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<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=152530102-11032010>Here is my reply to John.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> Duclaux, Guillaume (CESRE, Kensington)
<BR><B>Sent:</B> Thursday, 11 March 2010 9:06 AM<BR><B>To:</B> 'John
Naliboff'<BR><B>Cc:</B> nicolas.riel@free.fr<BR><B>Subject:</B> RE: [CIG-LONG]
Convergence issues with long-term extension models<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV class=Section1>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Hi
John,<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">There’s a hidden
magical compressibility function in Gale/Underworld.
<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">In the component part
of your script, create a new shape (let say called “compressibleShape”) at the
top of the model, then define it’s rheology and mechanical
properties.<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">You can create a new
viscosity. As you suggested, a low viscosity works. You may have to do some
testing. In case your model resolution is too low, you’ll find an instability
between the compressible layer and the upper crust with particles “flying’
upward. <o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<struct name="compressibleViscous"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<param
name="Type">MaterialViscosity</param><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<param name="eta0">1e-4</param><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
</struct><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Then define the
compressibility function:<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><struct
name="compresibility"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<param name="Type">Compressible</param><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<param
name="GeometryMesh">mesh-linear</param><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<param
name="StiffnessMatrix">c_matrix</param><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<param
name="Swarm">picIntegrationPoints</param><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<param
name="oneOnLambda">10.0</param>
<!—this is the ‘compressibility factor, 1/lambda. It has to be set between 0
and 10. As a rule of thumb, the larger 1/lambda (ie 10), the more compressible
</SPAN></FONT><FONT face=Wingdings color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Wingdings">à</SPAN></FONT><FONT
face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
</struct><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">and apply the
compressible material properties to the compressibleShape
material:<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<struct name="compressibleRheology"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<param
name="Type">RheologyMaterial</param><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<param
name="Shape">compressibleShape</param><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<param name="density">XX</param> <!—do some testing, but 0
works usually fine </SPAN></FONT><FONT face=Wingdings color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Wingdings">à</SPAN></FONT><FONT
face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<list name="Rheology"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<param>compressibleViscous</param><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<!-- <param>storeViscosity</param><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<param>storeStress</param> </SPAN></FONT><FONT face=Wingdings
color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Wingdings">à</SPAN></FONT><FONT
face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"> <!—this is
optional, dunno if you’re outputting Stress and Viscosity for the particles
</SPAN></FONT><FONT face=Wingdings color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Wingdings">à</SPAN></FONT><FONT
face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
</list><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
<param
name="Compressible">compresibility</param><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">
</struct><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Ge it a shot, and let
me know if you have any trouble with this function.<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Cheers<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Gilly<o:p></o:p></SPAN></FONT></P>
<DIV>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">________________________________________________</SPAN></FONT><FONT
color=navy><SPAN style="COLOR: navy"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face="Times New Roman" color=navy size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: navy"> <o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Dr Guillaume
Duclaux</SPAN></FONT><FONT color=navy><SPAN
style="COLOR: navy"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">CSIRO Earth Science and
Resource Engineering</SPAN></FONT><FONT color=navy><SPAN
style="COLOR: navy"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Visiting address: ARRC,
26 Dick Perry Av., <st1:place w:st="on"><st1:City
w:st="on">Kensington</st1:City> <st1:State w:st="on">WA</st1:State></st1:place>
6151</SPAN></FONT><FONT color=navy><SPAN
style="COLOR: navy"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Postal address:
<st1:address w:st="on"><st1:Street w:st="on">PO Box 1130</st1:Street>, <st1:City
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6102, <st1:country-region w:st="on"><st1:place
w:st="on">Australia</st1:place></st1:country-region></SPAN></FONT><FONT
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<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Ph: + 61 8 6436
8728 Fax: + 61 8 6436 8555 Web: <A
href="http://www.csiro.au">www.csiro.au</A></SPAN></FONT><FONT color=navy><SPAN
style="COLOR: navy"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face="Times New Roman" color=navy size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: navy"> </SPAN></FONT><o:p></o:p></P></DIV>
<DIV>
<DIV class=MsoNormal style="TEXT-ALIGN: center" align=center><FONT
face="Times New Roman" size=3><SPAN lang=EN-US style="FONT-SIZE: 12pt">
<HR tabIndex=-1 align=center width="100%" SIZE=2>
</SPAN></FONT></DIV>
<P class=MsoNormal><B><FONT face=Tahoma size=2><SPAN lang=EN-US
style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Tahoma">From:</SPAN></FONT></B><FONT
face=Tahoma size=2><SPAN lang=EN-US
style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma"> John Naliboff
[mailto:jbnaliboff@gmail.com] <B><SPAN style="FONT-WEIGHT: bold">On Behalf Of
</SPAN></B>John Naliboff<BR><B><SPAN style="FONT-WEIGHT: bold">Sent:</SPAN></B>
Thursday, 11 March 2010 8:29 AM<BR><B><SPAN
style="FONT-WEIGHT: bold">To:</SPAN></B> Duclaux, Guillaume (CESRE,
Kensington)<BR><B><SPAN style="FONT-WEIGHT: bold">Cc:</SPAN></B>
nicolas.riel@free.fr<BR><B><SPAN style="FONT-WEIGHT: bold">Subject:</SPAN></B>
Re: [CIG-LONG] Convergence issues with long-term extension
models</SPAN></FONT><SPAN lang=EN-US><o:p></o:p></SPAN></P></DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">Hi again Gilly,<o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">Apologies for the second email.
<o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">When implementing the compressible layer, did you simply
specify a low-viscosity/low-density region and then not subtract the hydrostatic
term from this region (i.e. hydrostatic term still subtracted from the
lithosphere)? <o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">This is the only way I could think of to create a
quasi-compressible layer with the current version of Gale (1.4.1). If used
another method to create the compressible layer, however, any tips would be
great!<o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">Cheers,<o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">John<o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"> <o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P></DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P>
<DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">On Mar 10, 2010, at 9:32 AM, John Naliboff
wrote:<o:p></o:p></SPAN></FONT></P></DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><BR><BR><o:p></o:p></SPAN></FONT></P>
<DIV
style="WORD-WRAP: break-word; webkit-nbsp-mode: space; webkit-line-break: after-white-space">
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">Hi Gilly,<o:p></o:p></SPAN></FONT></P>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">Thanks for the suggestion and I'll give the compressible
layer a shot today!<o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">John<o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P></DIV>
<DIV>
<DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">On Mar 10, 2010, at 12:20 AM, <<A
href="mailto:Guillaume.Duclaux@csiro.au">Guillaume.Duclaux@csiro.au</A>>
wrote:<o:p></o:p></SPAN></FONT></P></DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><BR><BR><o:p></o:p></SPAN></FONT></P><U1:SMARTTAGTYPE
name="country-region"
namespaceuri="urn:schemas-microsoft-com:office:smarttags"><U1:SMARTTAGTYPE
name="Street"
namespaceuri="urn:schemas-microsoft-com:office:smarttags"><U1:SMARTTAGTYPE
name="address"
namespaceuri="urn:schemas-microsoft-com:office:smarttags"><U1:SMARTTAGTYPE
name="State"
namespaceuri="urn:schemas-microsoft-com:office:smarttags"><U1:SMARTTAGTYPE
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<DIV
style="WORD-WRAP: break-word; webkit-nbsp-mode: space; webkit-line-break: after-white-space"
vlink="blue" link="blue">
<P class=MsoNormal><FONT face=Arial color=blue size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial">Hi
John,</SPAN></FONT><U1:P></U1:P><o:p></o:p></P>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"> <U1:P></U1:P><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=blue size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial">Have you tried adding a
compressible layer at the surface of the
model?<U1:P></U1:P></SPAN></FONT><o:p></o:p></P>
<P class=MsoNormal><FONT face=Arial color=blue size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial"><U1:P> </U1:P></SPAN></FONT><o:p></o:p></P>
<P class=MsoNormal><FONT face=Arial color=blue size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial">Nicolas Riel and I ran
some extension models recently and found out that the only way to achieve large
deformation is to use such compressible
layer.<U1:P></U1:P></SPAN></FONT><o:p></o:p></P>
<P class=MsoNormal><FONT face=Arial color=blue size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial"><U1:P> </U1:P></SPAN></FONT><o:p></o:p></P>
<P class=MsoNormal><FONT face=Arial color=blue size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial">The initial geometry of
the model is as follow with the compressible layer in
red:<U1:P></U1:P></SPAN></FONT><o:p></o:p></P>
<P class=MsoNormal><FONT face=Arial color=blue size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial"><U1:P> </U1:P></SPAN></FONT><o:p></o:p></P>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><image003.jpg><U1:P></U1:P><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><U1:P> </U1:P><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">so you can extend the model quite extensively (the
compressible has been removed for
visualisation)<U1:P></U1:P><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"> <U1:P></U1:P><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=blue size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial"><image004.jpg><U1:P></U1:P></SPAN></FONT><o:p></o:p></P>
<P class=MsoNormal><FONT face=Arial color=blue size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial"><U1:P> </U1:P></SPAN></FONT><o:p></o:p></P>
<P class=MsoNormal><FONT face=Arial color=blue size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial">Give it a
go!<U1:P></U1:P></SPAN></FONT><o:p></o:p></P>
<P class=MsoNormal><FONT face=Arial color=blue size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial"><U1:P> </U1:P></SPAN></FONT><o:p></o:p></P>
<P class=MsoNormal><FONT face=Arial color=blue size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial">Cheers<U1:P></U1:P></SPAN></FONT><o:p></o:p></P>
<P class=MsoNormal><FONT face=Arial color=blue size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial"><U1:P> </U1:P></SPAN></FONT><o:p></o:p></P>
<P class=MsoNormal><FONT face=Arial color=blue size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial">gilly</SPAN></FONT><U1:P></U1:P><o:p></o:p></P>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"> <U1:P></U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">________________________________________________</SPAN></FONT><U1:P></U1:P><o:p></o:p></P>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"> <U1:P></U1:P><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Dr Guillaume
Duclaux</SPAN></FONT><U1:P></U1:P><o:p></o:p></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">CSIRO Earth Science and Resource
Engineering</SPAN></FONT><U1:P></U1:P><o:p></o:p></P>
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<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"> <U1:P></U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><U1:P> </U1:P><o:p></o:p></SPAN></FONT></P>
<DIV class=MsoNormal style="TEXT-ALIGN: center" align=center><FONT
face="Times New Roman" size=3><SPAN lang=EN-US style="FONT-SIZE: 12pt">
<HR tabIndex=-1 align=center width="100%" SIZE=2>
</SPAN></FONT></DIV>
<P class=MsoNormal style="MARGIN-BOTTOM: 12pt"><B><FONT face=Tahoma size=2><SPAN
lang=EN-US
style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Tahoma">From:</SPAN></FONT></B><FONT
face=Tahoma size=2><SPAN lang=EN-US
style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma"> <A
href="mailto:cig-long-bounces@geodynamics.org">cig-long-bounces@geodynamics.org</A>
[mailto:cig-long-bounces@geodynamics.org] <B><SPAN style="FONT-WEIGHT: bold">On
Behalf Of </SPAN></B>John Naliboff<BR><B><SPAN
style="FONT-WEIGHT: bold">Sent:</SPAN></B> Wednesday, 10 March 2010 3:03
PM<BR><B><SPAN style="FONT-WEIGHT: bold">To:</SPAN></B> <A
href="mailto:cig-long@geodynamics.org">cig-long@geodynamics.org</A><BR><B><SPAN
style="FONT-WEIGHT: bold">Subject:</SPAN></B> [CIG-LONG] Convergence issues with
long-term extension models</SPAN></FONT><o:p></o:p></P><U1:P></U1:P>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">Hello all, <U1:P></U1:P><o:p></o:p></SPAN></FONT></P>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><U1:P> </U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">I'm hoping to get some input on convergence problems I'm
having with 2D long-term extension
models.<U1:P></U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><U1:P> </U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">The models are designed following Wijns et al. 2005
(EPSL), who modeled extension of a brittle upper crust overlying a viscous lower
crust using Underworld. The initial geometry is 160 km (width) x 60 km
(depth) and the upper crust follows a yielding law similar to the DruckerPrager
yield criterion. The boundary conditions are free-slip on all sides,
although a weak, low-density layer is present above the upper crust (i.e. top of
lithosphere should behave in a similar fashion to a true free-surface).
Extension is driven by a fixed velocity of 3 cm/yr applied to the right side of
the 2D box. The models in the paper are run up to roughly 80% extension (~ 4
Myr). <U1:P></U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><U1:P> </U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">The simulations I'm running mimic the models above very
closely, although I'm using an upper free-surface rather than placing a weak,
low-density layer above the upper crust and specifying free-slip on the top
boundary.<U1:P></U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><U1:P> </U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">In short, the problem I'm encountering reproducing the
long-term extension models is that my simulations stop converging after ~
1-2 Myr (~ 25%-40% extension). In terms of specific error messages, the
problem is almost always related to the Stokes Uzawa Solver
(ex: </SPAN></FONT><SPAN class=apple-style-span><I><FONT face=Helvetica
size=2><SPAN
style="FONT-SIZE: 10pt; FONT-STYLE: italic; FONT-FAMILY: Helvetica">uzawaRhsScale
has illegal value 'inf', etc</SPAN></FONT></I></SPAN><SPAN
class=apple-style-span><FONT face=Helvetica size=4><SPAN
style="FONT-SIZE: 13.5pt; FONT-FAMILY: Helvetica">).</SPAN></FONT></SPAN><U1:P></U1:P><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><U1:P> </U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">In terms of the model output, by 1-2 Myr very large
strain rate gradients have developed at the model surface roughly following
horst and grabben structures. I think this may be the source of the
convergence issue, but at this point I'm really not
certain.<U1:P></U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><U1:P> </U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">After initially having convergence issues with a
resolution of 1 km and 30 particles per cell (ppc), I systematically increased
the resolution up 0.25 km with 60 ppc, but all the models still stopped
converging between 1-2 Myr.<U1:P></U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">I also tried decreasing the time step by 2 (dtFactor =
0.5) and turning off the pressure and velocity interpolation onto the new mesh,
neither of which had any significant effect on the total run time before the
models stopped converging. In all of the cases above I used the MUMPS
solver, which performed better than the default
solver.<U1:P></U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><U1:P> </U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">The convergence issue is also not likely related to the
specific upper crustal yielding rheology, as I've tried both DruckerPrager,
VonMises and the yielding law used in the Wijns et al.
models.<U1:P></U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><U1:P> </U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">Finally, I tried using a free-slip top boundary with a
weak, low-density layer above the upper crust, but this produced a whole
different set of issues.<U1:P></U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><U1:P> </U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">Thanks in advance to anyone who has some ideas/input on
the convergence issues and I've attached a sample input file (resolution = 0.5
km, ppc = 60) if that helps at
all.<U1:P></U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><U1:P> </U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">Cheers,<U1:P></U1:P><o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">John
Naliboff<U1:P></U1:P><o:p></o:p></SPAN></FONT></P></DIV></DIV></DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P></DIV></DIV></DIV></U1:SMARTTAGTYPE></U1:SMARTTAGTYPE></U1:SMARTTAGTYPE></U1:SMARTTAGTYPE></U1:SMARTTAGTYPE></U1:SMARTTAGTYPE>
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