[nonlinearsolver] block

The block [nonlinearsolver] is used for the newton-raphson nonlinear iteration. This block's layout looks as follows:

[nonlinearsolver]
  type=nr
  maxiters=25
  r_rel_tol=1.0e-8
  r_abs_tol=1.0e-7
  stol=1.0e-16
  solver=superlu
[end]

options

The type = option specifies the name of the nonlinear solver method one wants to use.

maxiters= specifies maximum nonlinear iterations.

r_rel_tol and r_abs_tol represent the relative and absolute errors of the residual(\(||R||\)).

stol= determines tolerance of the displacement error, namely \(||\Delta U||\).

solver= indicates the name of linear solver, it could be: ksp, mumps, and superlu.

supported nonlinear solver method

The full list of the available nonlinear solver method is:

type=nr // for newton-raphson with line search, the default one
type=newtonls // same as the first one
type=newtontr // NR with trust region method
type=bfgs     // BFGS method
type=broyden  // Broyden method