I am trying to get columb-friction sliding running on a model of a small'ish glacier I am currently working on.

I am using the ParStokes solver but it keeps diverging when I activate the CF law. From reading on the forum I have been trying to write a mask to restrict sliding in areas with less then 10 meters of ice. The model contains some areas that are ice free where I set the ice to 1 m,

Code: Select all

```
Top Surface = Variable ZsDEM, bedrockDEM
Real MATC "if (tx(0)>tx(1)+1.0) {tx(0)} else {tx(1)+1.0}"
```

This syntax should set Flow Solution 1 equal zero if the ice is less then 10 meters.

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```
Flow Solution 1 = Real 0.0
Flow Solution 1 Condition = Variable ZsDEM, bedrockDEM
Real MATC "-1*(tx(0)-tx(1)-10.0)"
```

My full bedrock BC is,

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```
!! bedrock:
Boundary Condition 3
Name = "bedrock"
Height = Real 0.0
Bottom Surface = Equals bedrockDEM
Normal-Tangential Velocity = Logical True
Flow Force BC = Logical True
Flow Solution 1 = Real 0.0
Flow Solution 1 Condition = Variable ZsDEM, bedrockDEM
Real MATC "-1*(tx(0)-tx(1)-10.0)"
Velocity 1 = REal 0.0
Velocity 1 Condition = Variable ZsDEM, bedrockDEM
Real MATC "-1*(tx(0)-tx(1)-10.0)"
Velocity 2 = REal 0.0
Velocity 2 Condition = Variable ZsDEM, bedrockDEM
Real MATC "-1*(tx(0)-tx(1)-10.0)"
Flow Solution 2 = REal 0.0
Flow Solution 2 Condition = Variable ZsDEM, bedrockDEM
Real MATC "-1*(tx(0)-tx(1)-10.0)"
Slip Coefficient 2 = Variable Coordinate 1
Real Procedure "ElmerIceUSF" "Friction_Coulomb"
Slip Coefficient 3 = Variable Coordinate 1
Real Procedure "ElmerIceUSF" "Friction_Coulomb"
!! Parameters needed for the Coulomb Friction Law
Friction Law Sliding Coefficient = Real 4.1613e5
Friction Law Post-Peak Exponent = Real 1.0
Friction Law Maximum Value = Real 1.0
Friction Law PowerLaw Exponent = Real 3.0
Friction Law Linear Velocity = Real 0.01
End
```

Christian