
Basic Parameters
115
depth in combination with the minimum wave period, see Selecting the grid
spacing below.
Selecting the grid spacing
It is important that the grid size is selected to provide adequate resolution of
the main characteristics of the waves under consideration. For short wave
applications the main requirement is usually that the grid size is sufficiently
small to adequately resolve the individual waves to be used in each model
simulation.
For most practical 2 DH applications 7-10 grid points per wave length will be
sufficient. Hence, it is necessary to estimate the smallest wave length in the
model area. This will be found for the shortest wave period in the most shal-
low part of the model bathymetry. A typical spatial resolution is 2-5 m.
When wave breaking and wave run-up is included, the minimum water depth
is theoretically zero and a very small spatial resolution is required to resolve
the wave field.
In practical applications it has been found that the most
energetic waves should be resolved by at least 20-40 grid points in the
surf and swash zone
. In practical 2DH applications with wave breaking and
moving shoreline a spatial resolution of 1-2 m is often used. For cross-shore
simulations using the 1DH module an unstructured mesh is often used where
the relative resolution is fixed, say, 40 nodes per wave length for the entire
profile.
Further it is required that the grid spacing in combination with the time step is
selected to fulfil the CFL (Courant number) criterion.
Important:
The Courant number should always be equal to, or less than, 1 in
2DH applications and less than about 0.5 in 1DH applications.
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Страница 1: ...MIKE 2017 MIKE 21 BW Boussinesq Waves Module User Guide...
Страница 2: ...2...
Страница 4: ...4 MIKE 21 BW DHI...
Страница 13: ...General Description 13 Figure 2 4 Simulation of wave penetration into Frederikshavn harbour Denmark...
Страница 16: ...Introduction 16 MIKE 21 BW DHI...
Страница 75: ...2DH Boussinesq Wave Module Examples 75 Figure 4 45 Visualisation 2D of instantaneous surface elevation...
Страница 185: ...Entries Arranged Alphabetically 185 Figure 5 58 Application of different time extrapolation factors...
Страница 190: ...Reference Manual 190 MIKE 21 BW DHI...
Страница 192: ...Scientific Documentation 192 MIKE 21 BW DHI...
Страница 193: ...193 INDEX...