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userfunctions:coulomb [2015/11/26 15:44]
gag [General Description]
userfunctions:coulomb [2015/12/02 12:24] (current)
gag [General Description]
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   * ''​Friction Law Linear Velocity''​ -> <​m>​u_{t0}</​m>  ​   * ''​Friction Law Linear Velocity''​ -> <​m>​u_{t0}</​m>  ​
  
-The effective pressure is defined as <m>N = -sigma_{nn} -p_w</​m>, ​ where <​m>​sigma_{nn}</​m>​ is the normal Cauchy stress and <​m>​p_w</​m>​ the water pressure. ​Hereat time t+dt, the normal Cauchy stress is estimated from the stress computed at time t. The water pressure is prescribed as an ''​External Pressure''​ (Negative - Compressive convention, and therefore ​the water pressure is the opposite of the '​External Pressure'​). ​+The effective pressure is defined as <m>N = -sigma_{nn} -p_w</​m>, ​ where <​m>​sigma_{nn}</​m>​ is the normal Cauchy stress and <​m>​p_w</​m>​ the water pressure. ​If a variable ''​Effective Pressure''​ existsit is used to evaluate directly <​m>​N</​m>​. Else, the normal Cauchy stress is estimated from the stress computed at previous timestep. The water pressure is prescribed as an ''​External Pressure''​ (Negative - Compressive convention, and therefore '​External Pressure' ​should be equal to the opposite of the water pressure in the sif). 
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 ==== Examples ==== ==== Examples ====
-An example of the usage of the user function ​//​Friction_Coulomb// ​TODO +The Coulomb friction law is tested in ''​[ELMER_TRUNK]/elmerice/​Tests/​Friction_Coulomb''​ with a direct input of the effective pressure and ''​[ELMER_TRUNK]/elmerice/Tests/​Friction_Coulomb_Pw''​ with the effective pressure computed from the stress and a prescribed water pressure.  ​
  
  
userfunctions/coulomb.1448552677.txt.gz ยท Last modified: 2015/11/26 15:44 by gag
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