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Start-up


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PROJect 'name' 'nr'

        'title1'

        'title2'

        'title3'

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With this required command the user defines a number of strings to identify the SWAN run (project name e.g., an engineering project) in the print and plot file.

'name' is the name of the project, at most 16 characters long.  
  Default: blanks.  
'nr' is the run identification (to be provided as a character string; e.g. the run  
  number) to distinguish this run among other runs for the same project; it is at  
  most 4 characters long. It is the only required information in this command.  
'title1' is a string of at most 72 characters provided by the user to appear in the  
  output of the program for the user's convenience.  
  Default: blanks.  
'title2' same as 'title1'.  
'title3' same as 'title1'.  


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SET  [level] [nor] [depmin] [maxmes] [maxerr] [grav] [rho] [cdcap]    &

                        |    NAUTical  |
     [inrhog] [hsrerr] <                > [pwtail] [froudmax]
                        | -> CARTesian |

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With this optional command the user assigns values to various general parameters.

[level] increase in water level that is constant in space and time can be given with  
  this option, [level] is the value of this increase (in m). For a variable water  
  level reference is made to the commands INPGRID and READINP.  
  Default: [level]=0.  
[nor] direction of North with respect to the x -axis (measured counterclockwise);  
  default [nor]= 90 o, i.e. x -axis of the problem coordinate system  
  points East.  
  When spherical coordinates are used (see command COORD) the value  
  of [nor] may not be modified.  
[depmin] threshold depth (in m). In the computation any positive depth smaller than  
  [depmin] is made equal to [depmin].  
  Default: [depmin] = 0.05.  
[maxmes] maximum number of error messages (not necessarily the number of errors!)  
  during the computation at which the computation is terminated. During the  
  computational process messages are written to the print file.  
  Default: [maxmes] = 200.  
[maxerr] during pre-processing SWAN checks input data. Depending on the severity  
  of the errors encountered during this pre-processing, SWAN does not start  
  computations. The user can influence the error level above which SWAN will  
  not start computations (at the level indicated the computations will continue).  
  The error level [maxerr] is coded as follows:  
  1 : warnings,  
  2 : errors (possibly automatically repaired or repairable by SWAN),  
  3 : severe errors.  
  Default: [maxerr] = 1.  
[grav] is the gravitational acceleration (in m/s2).  
  Default: [grav] = 9.81.  
[rho] is the water density $ \rho$ (in kg/m3).  
  Default: [rho] = 1025.  
[cdcap] is the maximum value for the wind drag coefficient. A value of [cdcap] = 99999  
  means no cutting off the drag coefficient. A suggestion for this parameter is  
  [cdcap] = 2.5x 10-3.  
  Default: [cdcap] = 99999.  
[inrhog] to indicate whether the user requires output based on variance or based on true  
  energy (see Section 2.5).  
  [inrhog] = 0 : output based on variance  
  [inrhog] = 1 : output based on true energy  
  Default: [inrhog] = 0.  
[hsrerr] the relative difference between the user imposed significant wave height and the  
  significant wave height computed by SWAN (anywhere along the computational  
  grid boundary) above which a warning will be given. This relative difference  
  is the difference normalized with the user provided significant wave height. This  
  warning will be given for each boundary grid point where the problem occurs  
  (with its x - and y -index number of the computational grid). The cause of the  
  difference is explained in Section 2.6.3. To supress these warnings (in particular  
  for nonstationary computations), set [hsrerr] at a very high value or use  
  command OFF BNDCHK.  
  Default: [hsrerr] = 0.10.  
  ONLY MEANT FOR STRUCTURED GRIDS.  
NAUTICAL indicates that the Nautical convention for wind and wave direction (SWAN input  
  and output) will be used instead of the default Cartesian convention.  
  For definition, see Section 2.5 or Appendix A.  
CARTESIAN indicates that the Cartesian convention for wind and wave direction (SWAN input  
  and output) will be used. For definition, see Section 2.5 or Appendix A.  
[pwtail] power of high frequency tail; defines the shape of the spectral tail above the  
  highest prognostic frequency [fhigh] (see command CGRID). The energy density  
  is assumed to be proportional to frequency to the power [pwtail].  
  Default values depend on formulations of physics:  
  command GEN1 : [pwtail] = 5  
  command GEN2 : [pwtail] = 5  
  command GEN3 KOMEN : [pwtail] = 4  
  command GEN3 JANSSEN : [pwtail] = 5  
  If the user wishes to use another value, then this SET command should be  
  located in the command file after the GEN1, GEN 2 or GEN3 command  
  (these will override the SET command with respect to [pwtail]).  
[froudmax] is the maximum Froude number ( U/$ \sqrt{{gd}}$ with U the current and d the water  
  depth). The currents taken from a circulation model may mismatch with given  
  water depth d in the sense that the Froude number becomes larger than 1.  
  For this, the current velocities will be maximized by Froude number times $ \sqrt{{gd}}$.  
  Default: [froudmax] = 0.8.  


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      |-> STATionary    |     |-> TWODimensional |
MODE <                   >   <                    >
      |   NONSTationary |     |   ONEDimensional |

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With this optional command the user indicates that the run will be either stationary or nonstationary and one-dimensional (1D-mode) or two-dimensional (2D-mode). Non-stationary means either (see command COMPUTE):

(a)
one nonstationary computations or
(b)
a sequence of stationary computations or
(c)
a mix of (a) and (b).
The default option is STATIONARY TWODIMENSIONAL.


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             | -> CARTesian                 |
COORDINATES <                  | -> CCM |    > REPeating
             |    SPHErical   <          >  |
                               |  QC    |

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Command to choose between Cartesian and spherical coordinates (see Section 2.5).


A nested SWAN run must use the same coordinate system as the coarse grid SWAN run.

CARTESIAN all locations and distances are in m. Coordinates are given with respect  
  to x - and y -axes chosen by the user in the various commands.  
SPHERICAL all coordinates of locations and geographical grid sizes are given in degrees;  
  x is longitude with x = 0 being the Greenwich meridian and x > 0 is East of  
  this meridian; y is latitude with y > 0 being the Northern hemisphere. Input  
  and output grids have to be oriented with their x -axis to the East; mesh sizes  
  are in degrees. All other distances are in meters.  
CCM defines the projection method in case of spherical coordinates. CCM means  
  central conformal Mercator. The horizontal and vertical scales are uniform  
  in terms of cm/degree over the area shown. In the centre of the scale is  
  identical to that of the conventional Mercator projection (but only at that  
  centre). The area in the projection centre is therefore exactly conformal.  
QC the projection method is quasi-cartesian, i.e. the horizontal and vertical scales  
  are equal to one another in terms of cm/degree.  
REPEATING this option is only for academic cases. It means that wave energy leaving at one  
  end of the domain (in computational x -direction) enter at the other side; it is  
  as if the wave field repeats itself in x -direction with the length of the domain  
  in x -direction.  
  This option cannot be used in combination with computation of set-up (see  
  command SETUP). This option is available only with regular grids.  

Note that spherical coordinates can also be used for relatively small areas, say 10 or 20 km horizontal dimension. This may be useful if one obtains the boundary conditions by nesting in an oceanic model which is naturally formulated in spherical coordinates.


Note that in case of spherical coordinates regular grids must always be oriented E-W, N-S, i.e. [alpc]=0, [alpinp]=0, [alpfr]=0 (see commands CGRID, INPUT GRID and FRAME, respectively).


next up previous index
Next: Model description Up: Description of commands Previous: Command syntax and input   Index
The SWAN team 2017-10-26