Specifying GeoClaw parameters in setrun.py

Since GeoClaw is a modified version of AMRClaw, all of the parameters that are required for AMRClaw are also needed by GeoClaw. See Specifying AMRClaw parameters in setrun.py for a discussion of these, and Specifying run-time parameters in setrun.py for a description of setrun.py input scripts more generally.

In addition, a number of other parameters should be set in the setrun.py file in any GeoClaw application. See also the Cautionary Hints on using GeoClaw for more about parameter choices.

It is best to look at a specific example while reading this section, for example Sample GeoClaw setrun.py module.

The function setrun in this module is essentially the same as for AMRClaw, except that it expects to be called with claw_pkg = ‘geoclaw’. This call should be performed properly by the Makefile if you have CLAW_PKG = geoclaw set properly there.

The new section setgeo function in this module contains the new GeoClaw parameters.

A brief summary of these:

Refinement factors in time

New in 4.6.0: It is now possible to have GeoClaw automatically choose refinement factors in time on each level based on an estimate of the maximum wave speed on all grids at this level. For most hyperbolic problems the CFL condition suggests that one should refine in time by the same factor as in space. However, for GeoClaw applications where fine grids appear only in shallow coastal regions this may not be the case. Automatic choice of refinement factors is used if

variable_dt_refinement_ratios : bool

is set to True. The default is False, in which case refinement factors in time are specified by the user as usual.

General geo parameters

igravity : integer

igravity = 1 should be set in general.

gravity : float

gravitational constant in m/s**2, e.g. gravity = 9.81.

icoordsys : integer

icoordsys = 1 for Cartesian x-y in meters,

icoordsys = 2 for latitude-longitude on the sphere.

Rearth : float

radius of the earth in meters, e.g. Rearth = 6367.5e3.

icoriolis : integer

icoriolis = 1 to include Coriolis terms in momentum equations

icoriolis = 0 to omit Coriolis terms (usually fine for tsunami modeling)

Tsunami parameters

These parameters are used for tsunami modeling (can also be used for other problems — need to clarify this!).

sealevel : float

sea level (often sealevel = 0.) This is relative to the 0 vertical datum of the topography files used.

wavetolerance : float

Cells are flagged for refinement if the difference between the surface elevation and sea level is larger than this tolerance. Note that whether refinement is actually done depends also on how various AMR regions have been set (see Section Specifying AMR regions) and also on several other attributes described below that contain information on minimum and maximum refinement allowed in various regions.

maxleveldeep : float

For simulations over the ocean, it is often useful to specify a maximum refinement level allowed in deep parts of the ocean. This is useful if a high level of refinement is specified on some rectangular region but only the parts of this region near the shore actually need to be refined.

depthdeep : float

The deepness that triggers the refinement limitation imposed by maxleveldeep above.

ifriction : integer

This is not actually used in the code and will be deprecated. If coeffmanning > 0 then friction terms will be applied, regardless of the value of ifriction.

coeffmanning : float

For friction source terms, the Manning coefficient. See Manning friction term.

frictiondepth : float

Friction source terms are only applied in water shallower than this, since they have negligible effect in deeper water.

Topography data file parameters

See Topography data for more information about specifying topography (and bathymetry) data files in GeoClaw.

topofiles : list of lists

topofiles should be a list of the form [file1info, file2info, etc.] where each element is itself a list of the form

[topotype, minlevel, maxlevel, t1, t2, fname]

with values

topotype : integer

1,2 or 3 depending on the format of the file (see Topography data).

minlevel : integer

the minimum refinement level that should be enforced in the region covered by this grid (for times between t1 and t2).

maxlevel : integer

the maximum refinement level that should be allowed in the region covered by this grid (for times between t1 and t2).

t1, t2 : floats

the time interval over which refinement should be controlled.

fname : string

the name of the topo file.

For more about controlling AMR in various regions, see Specifying AMR regions.

dtopofiles : list of lists

Information about topography displacement files, giving perturbations to topography generated by an earthquake, for example.

dtopofiles should be a list of the form [] or [file1info] where each element (currently at most 1 is allowed!) is itself a list of the form

[dtopotype, minlevel, maxlevel, fname]

with values

dtopotype : integer

1 or 3 depending on the format of the file (see Topography displacement files).

minlevel : integer

the minimum refinement level that should be enforced in the region covered by this grid.

maxlevel : integer

the maximum refinement level that should be allowed in the region covered by this grid.

fname : string

the name of the dtopo file. See Topography displacement files for information about the format of data in this file.

qinit data file parameters

A modification to the initial data specified by default can be made as described at qinit data file.

iqinit : integer

Specifies what type of perturbation is stored in the qinitfile, see qinit data file for more information. Valid values for iqinit are

• 0 = No perturbation specified
• 1 = Perturbation to depth h
• 2 = Perturbation to x-momentum hu
• 3 = Perturbation to y-momentum hv
• 4 = Perturbation to surface level

qinitfiles : list of lists

qinitfiles should be a list of the form [] or [file1info] where each element (currently at most 1 is allowed!) is itself a list of the form

[minlevel, maxlevel, fname]

with values

minlevel : integer

the minimum refinement level that should be enforced in the region covered by this grid.

maxlevel : integer

the maximum refinement level that should be allowed in the region covered by this grid.

fname : string

the name of the qinitdata file. See Topography data for information about the format of data in this file.

See qinit data file for more details about the format.

AMR refinement region parameters

regions : list of lists

Note: this should become a more general AMR parameter.

regions should be a list of the form [region1info, region2info, etc.] where each element is itself a list of the form

[minlevel, maxlevel, t1, t2, x1, x2, y1, y2]

with values

minlevel : integer

the minimum refinement level that should be enforced in the region covered by this grid (for times between t1 and t2).

maxlevel : integer

the maximum refinement level that should be allowed in the region covered by this grid (for times between t1 and t2).

t1, t2 : floats

the time interval over which refinement should be controlled.

x1, x2, y1, y2 : floats

the spacial extent of this region.

For more about controlling AMR in various regions, see Specifying AMR regions.

Gauge parameters

gauges : list of lists

Note: this should become a more general AMR parameter.

gauges should be a list of the form [gauge1info, gauge2info, etc.] where each element is itself a list of the form

[gaugeno, x, y, t1, t2]

with values

gaugeno : integer

the number of this gauge

x, y : floats

the location of this gauge

t1, t2 : floats

the time interval over which gauge data should be output.

For more about gauges, see Gauges.

Fixed grid output parameters

fixedgrids : list of lists

Note: this might become a more general AMR parameter.

This can be used to specify a set of grids where output should be produced at the specified resolution regardless of how the AMR grids look at each time. Interpolation from the best available grid near each point is used. This is useful for comparing AMR output to results obtained with other codes that use a fixed grid.

fixedgrids should be a list of the form [grid1info, grid2info, etc.] where each element is itself a list of the form

[t1, t2, x1, x2, y1, y2, xpoints, ypoints]

with values

t1, t2 : floats

the time interval over which output should be written for this grid.

x1, x2, y1, y2 : floats

the spacial extent of this grid.

xpoints, ypoints : floats

the number of grid points in the x and y directions (the grid will include x1, x2 and xpoints-2 points in between, for example).