# Contents of /trunk/doc/examples/cookbook/example07a.py

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Thu May 6 01:20:46 2010 UTC (10 years, 3 months ago) by ahallam
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```Updates to wave equation examples. Pressure wave examples should be completed now. Working on seismic wave examples. Cookbook chapter for pressure wave examples also added.
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 1 2 ######################################################## 3 # 4 # Copyright (c) 2009-2010 by University of Queensland 5 # Earth Systems Science Computational Center (ESSCC) 6 7 # 8 # Primary Business: Queensland, Australia 9 # Licensed under the Open Software License version 3.0 10 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 20 __url__= 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/example07" 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= rtime): 115 saveVTK(os.path.join(savepath,"ex07b.%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