source: trunk/anuga_core/source/anuga/config.py @ 7841

Last change on this file since 7841 was 7841, checked in by hudson, 12 years ago

Refactorings to allow tests to pass.

File size: 9.3 KB
Line 
1"""Module where global ANUGA model parameters and default values are set
2"""
3
4import os
5import sys
6
7
8################################################################################
9# Numerical constants
10################################################################################
11
12epsilon = 1.0e-12                    # Smallest number - used for safe division
13max_float = 1.0e36                   # Largest number - used to initialise
14                                     # (max, min) ranges
15default_smoothing_parameter = 0.001  # Default alpha for penalised
16                                     # least squares fitting
17single_precision = 1.0e-6            # Smallest single precision number
18velocity_protection = 1.0e-6         # Used to compute velocity from momentum
19                                     # See section 7.4 on Flux limiting
20                                     # in the user manual
21                           
22
23################################################################################
24# Standard filenames, directories and system parameters used by ANUGA
25################################################################################
26
27pmesh_filename = '.\\pmesh'
28version_filename = 'stored_version_info.py'
29default_datadir = '.'
30time_format = '%d/%m/%y %H:%M:%S'    # Used with timefile2netcdf
31umask = 002  # Controls file and directory permission created by anuga (UNIX)
32default_boundary_tag = 'exterior' 
33
34# Major revision number for use with create_distribution
35# and update_anuga_user_guide
36major_revision = '1.2'
37
38################################################################################
39# Physical constants
40################################################################################
41
42manning = 0.03  # Manning's friction coefficient
43#g = 9.80665    # Gravity - FIXME reinstate this and fix unit tests.
44g = 9.8
45#g(phi) = 9780313 * (1 + 0.0053024 sin(phi)**2 - 0.000 0059 sin(2*phi)**2) micro m/s**2, where phi is the latitude
46#The 'official' average is 9.80665
47
48eta_w = 3.0e-3 # Wind stress coefficient
49rho_a = 1.2e-3 # Atmospheric density
50rho_w = 1023   # Fluid density [kg/m^3] (rho_w = 1023 for salt water)
51
52################################################################################
53# Limiters - used with linear reconstruction of vertex
54# values from centroid values
55################################################################################
56
57# Betas [0;1] control the allowed steepness of gradient for second order
58# extrapolations. Values of 1 allow the steepes gradients while
59# lower values are more conservative. Values of 0 correspond to
60# 1'st order extrapolations.
61#
62
63# There are separate betas for the w, uh, and vh limiters
64# I think these are better SR but they conflict with the unit tests!
65beta_w      = 1.0
66beta_w_dry  = 0.2
67beta_uh     = 1.0
68beta_uh_dry = 0.2
69beta_vh     = 1.0
70beta_vh_dry = 0.2
71
72# Alpha_balance controls how limiters are balanced between deep and shallow.
73# A large value will favour the deep water limiters, allowing the a closer hug
74# to the coastline.  This will minimise 'creep' but at the same time cause
75# smaller time steps
76# Range:
77alpha_balance = 2.0 
78
79# Flag use of new limiters.
80# tight_slope_limiters = 0 means use old limiters (e.g. for some tests)
81# tight_slope_limiters = 1 means use new limiters that hug the bathymetry closer
82tight_slope_limiters = True
83
84# Use centroid velocities to reconstruct momentum at vertices in
85# very shallow water
86# This option has a first order flavour to it, but we still have second order
87# reconstruction of stage and this option only applies in
88# balance_deep_and_shallow when
89# alpha < 1 so in deeper water the full second order scheme is used.
90#
91# This option is good with tight_slope_limiters, especially for large domains.
92use_centroid_velocities = True
93       
94# FIXME (Ole) Maybe get rid of order altogether and use beta_w
95default_order = 2
96
97################################################################################
98# Timestepping
99################################################################################
100
101CFL = 1.0  # CFL condition assigned to domain.CFL - controls timestep size
102     
103# Choose type of timestepping,
104#timestepping_method = 'rk2'   # 2nd Order TVD scheme
105timestepping_method = 'euler' # 1st order euler
106
107# rk2 is a little more stable than euler, so rk2 timestepping
108# can deal with a larger beta when slope limiting the reconstructed
109# solution. The large beta is needed if solving problems sensitive
110# to numerical diffusion, like a small forced wave in an ocean
111beta_euler = 1.0
112beta_rk2   = 1.6
113
114# Option to search for signatures where isolated triangles are
115# responsible for a small global timestep.
116# Treating these by limiting their momenta may help speed up the
117# overall computation.
118# This facility is experimental.
119# protect_against_isolated_degenerate_timesteps = False
120protect_against_isolated_degenerate_timesteps = False
121
122min_timestep = 1.0e-6 # Minimal timestep accepted in ANUGA
123max_timestep = 1.0e+3
124max_smallsteps = 50   # Max number of degenerate steps allowed b4
125                      # trying first order
126
127# Perhaps minimal timestep could be based on the geometry as follows:
128# Define maximal possible speed in open water v_max, e.g. 500m/s (soundspeed?)
129# Then work out minimal internal distance in mesh r_min and set
130# min_timestep = r_min/v_max
131#
132# Max speeds are calculated in the flux function as
133#
134# lambda = v +/- sqrt(gh)
135#
136# so with 500 m/s, h ~ 500^2/g = 2500 m well out of the domain of the
137# shallow water wave equation
138#
139# The actual soundspeed can be as high as 1530m/s
140# (see http://staff.washington.edu/aganse/public.projects/clustering/clustering.html),
141# but that would only happen with h>225000m in this equation. Why ?
142# The maximal speed we specify is really related to the max speed
143# of surface pertubation
144#
145# v_max = 100 #For use in domain_ext.c
146# sound_speed = 500
147
148################################################################################
149# Ranges specific to the shallow water wave equation
150# These control maximal and minimal values of quantities
151################################################################################
152
153# Water depth below which it is considered to be 0 in the model
154minimum_allowed_height = 1.0e-3 
155
156# Water depth below which it is *stored* as 0
157minimum_storable_height = 1.0e-5
158
159# FIXME (Ole): Redefine this parameter to control maximal speeds in general
160# and associate it with protect_against_isolated_degenerate_timesteps = True
161maximum_allowed_speed = 0.0 # Maximal particle speed of water
162#maximum_allowed_speed = 1.0 # Maximal particle speed of water
163                             # Too large (100) creates 'flopping' water
164                             # Too small (0) creates 'creep'
165
166maximum_froude_number = 100.0 # To be used in limiters.
167
168################################################################################
169# Performance parameters used to invoke various optimisations
170################################################################################
171
172use_extensions = True # Use C-extensions
173use_psyco = True      # Use psyco optimisations
174
175optimise_dry_cells = True # Exclude dry and still cells from flux computation
176optimised_gradient_limiter = True # Use hardwired gradient limiter
177use_edge_limiter = False  # The edge limiter is better, but most runs have been
178                          # using vertex limiting. Validations passed with this
179                          # one True 9th May 2008, but many unit tests need
180                          # backward compatibility flag set FIXME(Ole).
181
182points_file_block_line_size = 500 # Number of lines read in from a points file
183                                  # when blocking
184
185################################################################################
186# NetCDF-specific type constants.  Used when defining NetCDF file variables.
187################################################################################
188
189netcdf_char = 'c'
190netcdf_byte = 'b'
191netcdf_int = 'i'
192netcdf_float = 'd'
193netcdf_float64 = 'd'
194netcdf_float32 = 'f'
195
196################################################################################
197# Dynamically-defined constants.
198################################################################################
199
200# Determine if we can read/write large NetCDF files
201netcdf_mode_w = 'w'
202netcdf_mode_a = 'a'
203netcdf_mode_r = 'r'
204
205# Code to set the write mode depending on
206# whether Scientific.IO supports large NetCDF files
207s = """
208import os, tempfile
209from Scientific.IO.NetCDF import NetCDFFile
210
211filename = tempfile.mktemp('.nc')
212
213fid = NetCDFFile(filename, 'wl')
214fid.close()
215os.remove(filename)
216"""
217
218# Need to run in a separate process due an
219# error with older versions of Scientific.IO
220if sys.platform == 'win32':
221    null = 'NUL'
222else:
223    null = '/dev/null'
224cmd = 'python -c "%s" 2> %s' % (s, null)
225err = os.system(cmd)
226
227if err != 0:
228    # The Python script s failed e.g. with a segfault
229    # which means that large file support is
230    # definitely not supported
231    pass
232else:   
233    # Try the import within this process
234    try:
235        exec(s)
236    except IOError:
237        # NetCDFFile does not segfault but it does not
238        # support large file support   
239        pass
240    else:
241        # Set the default mode to large file support
242        #netcdf_mode_w = 'w4' # Future use of HDF5       
243        netcdf_mode_w = 'wl' # Large NetCDF (new default 30/6/2009)
244        #netcdf_mode_w = 'w'   # Old style NetCDF used by OSG viewer
245
246
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