/[escript]/trunk/modellib/py_src/flow.py
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Annotation of /trunk/modellib/py_src/flow.py

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Revision 820 - (hide annotations)
Mon Aug 28 06:55:36 2006 UTC (14 years, 3 months ago) by gross
File MIME type: text/x-python
File size: 4408 byte(s)
make the modelframe test run
1 jgs 144 # $Id$
2    
3 elspeth 628 __copyright__=""" Copyright (c) 2006 by ACcESS MNRF
4     http://www.access.edu.au
5     Primary Business: Queensland, Australia"""
6     __license__="""Licensed under the Open Software License version 3.0
7     http://www.opensource.org/licenses/osl-3.0.php"""
8    
9 jgs 149 from esys.escript import *
10     from esys.escript.modelframe import Model,IterationDivergenceError
11     from esys.escript.linearPDEs import LameEquation
12 jgs 144
13     class SteadyIncompressibleFlow(Model):
14 jgs 147 """
15 jgs 144
16 jgs 149 M{-\left(\eta\left(v_{i,j}+v_{j,i}\right)\right)_{,j}+p_{,i}=F_i}
17    
18     M{\sigma_{ij}=2\eta D_{ij}-p\,\delta_{ij}}
19 jgs 144
20 jgs 149 M{D_{ij}=\frac{1}{2}\left( v_{j,i} + v_{i,j }\right)}
21    
22     M{v_{k,k} = 0}
23 jgs 144
24     """
25    
26     def __init__(self,debug=False):
27 jgs 149 """
28     set up model
29     """
30 jgs 144 Model.__init__(self,debug=debug)
31     self.declareParameter(domain=None, \
32     velocity=0., \
33     pressure=0., \
34 jgs 147 viscosity=1., \
35 jgs 144 internal_force=0., \
36 jgs 147 location_prescribed_velocity=Data(), \
37     prescribed_velocity=Data(), \
38 gross 820 rel_tol=1.e-3,abs_tol=0.,max_iter=10,relaxation=0.0001)
39 jgs 144 self.__iter=0
40    
41 jgs 147 def doInitialization(self):
42 jgs 149 """
43     initialize model
44     """
45 jgs 147 self.__p_old=None
46     self.__p_very_old=None
47     self.__dt_old=None
48 jgs 144 self.__pde=LameEquation(self.domain)
49 gross 820 self.__pde.setSolverMethod(LameEquation.DIRECT)
50 jgs 144
51     def stress(self):
52 jgs 149 """
53     returns current stress"""
54 jgs 147 return 2*self.viscosity*self.stretching-self.pressure*kronecker(self.domain)
55 jgs 144
56     def stretching(self):
57 jgs 149 """
58     returns stertching tensor
59     """
60 jgs 144 g=grad(self.velocity)
61     return (g+transpose(g))/2
62 jgs 147
63     def doStepPreprocessing(self,dt):
64 jgs 144 """
65 jgs 149 step up pressure iteration
66 jgs 144
67 jgs 149 if run within a time dependend problem extrapolation of pressure from previous time steps is used to
68     get an initial guess (that needs some work!!!!!!!)
69 jgs 144 """
70 jgs 147 self.__iter=0
71     self.__diff=1.e40
72     if not self.__p_old==None:
73     if self.__p_very_old==None:
74     self.pressure=self.__p_old
75     else:
76     self.pressure=(1.+dt/self.__dt_old)*self.__p_old-dt/self.__dt_old*self.__p_very_old
77 jgs 144
78 jgs 147 def doStep(self,dt):
79 jgs 144 """
80    
81 jgs 149 performs an iteration step of the penalty method.
82     IterationDivergenceError is raised if pressure error cannot be reduced or max_iter is reached.
83 jgs 144
84     """
85     penalty=self.viscosity/self.relaxation
86 jgs 147 self.__pde.setValue(lame_mu=self.viscosity, \
87     lame_lambda=penalty, \
88     F=self.internal_force, \
89     sigma=self.pressure*kronecker(self.__pde.getDomain()), \
90     r=self.prescribed_velocity, \
91     q=self.location_prescribed_velocity)
92     self.__pde.setTolerance(self.rel_tol/10.)
93     self.velocity=self.__pde.getSolution()
94 jgs 144 update=penalty*div(self.velocity)
95     self.pressure=self.pressure-update
96 jgs 147 self.__diff,diff_old=Lsup(update),self.__diff
97     self.__iter+=1
98     self.trace("velocity range %e:%e"%(inf(self.velocity),sup(self.velocity)))
99     self.trace("pressure range %e:%e"%(inf(self.pressure),sup(self.pressure)))
100     self.trace("pressure correction: %e"%self.__diff)
101     if self.__iter>2 and diff_old<self.__diff:
102     self.trace("Pressure iteration failed!")
103 jgs 144 raise IterationDivergenceError,"no improvement in pressure iteration"
104 jgs 147 if self.__iter>self.max_iter:
105     raise IterationDivergenceError,"Maximum number of iterations steps reached"
106 jgs 144
107 jgs 147 def terminateIteration(self):
108     """iteration is terminateIterationd if relative pressure change is less then rel_tol"""
109     return self.__diff<=self.rel_tol*Lsup(self.pressure)+self.abs_tol
110 jgs 144
111 jgs 147 def doStepPostprocessing(self,dt):
112     self.__dt_old=dt
113     self.__p_old,self.__p_very_old=self.pressure,self.__p_old

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