‘West 2’)
  2. Make boundary conditions, this will result in the following routines 
    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 in which a grid format, phases and amplitude are stored for the entire earth. In total 14 constituents are determined.
      1. The standard boundary type is a water level. It is also possible to describe a current, Neumann or Riemann boundary.
      2. For the areas where no values are stored, diffusion is applied
      3. A linear interpolation is used for the areas next to an open boundary

Other features for Delft3D-FLOW

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

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