source: branches/numpy/anuga/config.py @ 6553

Last change on this file since 6553 was 6553, checked in by rwilson, 15 years ago

Merged trunk into numpy, all tests and validations work.

File size: 8.9 KB
Line 
1"""Module where global ANUGA model parameters and default values are set
2"""
3
4import os
5import sys
6import numpy as num
7
8
9################################################################################
10# numerical constants
11################################################################################
12
13epsilon = 1.0e-12                    # Smallest number - used for safe division
14max_float = 1.0e36                   # Largest number - used to initialise
15                                     # (max, min) ranges
16default_smoothing_parameter = 0.001  # Default alpha for penalised
17                                     # least squares fitting
18single_precision = 1.0e-6            # Smallest single precision number
19velocity_protection = 1.0e-6                                     
20
21################################################################################
22# Standard filenames, directories and system parameters used by ANUGA
23################################################################################
24
25pmesh_filename = '.\\pmesh'
26version_filename = 'stored_version_info.py'
27default_datadir = '.'
28time_format = '%d/%m/%y %H:%M:%S'
29umask = 002  # Controls file and directory permission created by anuga
30default_boundary_tag = 'exterior' 
31
32# Major revision number for use with create_distribution
33# and update_anuga_user_guide
34major_revision = '1.0beta'
35
36################################################################################
37# Physical constants
38################################################################################
39
40manning = 0.03  # Manning's friction coefficient
41#g = 9.80665    # Gravity - FIXME reinstate this and fix unit tests.
42g = 9.8
43#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
44#The 'official' average is 9.80665
45
46eta_w = 3.0e-3 # Wind stress coefficient
47rho_a = 1.2e-3 # Atmospheric density
48rho_w = 1023   # Fluid density [kg/m^3] (rho_w = 1023 for salt water)
49
50################################################################################
51# Limiters - used with linear reconstruction of vertex
52# values from centroid values
53################################################################################
54
55# Betas [0;1] control the allowed steepness of gradient for second order
56# extrapolations. Values of 1 allow the steepes gradients while
57# lower values are more conservative. Values of 0 correspond to
58# 1'st order extrapolations.
59#
60
61# There are separate betas for the w, uh, and vh limiters
62# I think these are better SR but they conflict with the unit tests!
63beta_w      = 1.0
64beta_w_dry  = 0.2
65beta_uh     = 1.0
66beta_uh_dry = 0.2
67beta_vh     = 1.0
68beta_vh_dry = 0.2
69
70# Alpha_balance controls how limiters are balanced between deep and shallow.
71# A large value will favour the deep water limiters, allowing the a closer hug
72# to the coastline.  This will minimise 'creep' but at the same time cause
73# smaller time steps
74# Range:
75alpha_balance = 2.0 
76
77# Flag use of new limiters.
78# tight_slope_limiters = 0 means use old limiters (e.g. for some tests)
79# tight_slope_limiters = 1 means use new limiters that hug the bathymetry closer
80tight_slope_limiters = True
81
82# Use centroid velocities to reconstruct momentum at vertices in
83# very shallow water
84# This option has a first order flavour to it, but we still have second order
85# reconstruction of stage and this option only applies in
86# balance_deep_and_shallow when
87# alpha < 1 so in deeper water the full second order scheme is used.
88#
89# This option is good with tight_slope_limiters, especially for large domains.
90use_centroid_velocities = True
91       
92# FIXME (Ole) Maybe get rid of order altogether and use beta_w
93default_order = 2
94
95################################################################################
96# Timestepping
97################################################################################
98
99CFL = 1.0  # CFL condition assigned to domain.CFL - controls timestep size
100     
101# Choose type of timestepping,
102#timestepping_method = 'rk2'   # 2nd Order TVD scheme
103timestepping_method = 'euler' # 1st order euler
104
105# rk2 is a little more stable than euler, so rk2 timestepping
106# can deal with a larger beta when slope limiting the reconstructed
107# solution. The large beta is needed if solving problems sensitive
108# to numerical diffusion, like a small forced wave in an ocean
109beta_euler = 1.0
110beta_rk2   = 1.6
111
112# Option to search for signatures where isolated triangles are
113# responsible for a small global timestep.
114# Treating these by limiting their momenta may help speed up the
115# overall computation.
116# This facility is experimental.
117# protect_against_isolated_degenerate_timesteps = False
118protect_against_isolated_degenerate_timesteps = False
119
120min_timestep = 1.0e-6 # Minimal timestep accepted in ANUGA
121max_timestep = 1.0e+3
122max_smallsteps = 50   # Max number of degenerate steps allowed b4
123                      # trying first order
124
125# Perhaps minimal timestep could be based on the geometry as follows:
126# Define maximal possible speed in open water v_max, e.g. 500m/s (soundspeed?)
127# Then work out minimal internal distance in mesh r_min and set
128# min_timestep = r_min/v_max
129#
130# Max speeds are calculated in the flux function as
131#
132# lambda = v +/- sqrt(gh)
133#
134# so with 500 m/s, h ~ 500^2/g = 2500 m well out of the domain of the
135# shallow water wave equation
136#
137# The actual soundspeed can be as high as 1530m/s
138# (see http://staff.washington.edu/aganse/public.projects/clustering/clustering.html),
139# but that would only happen with h>225000m in this equation. Why ?
140# The maximal speed we specify is really related to the max speed
141# of surface pertubation
142#
143# v_max = 100 #For use in domain_ext.c
144# sound_speed = 500
145
146################################################################################
147# Ranges specific to the shallow water wave equation
148# These control maximal and minimal values of quantities
149################################################################################
150
151# Water depth below which it is considered to be 0 in the model
152minimum_allowed_height = 1.0e-3 
153
154# Water depth below which it is *stored* as 0
155minimum_storable_height = 1.0e-5
156
157# FIXME (Ole): Redefine this parameter to control maximal speeds in general
158# and associate it with protect_against_isolated_degenerate_timesteps = True
159maximum_allowed_speed = 0.0 # Maximal particle speed of water
160#maximum_allowed_speed = 1.0 # Maximal particle speed of water
161                             # Too large (100) creates 'flopping' water
162                             # Too small (0) creates 'creep'
163
164maximum_froude_number = 100.0 # To be used in limiters.
165
166################################################################################
167# Performance parameters used to invoke various optimisations
168################################################################################
169
170use_extensions = True # Use C-extensions
171use_psyco = True      # Use psyco optimisations
172
173optimise_dry_cells = True # Exclude dry and still cells from flux computation
174optimised_gradient_limiter = True # Use hardwired gradient limiter
175use_edge_limiter = False  # The edge limiter is better, but most runs have been
176                          # using vertex limiting. Validations passed with this
177                          # one True 9th May 2008, but many unit tests need
178                          # backward compatibility flag set FIXME(Ole).
179
180points_file_block_line_size = 500 # Number of lines read in from a points file
181                                  # when blocking
182
183################################################################################
184# NetCDF-specific type constants.  Used when defining NetCDF file variables.
185################################################################################
186
187netcdf_char = 'c'
188netcdf_byte = 'b'
189netcdf_int = 'i'
190netcdf_float = 'd'
191netcdf_float64 = 'd'
192netcdf_float32 = 'f'
193
194################################################################################
195# Dynamically-defined constants.
196################################################################################
197
198# Determine if we can read/write large NetCDF files
199netcdf_mode_w = 'w'
200netcdf_mode_a = 'a'
201netcdf_mode_r = 'r'
202
203# Code to set the write mode depending on
204# whether Scientific.IO supports large NetCDF files
205s = """
206import os
207from Scientific.IO.NetCDF import NetCDFFile
208fid = NetCDFFile('tmpfilenamexx', 'wl')
209fid.close()
210os.remove('tmpfilenamexx')
211"""
212
213# Need to run in a separate process due an
214# error with older versions of Scientific.IO
215if sys.platform == 'win32':
216    null = 'NUL'
217else:
218    null = '/dev/null'
219cmd = 'python -c "%s" 2> %s' % (s, null)
220err = os.system(cmd)
221
222if err != 0:
223    # The Python script s failed e.g. with a segfault
224    # which means that large file support is
225    # definitely not supported
226    pass
227else:   
228    # Try the import within this process
229    try:
230        exec(s)
231    except IOError:
232        # NetCDFFile does not segfault but it does not
233        # support large file support   
234        pass
235    else:
236        # Set the default mode to large file support
237        netcdf_mode_w = 'wl'
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