viscoelastic_fixed_elastic_time_step.prm

#  Global parameters
set Dimension                              = 2
set Start time                             = 0
set End time                               = 1e3
set Use years in output instead of seconds = true
set Linear solver tolerance                = 1e-7
set Nonlinear solver scheme                = IMPES
set Number of cheap Stokes solver steps    = 500
set CFL number                             = 0.5
set Maximum time step                      = 1000
set Output directory                       = viscoelastic_fixed_elastic_time_step
set Timing output frequency                = 1
set Pressure normalization                 = surface
set Surface pressure                       = 0.

# Model geometry (100x100 km, 5 km spacing)
subsection Geometry model
  set Model name = box

  subsection Box
    set X repetitions = 20
    set Y repetitions = 20
    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
subsection Model settings
  set Fixed composition boundary indicators   = bottom, top, left, right
  set Fixed temperature boundary indicators   = bottom, top, left, right
  set Prescribed velocity boundary indicators = bottom y:function, right x:function 
  set Free surface boundary indicators        = 
  set Tangential velocity boundary indicators = top, left 
  set Zero velocity boundary indicators       = 
  set Enable elasticity                       = true
end

subsection Boundary velocity model
  subsection Function
    set Variable names      = x,y
    set Function constants  = cm=0.01, year=1, vel=3.154
    set Function expression = if (x>50e3 , vel*cm/year, 0.); if (y<50e3 , vel*cm/year, 0.); 
  end
end

# Number and name of compositional fields
subsection Compositional fields
  set Number of fields = 3
  set Names of fields  = s11, s22, s12
end

# Spatial domain of different compositional fields
subsection Initial composition model
  set Model name = function
  subsection Function
    set Variable names      = x,y
    set Function constants  = 
    set Function expression = 0; 0; 0;
  end
end

# Composition boundary conditions
subsection Boundary composition model
  set Model name = initial composition
end

# Temperature boundary and initial conditions
subsection Boundary temperature model
  set Model name = box
  subsection Box
    set Bottom temperature = 293
    set Left temperature   = 293
    set Right temperature  = 293
    set Top temperature    = 293
  end
end
subsection Initial temperature model
  set Model name = function
  subsection Function
    set Function expression = 293
  end
end

# Material model
subsection Material model

  set Model name = viscoelastic

  subsection Viscoelastic
    set Densities                   = 2800
    set Viscosities                 = 1.e21
    set Elastic shear moduli        = 1.e10
    set Use fixed elastic time step = true
    set Fixed elastic time step     = 1e3
    set Use stress averaging        = false
    set Viscosity averaging scheme  = harmonic
  end

end

# Gravity model
subsection Gravity model
  set Model name = vertical
  subsection Vertical
    set Magnitude = 0.
  end
end

# Element types
subsection Discretization
  set Composition polynomial degree     = 2
  set Stokes velocity polynomial degree = 2
  set Temperature polynomial degree     = 1
end

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

# Termination criteria
subsection Termination criteria
 set Termination criteria = end time
end