The fields/states to include in the step are defined through the property segvar. The property
segvarspec controls which components of the fields/states in
segvar to include in the step. By default
segvarspec is
all, in which case all components in the fields/states of
segvar are included. By setting
segvarspec to
manual, a subset of the fields/states of
segvar can be included in the step. The components to include in the step are then defined through the property
segcomp.
Analogously, the property subterm controls how each substep is terminated through the properties
maxsubiter,
subiter, and
subntol/
subntolfact for a stationary or time-dependent problem.
The damping technique used in each substep is controlled by the property subdtech. The default setting is
const, which means that damped Newton iterations with a fixed damping factor is used. The damping factor is set in the property
subdamp. The other available damping technique is
autodamp in which case the damping factor is automatically adjusted. For substeps which uses
autodamp, four other properties are supported:
subhnlin,
subinitstep,
subminstep, and
subrstep. For each substep, these properties set the properties
hnlin,
initstep,
minstep, and
rstep supported by the nonlinear solver, see
FullyCoupled.
In substeps with subdtech=const, the property
subjtech controls how often the Jacobian is updated. The values
minimal,
once, and
onevery give the same Jacobian update techniques as they do when applied to the coupled solver through the property
jtech; see
FullyCoupled. The value
onfirst makes the solver update the Jacobian of the substep on the first subiteration each time the substep is solved for. Default value is
onevery for stationary problems and
minimal for time-dependent problems.
When subdtech is set to
ddog (stationary problems), the double dogleg solver is used. The initial damping factor is controlled by the property
subddoginitdamp and the property
subresscale controls the residual scaling. The option
resscale=scalefieldwise scales the equations based on the field-wise sizes of the initial residual. When the option
subresscale=scaleuniform is selected the algorithm terminates on the relative residual based on the initial residual.
The property subtermonres controls the termination criterion for stationary problems when
segterm is not
iter. When
subtermonres=off the estimated error is solution based, with
subtermonres=on it is based on a relative residual, and for
subtermonres=auto the estimated error is the minimum of the solution and residual based errors. For
subtermonres=auto the property
subreserrfact is a scalar factor multiplying the relative residual error. For
subtermonres=both, both methods are used.