subsection Material model
  set Model name = simple

  subsection Simple model
    set Viscosity                     = 1e2
    set Thermal expansion coefficient = 0
    set Density differential for compositional field 1 = -10
  end
end

subsection Initial composition model
  set Model name = function

  subsection Function
    set Variable names      = x,z
    set Function constants  = pi=3.14159
    set Function expression = if( (z>0.2+0.02*cos(pi*x/0.9142)) , 0 , 1 )
  end
end
