SegregatedStep
Handle a segregated solution step, which can be added as a subfeature to a Segregated feature.
Syntax
model.sol(sname).feature(solv).feature(segregated).create(fname,"SegregatedStep")
model.sol(sname).feature(solv).feature(segregated).feature(fname).set(pname,value)
model.sol(sname).feature(solv).feature(segregated).feature(fname).feature(sname).
set(pname,value)
Description
This feature controls one segregated solution step.
Table 6-66: Valid Segregated Step Properties.
Property
Value
Default
Description
linsolver
linear solver tag
 
Linear solver to use.
maxsubiter
integer
20
Maximum number of substep iterations.
segcomp
vector of strings
 
Field/State components in step if segvarspec=manual.
segvar
vector of strings
 
Fields/States in step.
segvarspec
all | manual
all
Include all components or specify which manually.
subaacc
boolean
false
Use Anderson acceleration, when subdtech is set to const or bcktrack.
subaccdelay
nonnegative integer
0
Iteration delay for Anderson acceleration.
subaaccdim
positive integer
10
Dimension of iteration space for Anderson acceleration.
subaaccfact
nonnegative scalar
1
Threshold for Anderson step.
subaaccmix
scalar (0–1)
1
Mixing parameter for Anderson acceleration.
subadapttol
boolean
false
Use adaptive tolerance in the linear solver, when subdtech is set to const or bcktrack.
subadapttolcflweight
boolean
true
Apply CFL weighting for pseudo time stepping and if subadapttol is set to true.
subadapttolerrweight
boolean
true
Apply nonlinear error weighting for models that do not use pseudo time stepping and if subadapttol is set to true.
subatolchoice
fullerrorest | partialerrorest | nonlinresidual | onlycfl | onlyerr
fullerrorest
The error estimation method to use if subadapttol is set to true. fullerrorest uses the full information about the linear and nonlinear error estimates to determine the tolerance. partialerrorest uses partial information about the linear and nonlinear error estimates to determine the tolerance. nonlinresidual uses the nonlinear residual only to determine the tolerance. onlycfl applies CFL suppression to the initial tolerance for models using pseudo time stepping. onlyerr applies a suppression mechanism based on the nonlinear error estimate for models with a stationary solver and not using pseudo time stepping.
subatolthreshold
positive value, 0–1
0.1
The threshold for using the safeguards when determining the tolerance. The higher the value, the faster the safeguards get disabled. Only available when subadapttol is set to true.
subbackdampstep
scalar (0–1)
0.5
Damping in one step, when subdtech is set to bcktrack and subbackmethod is set to conststep.
subbackmethod
fullest | conststep
fullest
Backtracking method when subdtech is set to bcktrack: full estimation or constant step.
subbacktrackonce
boolean
false
Backtrack at least once when subdtech is set to bcktrack and subbackmethod is set to fullest.
subdamp
real
1.0
Substep damping factor.
subdampexponent
real scalar (1–2)
2
Damping exponent, if subatolchoice is set to nonlinresidual.
subdampfactor
real scalar (0–1)
1
Damping factor, if subatolchoice is set to nonlinresidual.
subddoginitdamp
nonnegative scalar
1
Initial damping factor for subdtech set to ddog.
subddogrestart
positive integer
7
Number of iterations before restart for subdtech set to ddog.
subdtech
const | auto | bcktrack | hnlin | ddog
const
Substep damping technique.
subetamax
scalar (0–1)
0.9
Maximal tolerance, if subadapttol is set to true.
subinitstep
real
1
Substep initial damping factor for when subdtech set to auto.
subinitsteph
real
1e-4
Substep initial damping factor when subdtech set to hnlin.
subiter
integer
1
Substep iterations.
subjtech
minimal | once | onfirst | onevery
see below
Substep Jacobian update technique when subdtech is set to const or bcktrack.
submatrixformat
auto | sparse | filled | free
auto
Matrix format: automatic, sparse, filled, or free.
submaxdamp
scalar (0, 1]
1.0
The maximum damping factor. If backtracking returns a damping larger than this value, submaxdamp is used. Available only if subdtech is set to bcktrack.
submindamp
positive scalar
0.1
Substep minimum damping factor when subdtech is set to bcktrack.
subminstep
real
1e-4
Substep minimum damping factor when subdtech is set to auto.
subminsteph
real
1e-8
Substep minimum damping factor when subdtech is set to hnlin.
subntolfact
real
10
Substep tolerance factor.
subrelaxationressmooth
positive scalar
0.2
Relaxation factor, if subressmooth is set to true.
subreserrfact
positive scalar
100
Residual factor when subtermonres is set to auto or both.
subresscale
scalefieldwise | scaleuniform
scalefieldwise
Residual scaling technique for subdtech set to ddog.
subressmooth
boolean
false
Add residual smoothing.
subrstep
real
10
Substep restrictions for step-size update.
subtermconst
iter | tol | itertol
iter
Substep termination technique when subdtech is set to const or bcktrack.
subtermauto
tol | itertol
itertol
Substep termination technique when subdtech is set to auto or hnlin.
subtermonres
off | on | auto | both
auto/off
Termination criterion: Solution, residual, solution or residual, or solution and residual. The default is auto for stationary problems but off for time-dependent problems.
subupdweights
boolean
true
Update automatic scale factors in weights when subdtech is set to const or bcktrack.
subupdweightsauto
true | false | wthresh
true
Updates the weights for automatic scales if they change two orders of magnitude and then restart the Newton solver from the current solution if true. If set to wthresh, you can use thresholds for the weights. All updweights properties are available for stationary and parametric studies and for Newton solvers only (that is, subdtech is not ddog, bcktrack, or const).
subupdweightsdamp
current | manual
current
Available if subupdweightsauto is wthresh. Use fraction of the current damping factor at update (current) or a constant update damping factor (manual).
subupdweightsdampval
positive scalar
1
Fraction of current damping factor. If subupdweightsauto is wthresh and subupdweightsdamp is current.
subupdweightsdampvalconst
positive scalar
0.1
Update damping factor. If subupdweightsauto is wthresh and subupdweightsdamp is manual.
subupdweightsfac
scalar
100
Weights threshold factor for update. If subupdweightsauto is wthresh.
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 or bcktrack, 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.