This is an old revision of the document!

Warning: Declaration of syntax_plugin_mathpublish::handle($match, $state, $pos, &$handler) should be compatible with DokuWiki_Syntax_Plugin::handle($match, $state, $pos, Doku_Handler $handler) in /home/np29546/public_html/elmerice/wiki/lib/plugins/mathpublish/syntax.php on line 0

Warning: Declaration of syntax_plugin_mathpublish::render($mode, &$R, $data) should be compatible with DokuWiki_Syntax_Plugin::render($format, Doku_Renderer $renderer, $data) in /home/np29546/public_html/elmerice/wiki/lib/plugins/mathpublish/syntax.php on line 0

User Function Coulomb Friction Law

General Informations

  • USF Fortran File: USF_Sliding.f90
  • USF Name: Friction_Coulomb
  • Required Input Variable(s): A Flow Solution in Flow Solution Name, Normal Vector

General Description

The file USF_Sliding.f90 contains two user functions to apply non-linear friction at the base of glacier.

The first user function (Sliding_Weertman) is a non-linear Weertman-type friction law and is described here. The second user function (Friction_Coulomb) is a non-linear water pressure dependant friction law, as proposed by Schoof (2005) and Gagliardini et al. (2007), and is presented in this page.

SIF contents

The required keywords in the SIF file for this user function are:

!!! Bedrock Boundary Condition 
Boundary Condition 1
  Target Boundaries = 1

  Normal-Tangential Velocity = Logical True
  Flow Force BC = Logical True

  Velocity 1 = Real 0.0
  Slip Coefficient 2 =  Variable Coordinate 1
    Real Procedure "./USF_Sliding" "Friction_Coulomb"
  Slip Coefficient 3 =  Variable Coordinate 1
    Real Procedure "./USF_Sliding" "Friction_Coulomb"
  !! Parameters needed for the Coulomb Friction Law
  Friction Law Sliding Coefficient = Real 4.1613e5  
  Friction Law Post-Peak Exponent  = Real 1.0      !(q=1)
  Friction Law Maximum Value = Real 1.0            !(C=1)
  Friction Law PowerLaw Exponent = Real 3.0        !(m = n = 3 Glen's law) 
  Friction Law Linear Velocity = Real 0.01         !(=1m/a dans un premier temps)


An example of the usage of the user function Friction_Weertman TODO


When this friction law is used, it can be cited using the following reference:
Gagliardini O., D. Cohen, P. Råback and T. Zwinger, 2007. Finite-Element Modeling of Subglacial Cavities and Related Friction Law. J. of Geophys. Res., Earth Surface, 112, F02027.

userfunctions/coulomb.1352944069.txt.gz · Last modified: 2012/11/15 01:47 by gag
CC Attribution-Share Alike 4.0 International Valid CSS Driven by DokuWiki do yourself a favour and use a real browser - get firefox!! Recent changes RSS feed Valid XHTML 1.0