/[escript]/trunk/doc/examples/cookbook/example07a.py
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Contents of /trunk/doc/examples/cookbook/example07a.py

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Revision 3029 - (show annotations)
Fri May 21 02:01:37 2010 UTC (9 years, 6 months ago) by ahallam
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small updates and work on seismic code
1
2 ########################################################
3 #
4 # Copyright (c) 2009-2010 by University of Queensland
5 # Earth Systems Science Computational Center (ESSCC)
6 # http://www.uq.edu.au/esscc
7 #
8 # Primary Business: Queensland, Australia
9 # Licensed under the Open Software License version 3.0
10 # http://www.opensource.org/licenses/osl-3.0.php
11 #
12 ########################################################
13
14 __copyright__="""Copyright (c) 2009-2010 by University of Queensland
15 Earth Systems Science Computational Center (ESSCC)
16 http://www.uq.edu.au/esscc
17 Primary Business: Queensland, Australia"""
18 __license__="""Licensed under the Open Software License version 3.0
19 http://www.opensource.org/licenses/osl-3.0.php"""
20 __url__="https://launchpad.net/escript-finley"
21
22 ############################################################FILE HEADER
23 # example07a.py
24 # Antony Hallam
25 # Acoustic Wave Equation Simulation using displacement solution
26
27 #######################################################EXTERNAL MODULES
28 from esys.escript import *
29 from esys.finley import Rectangle
30 import sys
31 import os
32 # smoothing operator
33 from esys.escript.pdetools import Projector, Locator
34 from esys.escript.unitsSI import *
35 import numpy as np
36 import pylab as pl
37 import matplotlib.cm as cm
38 from esys.escript.linearPDEs import LinearPDE
39
40 ########################################################MPI WORLD CHECK
41 if getMPISizeWorld() > 1:
42 import sys
43 print "This example will not run in an MPI world."
44 sys.exit(0)
45
46 #################################################ESTABLISHING VARIABLES
47 # where to save output data
48 savepath = "data/example07a"
49 mkDir(savepath)
50 #Geometric and material property related variables.
51 mx = 1000. # model lenght
52 my = 1000. # model width
53 ndx = 400 # steps in x direction
54 ndy = 400 # steps in y direction
55 xstep=mx/ndx # calculate the size of delta x
56 ystep=my/ndy # calculate the size of delta y
57
58 c=380.0*m/sec # velocity of sound in air
59 csq=c*c #square of c
60 # Time related variables.
61 tend=1.5 # end time
62 h=0.001 # time step
63 # data recording times
64 rtime=0.0 # first time to record
65 rtime_inc=tend/20.0 # time increment to record
66 #Check to make sure number of time steps is not too large.
67 print "Time step size= ",h, "Expected number of outputs= ",tend/h
68
69 U0=0.005 # amplitude of point source
70 # want a spherical source in the middle of area
71 xc=[500,500] # with reference to mx,my this is the source location
72
73 ####################################################DOMAIN CONSTRUCTION
74 mydomain=Rectangle(l0=mx,l1=my,n0=ndx, n1=ndy) # create the domain
75 x=mydomain.getX() # get the node locations of the domain
76
77 ##########################################################ESTABLISH PDE
78 mypde=LinearPDE(mydomain) # create pde
79 mypde.setSymmetryOn() # turn symmetry on
80 mypde.setValue(D=1.) # set the value of D in the general form to 1.
81
82 ############################################FIRST TIME STEPS AND SOURCE
83 # define small radius around point xc
84 src_radius = 30
85 print "src_radius = ",src_radius
86 # set initial values for first two time steps with source terms
87 u=U0*(cos(length(x-xc)*3.1415/src_radius)+1)*whereNegative(length(x-xc)-src_radius)
88 u_m1=u
89 #plot source shape
90 cut_loc=[] #where the cross section of the source along x will be
91 src_cut=[] #where the cross section of the source will be
92 # create locations for source cross section
93 for i in range(ndx/2-ndx/10,ndx/2+ndx/10):
94 cut_loc.append(xstep*i)
95 src_cut.append([xstep*i,xc[1]])
96 # locate the nearest nodes to the points in src_cut
97 src=Locator(mydomain,src_cut)
98 src_cut=src.getValue(u) #retrieve the values from the nodes
99 # plot the x locations vs value and save the figure
100 pl.plot(cut_loc,src_cut)
101 pl.axis([xc[0]-src_radius*3,xc[0]+src_radius*3,0.,2.*U0])
102 pl.savefig(os.path.join(savepath,"source_line.png"))
103
104 ####################################################ITERATION VARIABLES
105 n=0 # iteration counter
106 t=0 # time counter
107 ##############################################################ITERATION
108 while t<tend:
109 g=grad(u); pres=csq*h*h*g # get current pressure
110 mypde.setValue(X=-pres,Y=(2.*u-u_m1)) # set values in pde
111 u_p1 = mypde.getSolution() # get the new displacement
112 u_m1=u; u=u_p1 # shift values back one time step for next iteration
113 # save current displacement, acceleration and pressure
114 if (t >= rtime):
115 saveVTK(os.path.join(savepath,"ex07a.%i.vtu"%n),displacement=length(u),tensor=pres)
116 rtime=rtime+rtime_inc #increment data save time
117 # increment loop values
118 t=t+h; n=n+1
119 print n,"-th time step t ",t

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