"""Module where global ANUGA model parameters and default values are set """ import os import sys ################################################################################ # Numerical constants ################################################################################ epsilon = 1.0e-12 # Smallest number - used for safe division max_float = 1.0e36 # Largest number - used to initialise # (max, min) ranges default_smoothing_parameter = 0.001 # Default alpha for penalised # least squares fitting single_precision = 1.0e-6 # Smallest single precision number velocity_protection = 1.0e-6 # Used to compute velocity from momentum # See section 7.4 on Flux limiting # in the user manual ################################################################################ # Standard filenames, directories and system parameters used by ANUGA ################################################################################ pmesh_filename = '.\\pmesh' version_filename = 'stored_version_info.py' default_datadir = '.' time_format = '%d/%m/%y %H:%M:%S' # Used with timefile2netcdf umask = 002 # Controls file and directory permission created by anuga (UNIX) default_boundary_tag = 'exterior' # Major revision number for use with create_distribution # and update_anuga_user_guide major_revision = '1.1beta' ################################################################################ # Physical constants ################################################################################ manning = 0.03 # Manning's friction coefficient #g = 9.80665 # Gravity - FIXME reinstate this and fix unit tests. g = 9.8 #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 #The 'official' average is 9.80665 eta_w = 3.0e-3 # Wind stress coefficient rho_a = 1.2e-3 # Atmospheric density rho_w = 1023 # Fluid density [kg/m^3] (rho_w = 1023 for salt water) ################################################################################ # Limiters - used with linear reconstruction of vertex # values from centroid values ################################################################################ # Betas [0;1] control the allowed steepness of gradient for second order # extrapolations. Values of 1 allow the steepes gradients while # lower values are more conservative. Values of 0 correspond to # 1'st order extrapolations. # # There are separate betas for the w, uh, and vh limiters # I think these are better SR but they conflict with the unit tests! beta_w = 1.0 beta_w_dry = 0.2 beta_uh = 1.0 beta_uh_dry = 0.2 beta_vh = 1.0 beta_vh_dry = 0.2 # Alpha_balance controls how limiters are balanced between deep and shallow. # A large value will favour the deep water limiters, allowing the a closer hug # to the coastline. This will minimise 'creep' but at the same time cause # smaller time steps # Range: alpha_balance = 2.0 # Flag use of new limiters. # tight_slope_limiters = 0 means use old limiters (e.g. for some tests) # tight_slope_limiters = 1 means use new limiters that hug the bathymetry closer tight_slope_limiters = True # Use centroid velocities to reconstruct momentum at vertices in # very shallow water # This option has a first order flavour to it, but we still have second order # reconstruction of stage and this option only applies in # balance_deep_and_shallow when # alpha < 1 so in deeper water the full second order scheme is used. # # This option is good with tight_slope_limiters, especially for large domains. use_centroid_velocities = True # FIXME (Ole) Maybe get rid of order altogether and use beta_w default_order = 2 ################################################################################ # Timestepping ################################################################################ CFL = 1.0 # CFL condition assigned to domain.CFL - controls timestep size # Choose type of timestepping, #timestepping_method = 'rk2' # 2nd Order TVD scheme timestepping_method = 'euler' # 1st order euler # rk2 is a little more stable than euler, so rk2 timestepping # can deal with a larger beta when slope limiting the reconstructed # solution. The large beta is needed if solving problems sensitive # to numerical diffusion, like a small forced wave in an ocean beta_euler = 1.0 beta_rk2 = 1.6 # Option to search for signatures where isolated triangles are # responsible for a small global timestep. # Treating these by limiting their momenta may help speed up the # overall computation. # This facility is experimental. # protect_against_isolated_degenerate_timesteps = False protect_against_isolated_degenerate_timesteps = False min_timestep = 1.0e-6 # Minimal timestep accepted in ANUGA max_timestep = 1.0e+3 max_smallsteps = 50 # Max number of degenerate steps allowed b4 # trying first order # Perhaps minimal timestep could be based on the geometry as follows: # Define maximal possible speed in open water v_max, e.g. 500m/s (soundspeed?) # Then work out minimal internal distance in mesh r_min and set # min_timestep = r_min/v_max # # Max speeds are calculated in the flux function as # # lambda = v +/- sqrt(gh) # # so with 500 m/s, h ~ 500^2/g = 2500 m well out of the domain of the # shallow water wave equation # # The actual soundspeed can be as high as 1530m/s # (see http://staff.washington.edu/aganse/public.projects/clustering/clustering.html), # but that would only happen with h>225000m in this equation. Why ? # The maximal speed we specify is really related to the max speed # of surface pertubation # # v_max = 100 #For use in domain_ext.c # sound_speed = 500 ################################################################################ # Ranges specific to the shallow water wave equation # These control maximal and minimal values of quantities ################################################################################ # Water depth below which it is considered to be 0 in the model minimum_allowed_height = 1.0e-3 # Water depth below which it is *stored* as 0 minimum_storable_height = 1.0e-5 # FIXME (Ole): Redefine this parameter to control maximal speeds in general # and associate it with protect_against_isolated_degenerate_timesteps = True maximum_allowed_speed = 0.0 # Maximal particle speed of water #maximum_allowed_speed = 1.0 # Maximal particle speed of water # Too large (100) creates 'flopping' water # Too small (0) creates 'creep' maximum_froude_number = 100.0 # To be used in limiters. ################################################################################ # Performance parameters used to invoke various optimisations ################################################################################ use_extensions = True # Use C-extensions use_psyco = True # Use psyco optimisations optimise_dry_cells = True # Exclude dry and still cells from flux computation optimised_gradient_limiter = True # Use hardwired gradient limiter use_edge_limiter = False # The edge limiter is better, but most runs have been # using vertex limiting. Validations passed with this # one True 9th May 2008, but many unit tests need # backward compatibility flag set FIXME(Ole). points_file_block_line_size = 500 # Number of lines read in from a points file # when blocking ################################################################################ # NetCDF-specific type constants. Used when defining NetCDF file variables. ################################################################################ netcdf_char = 'c' netcdf_byte = 'b' netcdf_int = 'i' netcdf_float = 'd' netcdf_float64 = 'd' netcdf_float32 = 'f' ################################################################################ # Dynamically-defined constants. ################################################################################ # Determine if we can read/write large NetCDF files netcdf_mode_w = 'w' netcdf_mode_a = 'a' netcdf_mode_r = 'r' # Code to set the write mode depending on # whether Scientific.IO supports large NetCDF files s = """ import os, tempfile from Scientific.IO.NetCDF import NetCDFFile filename = tempfile.mktemp('.nc') fid = NetCDFFile(filename, 'wl') fid.close() os.remove(filename) """ # Need to run in a separate process due an # error with older versions of Scientific.IO if sys.platform == 'win32': null = 'NUL' else: null = '/dev/null' cmd = 'python -c "%s" 2> %s' % (s, null) err = os.system(cmd) if err != 0: # The Python script s failed e.g. with a segfault # which means that large file support is # definitely not supported pass else: # Try the import within this process try: exec(s) except IOError: # NetCDFFile does not segfault but it does not # support large file support pass else: # Set the default mode to large file support #netcdf_mode_w = 'w4' # Future use of HDF5 netcdf_mode_w = 'wl' # Large NetCDF (new default 30/6/2009) #netcdf_mode_w = 'w' # Old style NetCDF used by OSG viewer