[CIG-LONG] CIG-LONG Digest, Vol 45, Issue 12

[Patrice Rey]

Hi Nicolas

The dimension of A (the pre-stress constant) is MPa^-n . s^-1, or ... 10^(-6*n) . s^-1; a bit messy and a common source of errors.

Common values I use for the continental crust: (5 10^-6) .10^-(6*n); for the lower crust: 8 .10^-(6*n), and for the mantle: 70000.10^-(6*n)

The scaling factor of A is : (StressScalingFactor^-n) / TimeScalingFactor.

Cheers

Patrice



On 19/08/2010, at 5:00 AM, cig-long-request at geodynamics.org wrote:
> 
> 
> ------------------------------
> 
> Message: 3
> Date: Wed, 18 Aug 2010 17:20:19 +0200
> From: Nicolas RIEL <nicolas.riel at free.fr>
> Subject: [CIG-LONG] Non-Newtonian rheology scaling !
> To: cig-long at geodynamics.org
> Message-ID:
> 	<AANLkTimF7AA1jjOfbcz+QwFTXTpJp-uunMLPp+Jh2Fjn at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> Hi,
> 
> I'm encountering some problems when scaling the "A" (creeping parameter) for
> the non-newtonian rheology.
> In gale user manual (2.2.8.2) it is said that the unit of A parameter is *
> s(-1/n).Pa(-1)
> *For other authors the unit of this parameter is most of the time in *
> Pa(-n).s(-1)* or *Pa.s(1/n).*
> 
> I will take an example in order to understand :
> 
> 
> A = 262800* Pa.s(1/n)*
> n = 4*
> 
> *If I want to translate this value for gale, first I have to change the
> units for *s(-1/n).Pa(-1) *by multplying with ^(-1) ?
> 
> Then A unscaled becomes for gale 262800^(-1) = 3.8051e-6
> 
> Based on that and following gale user manual A scaled for gale is 3.8051e-6
> * (10e25)^(1/n) = 6.7574
> However in the dyke example the scaling of A is around 1e-12.
> 
> I'm wondering if there a mistake for the given scaling equation. Maybe this
> equation should be Anew = Aold(10e25)^(-1/n) ?
> 
> When I use this, I obtain Anew = 2.1368e-12 and this works
> 
> Do you have any suggestions about this ?
> 
> Nicolas Riel
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> End of CIG-LONG Digest, Vol 45, Issue 12
> ****************************************

Associate Professor Patrice F. Rey
EarthByte Research Group
School of Geosciences
The University of Sydney
+61 2 9351 2067
patrice.rey at mac.com
patrice.rey at sydney.edu.au






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