visco_plastic_yield_strain_weakening_full_strain_tensor.prm

# Global parameters
set Dimension                              = 2
set Start time                             = 0
set End time                               = 1e2
set Use years in output instead of seconds = true
set Nonlinear solver scheme                = iterated Stokes
set Max nonlinear iterations               = 1
set Number of cheap Stokes solver steps    = 0
set Output directory                       = visco_plastic_yield_strain_weakening_full_strain_tensor
set Timing output frequency                = 1

# Model geometry (100x100 km, 10 km spacing)
subsection Geometry model
  set Model name = box
  subsection Box
    set X repetitions = 10
    set Y repetitions = 10
    set X extent      = 100e3
    set Y extent      = 100e3
  end
end

# Mesh refinement specifications 
subsection Mesh refinement
  set Initial adaptive refinement        = 0
  set Initial global refinement          = 0
  set Time steps between mesh refinement = 0
end


# Boundary classifications (fixed T boundaries, prescribed velocity) 
subsection Model settings
  set Fixed temperature boundary indicators   = bottom, top, left, right
  set Prescribed velocity boundary indicators = bottom y: function, top y: function, left x: function, right x: function
end

# Velocity on boundaries characterized by functions
subsection Boundary velocity model
  subsection Function
    set Variable names      = x,y
    set Function constants  = m=0.0005, year=1
    set Function expression = if (x<50e3 , -1*m/year, 1*m/year); if (y<50e3 , 1*m/year, -1*m/year);
  end
end

# Temperature boundary and initial conditions
subsection Boundary temperature model
  set Model name = box
  subsection Box
    set Bottom temperature = 273
    set Left temperature   = 273
    set Right temperature  = 273
    set Top temperature    = 273
  end
end
subsection Initial temperature model
  set Model name = function
  subsection Function
    set Function expression = 273
  end
end

# Compositional fields used to track finite strain
subsection Compositional fields
  set Number of fields = 4
  set Names of fields = s11, s12, s21, s22
end

# The compositional fields have an initial value 0 or 0.5
subsection Initial composition model
  set Model name = function
  subsection Function
    set Variable names      = x,y
    set Function expression = 0.5; 0; 0; 0.5;
  end
end

# Boundary composition specification
subsection Boundary composition model
  set Model name = initial composition
end

# Material model (values for background material and strain fields)
subsection Material model
  set Model name = visco plastic
  subsection Visco Plastic
    set Reference strain rate = 1.e-16
    set Viscous flow law = dislocation
    set Prefactors for dislocation creep = 5.e-23
    set Stress exponents for dislocation creep = 1.0
    set Activation energies for dislocation creep = 0.
    set Activation volumes for dislocation creep = 0.
    set Yield mechanism = drucker
    set Angles of internal friction = 0.
    set Cohesions = 1.e6
    set Use strain weakening = true
    set Use finite strain tensor = true
    set Start strain weakening intervals = 0.
    set End strain weakening intervals = 1.0
    set Cohesion strain weakening factors = 0.5
    set Friction strain weakening factors = 0.5
  end
end

# Gravity model
subsection Gravity model
  set Model name = vertical
  subsection Vertical
    set Magnitude = 10.0
  end
end

# Post processing
subsection Postprocess
  set List of postprocessors = velocity statistics, mass flux statistics
end