# 7.8. Solution Control

This section is referenced in the following other sections

- Simulation Setup: Solution Control
- Simulation Setup: Time Step Selection
- Theory: Coupling

## 7.8.1. Solution Control Description

Scope

  Procedure

Summary

  Contains the commands needed to execute an analysis using the arpeggio procedure that uses Solver Control.

    begin Solution Control Description Name

       Use System Name

       begin Adaptiveloop Name
       end

       begin Initialize Name
       end

       begin Parameters For
       end

       begin System Name
       end

    end Solution Control Description Name

### 7.8.1.1. Line Commands

###### Use System

Syntax

  Use System Name

Summary

  This set the name of which system to use.

Parameter | Value | Default
--- | --- | ---
Name | string | –

## 7.8.2. System

Scope

  Solution Control Description

Summary

  This block wraps a solver system for a given name. The NAME parameter is the name used to define the system. There can be more than one system block in the Solver Control Description block. The “use system NAME” line command controls which one is to be used.

    begin System Name

       Adapt Mesh For AdaptRegionName Using AdaptBlockName [When WhenExpression]

       Event Name... [ When When-expression  ]

       Output Name [ When When-expression  ]

       Postprocess Aria Region RegionName ([Equation System EquationSystemName]  | [When WhenExpression])

       Simulation Max Global Iterations {=} Number

       Simulation Start Time {=} Number

       Simulation Termination Time {=} Number

       Transfer Name [ When When-expression  ]

       Use Initialize Name

       begin Adaptiveloop Name
       end

       begin Sequential Name
       end

       begin Transient Name
       end

    end System Name

### 7.8.2.1. Line Commands

###### Adapt Mesh

Syntax

  Adapt Mesh For AdaptRegionName Using AdaptBlockName [When WhenExpression]

Summary

  Adapt the mesh using the adaptive command block name

Parameter | Value | Default
--- | --- | ---
AdaptRegionName | string | –
AdaptBlockName | string | –
WhenExpression | (expression) | –

###### Event

Syntax

  Event Name… [ When When-expression ]

Summary

  Used within a Solver Control block to indicate a single step that has no time associated with it. It can cause a solution transfer between regions or cause something to print.

Parameter | Value | Default
--- | --- | ---
Name | string… | –

###### Output

Syntax

  Output Name [ When When-expression ]

Summary

  A Solver Control Output line command which execute a perform I/O on the region.

Parameter | Value | Default
--- | --- | ---
Name | string | –

###### Postprocess Aria Region

Syntax

  Postprocess Aria Region RegionName ([Equation System EquationSystemName] | [When WhenExpression])

Summary

  Run Aria Region postprocessors. If specified, only the single equation system’s PPs are run.

Parameter | Value | Default
--- | --- | ---
RegionName | string | –
EquationSystemName | string | –
WhenExpression | (expression) | –

###### Simulation Max Global Iterations

Syntax

  Simulation Max Global Iterations {=} Number

Summary

  The Total number of Solves.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Number | integer | –

###### Simulation Start Time

Syntax

  Simulation Start Time {=} Number

Summary

  Simulation starting time. (by default 0.0)

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Number | real | –

###### Simulation Termination Time

Syntax

  Simulation Termination Time {=} Number

Summary

  The drop dead time.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Number | real | –

###### Transfer

Syntax

  Transfer Name [ When When-expression ]

Summary

  A Solver Control Transfer line command which executes all transfers defined from the specified region. All transfers with a send region of ‘name’ will be executed.

Parameter | Value | Default
--- | --- | ---
Name | string | –

###### Use Initialize

Syntax

  Use Initialize Name

Summary

  This set the name of which initialization to use.

Parameter | Value | Default
--- | --- | ---
Name | string | –

## 7.8.3. Transient

Scope

  Adaptiveloop, System

Summary

  This block is used to wrap a time loop.

    begin Transient Name

       Advance Name... [ When When-expression  ]

       Adapt Mesh For AdaptRegionName Using AdaptBlockName [When WhenExpression]

       Event Name... [ When When-expression  ]

       Involve Name

       Output Name [ When When-expression  ]

       Postprocess Aria Region RegionName ([Equation System EquationSystemName]  | [When WhenExpression])

       Transfer Name [ When When-expression  ]

       begin Adaptiveloop Name
       end

       begin Nonlinear Name
       end

       begin Subcycle Name
       end

    end Transient Name

### 7.8.3.1. Line Commands

###### Advance

Syntax

  Advance Name… [ When When-expression ]

Summary

  Used within a Solver Control block to indicate a single step that advances the solution. The name is that matches the physics.

Parameter | Value | Default
--- | --- | ---
Name | string… | –

###### Adapt Mesh

Syntax

  Adapt Mesh For AdaptRegionName Using AdaptBlockName [When WhenExpression]

Summary

  Adapt the mesh using the adaptive command block name

Parameter | Value | Default
--- | --- | ---
AdaptRegionName | string | –
AdaptBlockName | string | –
WhenExpression | (expression) | –

###### Event

Syntax

  Event Name… [ When When-expression ]

Summary

  Used within a Solver Control block to indicate a single step that has no time associated with it. It can cause a solution transfer between regions or cause something to print.

Parameter | Value | Default
--- | --- | ---
Name | string… | –

###### Involve

Syntax

  Involve Name

Summary

  Specify a physics participant to a coupled problem solved using matrix-free nonlinear.

Parameter | Value | Default
--- | --- | ---
Name | string | –

###### Output

Syntax

  Output Name [ When When-expression ]

Summary

  A Solver Control Output line command which execute a perform I/O on the region.

Parameter | Value | Default
--- | --- | ---
Name | string | –

###### Postprocess Aria Region

Syntax

  Postprocess Aria Region RegionName ([Equation System EquationSystemName] | [When WhenExpression])

Summary

  Run Aria Region postprocessors. If specified, only the single equation system’s PPs are run.

Parameter | Value | Default
--- | --- | ---
RegionName | string | –
EquationSystemName | string | –
WhenExpression | (expression) | –

###### Transfer

Syntax

  Transfer Name [ When When-expression ]

Summary

  A Solver Control Transfer line command which executes all transfers defined from the specified region. All transfers with a send region of ‘name’ will be executed.

Parameter | Value | Default
--- | --- | ---
Name | string | –

## 7.8.4. Nonlinear

Scope

  Sequential, Transient

Summary

  This block is used to wrap a nonlinear solve loop.

    begin Nonlinear Name

       Advance Name... [ When When-expression  ]

       Adapt Mesh For AdaptRegionName Using AdaptBlockName [When WhenExpression]

       Event Name... [ When When-expression  ]

       Involve Name

       Output Name [ When When-expression  ]

       Postprocess Aria Region RegionName ([Equation System EquationSystemName]  | [When WhenExpression])

       Transfer Name [ When When-expression  ]

       begin Subcycle Name
       end

    end Nonlinear Name

### 7.8.4.1. Line Commands

###### Advance

Syntax

  Advance Name… [ When When-expression ]

Summary

  Used within a Solver Control block to indicate a single step that advances the solution. The name is that matches the physics.

Parameter | Value | Default
--- | --- | ---
Name | string… | –

###### Adapt Mesh

Syntax

  Adapt Mesh For AdaptRegionName Using AdaptBlockName [When WhenExpression]

Summary

  Adapt the mesh using the adaptive command block name

Parameter | Value | Default
--- | --- | ---
AdaptRegionName | string | –
AdaptBlockName | string | –
WhenExpression | (expression) | –

###### Event

Syntax

  Event Name… [ When When-expression ]

Summary

  Used within a Solver Control block to indicate a single step that has no time associated with it. It can cause a solution transfer between regions or cause something to print.

Parameter | Value | Default
--- | --- | ---
Name | string… | –

###### Involve

Syntax

  Involve Name

Summary

  Specify a physics participant to a coupled problem solved using matrix-free nonlinear.

Parameter | Value | Default
--- | --- | ---
Name | string | –

###### Output

Syntax

  Output Name [ When When-expression ]

Summary

  A Solver Control Output line command which execute a perform I/O on the region.

Parameter | Value | Default
--- | --- | ---
Name | string | –

###### Postprocess Aria Region

Syntax

  Postprocess Aria Region RegionName ([Equation System EquationSystemName] | [When WhenExpression])

Summary

  Run Aria Region postprocessors. If specified, only the single equation system’s PPs are run.

Parameter | Value | Default
--- | --- | ---
RegionName | string | –
EquationSystemName | string | –
WhenExpression | (expression) | –

###### Transfer

Syntax

  Transfer Name [ When When-expression ]

Summary

  A Solver Control Transfer line command which executes all transfers defined from the specified region. All transfers with a send region of ‘name’ will be executed.

Parameter | Value | Default
--- | --- | ---
Name | string | –

## 7.8.5. Subcycle

Scope

  Nonlinear, Transient

Summary

  This block is used to wrap a subcycle time loop.

    begin Subcycle Name

       Advance Name... [ When When-expression  ]

       Adapt Mesh For AdaptRegionName Using AdaptBlockName [When WhenExpression]

       Event Name... [ When When-expression  ]

       Involve Name

       Output Name [ When When-expression  ]

       Postprocess Aria Region RegionName ([Equation System EquationSystemName]  | [When WhenExpression])

       Transfer Name [ When When-expression  ]

    end Subcycle Name

### 7.8.5.1. Line Commands

###### Advance

Syntax

  Advance Name… [ When When-expression ]

Summary

  Used within a Solver Control block to indicate a single step that advances the solution. The name is that matches the physics.

Parameter | Value | Default
--- | --- | ---
Name | string… | –

###### Adapt Mesh

Syntax

  Adapt Mesh For AdaptRegionName Using AdaptBlockName [When WhenExpression]

Summary

  Adapt the mesh using the adaptive command block name

Parameter | Value | Default
--- | --- | ---
AdaptRegionName | string | –
AdaptBlockName | string | –
WhenExpression | (expression) | –

###### Event

Syntax

  Event Name… [ When When-expression ]

Summary

  Used within a Solver Control block to indicate a single step that has no time associated with it. It can cause a solution transfer between regions or cause something to print.

Parameter | Value | Default
--- | --- | ---
Name | string… | –

###### Involve

Syntax

  Involve Name

Summary

  Specify a physics participant to a coupled problem solved using matrix-free nonlinear.

Parameter | Value | Default
--- | --- | ---
Name | string | –

###### Output

Syntax

  Output Name [ When When-expression ]

Summary

  A Solver Control Output line command which execute a perform I/O on the region.

Parameter | Value | Default
--- | --- | ---
Name | string | –

###### Postprocess Aria Region

Syntax

  Postprocess Aria Region RegionName ([Equation System EquationSystemName] | [When WhenExpression])

Summary

  Run Aria Region postprocessors. If specified, only the single equation system’s PPs are run.

Parameter | Value | Default
--- | --- | ---
RegionName | string | –
EquationSystemName | string | –
WhenExpression | (expression) | –

###### Transfer

Syntax

  Transfer Name [ When When-expression ]

Summary

  A Solver Control Transfer line command which executes all transfers defined from the specified region. All transfers with a send region of ‘name’ will be executed.

Parameter | Value | Default
--- | --- | ---
Name | string | –

## 7.8.6. Sequential

Scope

  Adaptiveloop, System

Summary

  This block is used to wrap a sequential solution. It is used to wrap a sequence of Non-Linear or pseudo time solve step solves.

    begin Sequential Name

       Advance Name... [ When When-expression  ]

       Adapt Mesh For AdaptRegionName Using AdaptBlockName [When WhenExpression]

       Event Name... [ When When-expression  ]

       Involve Name

       Output Name [ When When-expression  ]

       Postprocess Aria Region RegionName ([Equation System EquationSystemName]  | [When WhenExpression])

       Transfer Name [ When When-expression  ]

       begin Adaptiveloop Name
       end

       begin Nonlinear Name
       end

    end Sequential Name

### 7.8.6.1. Line Commands

###### Advance

Syntax

  Advance Name… [ When When-expression ]

Summary

  Used within a Solver Control block to indicate a single step that advances the solution. The name is that matches the physics.

Parameter | Value | Default
--- | --- | ---
Name | string… | –

###### Adapt Mesh

Syntax

  Adapt Mesh For AdaptRegionName Using AdaptBlockName [When WhenExpression]

Summary

  Adapt the mesh using the adaptive command block name

Parameter | Value | Default
--- | --- | ---
AdaptRegionName | string | –
AdaptBlockName | string | –
WhenExpression | (expression) | –

###### Event

Syntax

  Event Name… [ When When-expression ]

Summary

  Used within a Solver Control block to indicate a single step that has no time associated with it. It can cause a solution transfer between regions or cause something to print.

Parameter | Value | Default
--- | --- | ---
Name | string… | –

###### Involve

Syntax

  Involve Name

Summary

  Specify a physics participant to a coupled problem solved using matrix-free nonlinear.

Parameter | Value | Default
--- | --- | ---
Name | string | –

###### Output

Syntax

  Output Name [ When When-expression ]

Summary

  A Solver Control Output line command which execute a perform I/O on the region.

Parameter | Value | Default
--- | --- | ---
Name | string | –

###### Postprocess Aria Region

Syntax

  Postprocess Aria Region RegionName ([Equation System EquationSystemName] | [When WhenExpression])

Summary

  Run Aria Region postprocessors. If specified, only the single equation system’s PPs are run.

Parameter | Value | Default
--- | --- | ---
RegionName | string | –
EquationSystemName | string | –
WhenExpression | (expression) | –

###### Transfer

Syntax

  Transfer Name [ When When-expression ]

Summary

  A Solver Control Transfer line command which executes all transfers defined from the specified region. All transfers with a send region of ‘name’ will be executed.

Parameter | Value | Default
--- | --- | ---
Name | string | –

## 7.8.7. Initialize

Scope

  Solution Control Description

Summary

  This block wraps a initializer for a given name. The NAME parameter is the name used to define the initialization block. There can be more than one initialize block in the Solver Control Description block. The “use initialize NAME” line command controls which one is to be used.

    begin Initialize Name

       Advance Name... [ When When-expression  ]

       Event Name... [ When When-expression  ]

       Involve Name

       Transfer Name [ When When-expression  ]

    end Initialize Name

### 7.8.7.1. Line Commands

###### Advance

Syntax

  Advance Name… [ When When-expression ]

Summary

  Used within a Solver Control block to indicate a single step that advances the solution. The name is that matches the physics.

Parameter | Value | Default
--- | --- | ---
Name | string… | –

###### Event

Syntax

  Event Name… [ When When-expression ]

Summary

  Used within a Solver Control block to indicate a single step that has no time associated with it. It can cause a solution transfer between regions or cause something to print.

Parameter | Value | Default
--- | --- | ---
Name | string… | –

###### Involve

Syntax

  Involve Name

Summary

  Specify a physics participant to a coupled problem solved using matrix-free nonlinear.

Parameter | Value | Default
--- | --- | ---
Name | string | –

###### Transfer

Syntax

  Transfer Name [ When When-expression ]

Summary

  A Solver Control Transfer line command which executes all transfers defined from the specified region. All transfers with a send region of ‘name’ will be executed.

Parameter | Value | Default
--- | --- | ---
Name | string | –

## 7.8.8. Parameters For

Scope

  Solution Control Description

Summary

  A Solver Control PARAMETERS block to set up control data for the SC_type parameter. Inside this block one sets the time step parameters or nonlinear parameters.

    begin Parameters For

       Converged When Convergence-expression

       Incremental Number Of Steps {=} Number

       Initial Deltat {=} Number

       Number Of Adaptivity Steps {=} Number

       Number Of Steps {=} Number

       Reinitialize Transient

       Start Time {=} Number

       Suppress Output From Nonlinear Loop

       Termination Time {=} Number

       Time Step Quantum {=} TimeStepQuantum

       Time Step Style TimeStepStyle...

       Total Change In Time {=} Number

       begin Parameters For Aria Region RegionName
       end

    end Parameters For

### 7.8.8.1. Line Commands

###### Converged When

Syntax

  Converged When Convergence-expression

Summary

  Set the convergence expression.

Parameter | Value | Default
--- | --- | ---
Convergence-expression | (expression) | –

###### Incremental Number Of Steps

Syntax

  Incremental Number Of Steps {=} Number

Summary

  The incremental number steps to run the time for nonlinear loop. Number of time steps to run after restarting. NUMBER OF STEPS is total number of steps to run

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Number | integer | –

###### Initial Deltat

Syntax

  Initial Deltat {=} Number

Summary

  Assign an initial delta T

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Number | real | –

###### Number Of Adaptivity Steps

Syntax

  Number Of Adaptivity Steps {=} Number

Summary

  The number steps to run the time or nonlinear loop

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Number | integer | –

###### Number Of Steps

Syntax

  Number Of Steps {=} Number

Summary

  The number steps to run the time for nonlinear loop

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Number | integer | –

###### Reinitialize Transient

Syntax

  Reinitialize Transient

Summary

  Reset time and re-initialize regions each step of the adaptivity loop.

###### Start Time

Syntax

  Start Time {=} Number

Summary

  Assign a start time.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Number | real | –

###### Suppress Output From Nonlinear Loop

Syntax

  Suppress Output From Nonlinear Loop

Summary

  Specify that the nonlinear loop will not output. Output will be handled by calls outside of the nonlinear loop (such as an additional advance region call).

###### Termination Time

Syntax

  Termination Time {=} Number

Summary

  Assign a final time to stop

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Number | real | –

###### Time Step Quantum

Syntax

  Time Step Quantum {=} TimeStepQuantum

Summary

  Set the time stepping quantum time for SNAP style stepping.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
TimeStepQuantum | real | –

###### Time Step Style

Syntax

  Time Step Style TimeStepStyle…

Summary

  Set the time stepping style.

  When CLIP is specified, the time step size will be clipped at the last step of the transient loop so that it ends at the transient loop’s end time. If clip is not specified, the last time is allowed to exceed to the transient loop’s end time and the following transient loop will start at the exceeded end time.

  When SNAP is specified, the time step is broken down into “quantum” time units. By default this quantum time is 12 orders of magnitude down from the difference between the start and end time for the transient loop. This value can be overridden using the TIME STEP QUANTUM line command. All time values are “snapped” to multiples of the quantum time by rounding to the nearest quantum multiple.

Parameter | Value | Default
--- | --- | ---
TimeStepStyle | {clip | noclip | nosnap | snap} | CLIP NOSNAP

###### Total Change In Time

Syntax

  Total Change In Time {=} Number

Summary

  Use this number and the initial time to compute termination time.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Number | real | –

## 7.8.9. Parameters For Aria Region

Scope

  Parameters For

Summary

  Defines region specific time stepping data

    begin Parameters For Aria Region RegionName

       Allow Order Switch For HowMany Steps

       Courant Limit {=} Courant_limit

       Fail Time Step On Bad Aztec Solver Status

       Fail Time Step When Time Step Size Ratio Is Below Ratio

       Failed Time Step Size Ratio {=} Ratio

       Initial Nonlinear Residual Tolerance For Time Step Control {=} tolerance

       Initial Time Step Size {=} Dt

       Interface Courant Limit {=} Interface Courant_limit

       Known Time Discontinuities {=} times...

       Limit Solution Increment Field_name {=} Value [ Action  ]

       Maximum Acceptable Linear Residual Ratio {=} Ratio

       Maximum Consecutive Time Step Failures {=} NumFails

       Maximum Global Var Limit Encore_name {=} Value [ Action  ]

       Maximum Linear Residual Ratio {=} Ratio

       Maximum Solution Limit Field_name {=} Value [ Action  ]

       Maximum Time Step Size {=} Dt

       Maximum Time Step Size Ratio {=} Ratio

       Mesh Courant Limit {=} Mesh Courant_limit

       Minimum Global Var Limit Encore_name {=} Value [ Action  ]

       Minimum Resolved Time Step Size {=} Dt

       Minimum Solution Limit Field_name {=} Value [ Action  ]

       Minimum Time Step Size {=} Dt

       Predictor Order {=} order

       Predictor-Corrector Begin After Step {=} Step

       Predictor-Corrector Field Normalization {on} Field_name {=} {courant | max | mesh | none | user} [ Scaling  ]

       Predictor-Corrector Normalization {=} {courant | max | mesh | none | user} [ Scaling  ]

       Predictor-Corrector Tolerance {=} Predictor_corrector_tolerance

       Reset Initial Time Step Size

       Slope Of Time Step Size {=} slope

       Stop When Initial Nonlinear Residual Is Below Tol

       Time Integration Method {=} {average_acceleration | backward_euler | bdf2 | first_order | midpoint_rule | second_order}

       Time Step Variation {=} {adaptive | fixed}

       Use Initial Nonlinear Residual For Time Step Control {=} {false | no | off | on | true | yes}

    end Parameters For Aria Region RegionName

### 7.8.9.1. Line Commands

###### Allow Order Switch For

Syntax

  Allow Order Switch For HowMany Steps

Summary

  Allow the switching of time integration order from a higher order to first order.

Description

  This command allows for the switching of a higher order method to a first order method for a specified number of steps in order to improve the robustness of the simulation especially in the region of discontinuities such as chemistry shutoff. This command is mostly useful in the context of a SECOND_ORDER time integration method.

Parameter | Value | Default
--- | --- | ---
HowMany | integer | –

###### Courant Limit

Syntax

  Courant Limit {=} Courant_limit

Summary

  The Courant Number limit. A value of 0.0 denotes INACTIVE.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Courant_limit | real | 0.0

###### Fail Time Step On Bad Aztec Solver Status

Syntax

  Fail Time Step On Bad Aztec Solver Status

Summary

  This command is deprecated and no longer has any effect.

###### Fail Time Step When Time Step Size Ratio Is Below

Syntax

  Fail Time Step When Time Step Size Ratio Is Below Ratio

Summary

  Specify lower bound for adaptive time step size ratio failure criteria.

  If the adaptive time step size ratio falls below this value, Aria will fail the time step. This criteria is specified in terms of the size of the time step size ratio, defined as . When the adaptive time stepper senses the time step being cut back too much, the time step fails. The default is equal to the FAILED TIME STEP SIZE RATIO.

  In simulations where the predicted time step is reduced substantially, a time step may fail repeatedly on this criterion. In that event the user may want to set this Ratio to a small positive value, possibly even zero.

Parameter | Value | Default
--- | --- | ---
Ratio | real | –

###### Failed Time Step Size Ratio

Syntax

  Failed Time Step Size Ratio {=} Ratio

Summary

  Specifies the factor used to cut the time step size when a step fails.

  When a time step fails, the time step size is reduced by this factor.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Ratio | real | 0.5

###### Initial Nonlinear Residual Tolerance For Time Step Control

Syntax

  Initial Nonlinear Residual Tolerance For Time Step Control {=} tolerance

Summary

  Set initial nonlinear residual tolerance for time step control.

Description

  Sets the tolerance on the initial nonlinear residual to be used for time step control.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
tolerance | real | 1.0

###### Initial Time Step Size

Syntax

  Initial Time Step Size {=} Dt

Summary

  Specifies the initial time step size for the given parameter block.

  The initial time step size should always be specified for FIXED time stepping and for the starting time block of ADAPTIVE time stepping. When no other command lines affecting timestep are provided in the time step parameter block the time step will remain constant over the time extent of the parameter block.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Dt | real | –

###### Interface Courant Limit

Syntax

  Interface Courant Limit {=} Interface Courant_limit

Summary

  The Interface Courant Number limit. Applies to both diffuse level set and CDFEM problems. A value of 0.0 denotes INACTIVE.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Interface Courant_limit | real | 0.0

###### Known Time Discontinuities

Syntax

  Known Time Discontinuities {=} times…

Summary

  Specifies known time discontinuities in the solution that the adaptive time stepping procedure must capture.

Description

  Allows user to specify certain times that the adaptive time stepper must solve at because the solution is known to have a discontinuity there. This is useful for problems where the boundary conditions change suddenly for example.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
times | real… | –

###### Limit Solution Increment

Syntax

  Limit Solution Increment Field_name {=} Value [ Action ]

Summary

  Provides user control for limiting maximum change in a chosen solution Field over a timestep. When action is PREDICT a time step estimation is computed based upon the predicted solution change. When action is FAIL_STEP the time step is still predicted but the the time step will also fail if the suggested solution increment is exceeded.

Description

  This command allows one to roughly specify the maximum magnitude that a solution Field can change within a step. A solution increment is estimated based upon the maximum change in the Field in the previous timestep and the proposed adaptive timestep. When the specified value of maximum solution increment is exceeded, the proposed adaptive timestep is reduced in an attempt to limit the solution increment.

  One command line should be supplied for each solution Field one wishes to restrict. The restriction is applied directly to the solution Field values, no scaling is invoked.

Parameter | Value | Default
--- | --- | ---
Field_name | string | –
{=} | {= | are | is} | –
Value | real | REAL_MAX

###### Maximum Acceptable Linear Residual Ratio

Syntax

  Maximum Acceptable Linear Residual Ratio {=} Ratio

Summary

  Specifies a failure criterion for a nonlinear step based on the ratio of the final linear residual to a nonlinear residual.

  The ratio must be greater than zero and less than one.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Ratio | real | –

###### Maximum Consecutive Time Step Failures

Syntax

  Maximum Consecutive Time Step Failures {=} NumFails

Summary

  Specifies a maximum consecutive of time step failures before a simulation is terminated. This prevents the application from continued cutback of the time step when recovery of the solution is unlikely.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
NumFails | integer | 20

###### Maximum Global Var Limit

Syntax

  Maximum Global Var Limit Encore_name {=} Value [ Action ]

Summary

  This command allows the simulation to continue only when the given Encore variable is lower than a certain magnitude. Inclusion of the optional argument RETRY will cause the solution step to fail and the time step to be reduced. This sequence will be carried out a maximum of three steps, after which the simulation will be terminated.

Description

  This command allows the simulation to continue only when the given Encore variable is lower than a certain magnitude.

Parameter | Value | Default
--- | --- | ---
Encore_name | string | –
{=} | {= | are | is} | –
Value | real | –

###### Maximum Linear Residual Ratio

Syntax

  Maximum Linear Residual Ratio {=} Ratio

Summary

  Specifies a failure criterion for a nonlinear step based on the ratio of a nonlinear residual to the initial nonlinear residual.

  NOTE: The linear residual is not utilized with this check.

  This criteria is not be used unless requested by the user.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Ratio | real | –

###### Maximum Solution Limit

Syntax

  Maximum Solution Limit Field_name {=} Value [ Action ]

Summary

  Provides user control for limiting maximum value of a Field solution over a time step. Optional parameters are continue or terminate. When a step fails the step will be cut back and and the optional behavior is invoked when three consecutive fails have occurred. Default behavior is to terminate.

Description

  This command allows one to restrict the maximum magnitude that a solution Field can achieve within a simulation by causing the time step to fail when the Field value exceeds a user specified magnitude.

  Oftentimes the maximum value will be tied to an event that occurs at a particular magnitude of the Field. This command can be used to impose a different solution behavior when this magnitude of the Field is realized by forcing a failure of the solution step. When the step is failed due to solution limit then cutback of the time step is allowed to occur for two consecutive steps. If the time step is cut back a third time in succession, the specified action of the command will be invoked.

  By default the simulation will terminate when the maximum value is reached. If the optional argument is “continue” then time step failure will be over-ridden and the solution sequence will continue, presumably evolving toward lower magnitude values of the Field. This behavior may enable one to overcome large reductions in time step at discontinuous events which may occur for maximum values of the Field.

Parameter | Value | Default
--- | --- | ---
Field_name | string | –
{=} | {= | are | is} | –
Value | real | REAL_MAX

###### Maximum Time Step Size

Syntax

  Maximum Time Step Size {=} Dt

Summary

  Specifies the maximum time step size for this parameter block.

  The time step will not be allowed to exceed this value, regardless of adaptive time step selection and regardless of time step requests for other regions (for loosely coupled simulations).

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Dt | real | REAL_MAX

###### Maximum Time Step Size Ratio

Syntax

  Maximum Time Step Size Ratio {=} Ratio

Summary

  Specifies the maximum allowable growth rate of the adaptive time step size.

  If the time step selection computes a new time step size that exceeds the previous step size by more than this amount, then the new step size is limited to the product of this factor and the previous step size.

  The default is 2.0 for FIRST_ORDER and SECOND_ORDER integration methods.

  For BDF2 a value of 2.4 is imposed to enforce stability of the integrator.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Ratio | real | 2.0/2.4

###### Mesh Courant Limit

Syntax

  Mesh Courant Limit {=} Mesh Courant_limit

Summary

  The Mesh Courant Number limit. Applies to problems with mesh motion. CFL condition is applied based on normal mesh velocities at the boundary with the length scale taken as the element volume divided by the element surface area. A value of 0.0 denotes INACTIVE.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Mesh Courant_limit | real | 0.0

###### Minimum Global Var Limit

Syntax

  Minimum Global Var Limit Encore_name {=} Value [ Action ]

Summary

  This command allows the simulation to continue only when the given Encore variable is higher than a certain magnitude. Inclusion of the optional argument, RETRY, will cause the solution step to fail and the time step to be reduced. This sequence will be carried out a maximum of three steps, after which the simulation will be terminated.

Description

  This command allows the simulation to continue only when the given Encore variable is higher than a certain magnitude.

Parameter | Value | Default
--- | --- | ---
Encore_name | string | –
{=} | {= | are | is} | –
Value | real | –

###### Minimum Resolved Time Step Size

Syntax

  Minimum Resolved Time Step Size {=} Dt

Summary

  Specifies the minimum resolved time step size. If the time step size lies below this value, the step will not fail when the time step size ratio falls too low.

  This setting serves as a floor value since the adaptive time stepper will not select a time step size below this value, and any predictor-corrector errors are neglected when the time step size falls below this value.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Dt | real | 0.0

###### Minimum Solution Limit

Syntax

  Minimum Solution Limit Field_name {=} Value [ Action ]

Summary

  Provides user control for limiting minimum value of a Field solution over a time step. Optional parameters are continue or terminate. When a step fails the step will be cut back and and the optional behavior is invoked when three consecutive fails have occurred. Default behavior is to terminate.

Description

  By default the solution minimum limit for all Fields is not active. This command allows one to restrict the minimum magnitude that a solution Field can achieve within a simulation by causing the time step to fail when the Field value goes below a user specified value

  See MAXIMUM SOLUTION LIMIT command for more info.

Parameter | Value | Default
--- | --- | ---
Field_name | string | –
{=} | {= | are | is} | –
Value | real | –

###### Minimum Time Step Size

Syntax

  Minimum Time Step Size {=} Dt

Summary

  Specifies the minimum time step size for the given parameter block. The time step will not be allowed to fall below this value, regardless of adaptive time step selection and regardless of time step requests from other regions (for loosely coupled simulations).

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Dt | real | 1.0e-16

###### Predictor Order

Syntax

  Predictor Order {=} order

Summary

  Specifies the order of the extrapolation used to predict the solution in transient simulations. An order of 0 corresponds to no extrapolation, instead copying the previous solution into the predicted solution.

Description

  This command sets the order of extrapolation in the predictor for transient problems. A value of 0 basically turns off the extrapolation, and instead copies to old solution to the predicted solution.

  The`PREDICTOR ORDER` defaults to 0 for problems if Gas Dynamics equations are defined. Otherwise, it is set to the order of the time integrator for the current time block i.e 1 for first order and 2 for second order

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
order | integer | –

###### Predictor-Corrector Begin After Step

Syntax

  Predictor-Corrector Begin After Step {=} Step

Summary

  Specifies after which solution step the Predictor-Corrector timestep calculation will begin to be used in computing an adaptive timestep. Predictor error will always be computed but will not actually be used until the prescribed step is reached.

  Default value is 2 for first-order time integration and 3 for second-order time integration. Thus for first-order time integration, a candidate predictor-corrector timestep could appear in step 3.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Step | integer | 2 / 3

###### Predictor-Corrector Field Normalization

Syntax

  Predictor-Corrector Field Normalization {on} Field_name {=} {courant | max | mesh | none | user} [ Scaling ]

Summary

  Allows user to change the predictor-corrector normalization type for a given field variable separately from the global option.

Description

  Allows user to change the predictor-corrector normalization type for a given field variable separately from the global option.

  Normalization types are:

  - NONE: Scale by unity

  - MAX (default): Scale by the maximum field value

  - USER: Scale by a constant (user-supplied) value

Parameter | Value | Default
--- | --- | ---
{on} | {@ | at | for | in | on | over} | –
Field_name | string | –
{=} | {= | are | is} | –
Norm_type | {courant | max | mesh | none | user} | MAX

###### Predictor-Corrector Normalization

Syntax

  Predictor-Corrector Normalization {=} {courant | max | mesh | none | user} [ Scaling ]

Summary

  Provides the ability to specify how the predictor-corrector error is normalized.

  Currently supported values are MAX, NONE, and USER. If desired, L2 could be added easily. A possibly better method would be to allow user-specified scales for the variables but that’s not yet supported.

  The reason for allowing NONE (or even better, a user-specified scale) is to better handle problems that involve something that is zero-based with finite changes. This can happen in ALE problems where the adaptive time stepper is overly restrictive initially when the displacements are all nearly zero, but growing to some finite value.

  Default is MAX.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Normalization | {courant | max | mesh | none | user} | MAX

###### Predictor-Corrector Tolerance

Syntax

  Predictor-Corrector Tolerance {=} Predictor_corrector_tolerance

Summary

  Specifies the tolerance for the difference between the predicted solution and the implicitly solved corrector solution used in adaptive time step selection.

  The adaptive time step selection formula is

  where is the time step size from the most recent solution, is the new time step size, is the predictor-corrector tolerance and is the norm of the difference between the predicted and actual solutions at time . For first order time integration and . For second order time integration and . See [57].

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Predictor_corrector_tolerance | real | 0.001

###### Reset Initial Time Step Size

Syntax

  Reset Initial Time Step Size

Summary

  Enforce use of initial time step size specification.

Description

  When using adaptive time stepping with restart the initial time step size is taken from the restart file rather than the INITIAL TIME STEP SIZE specification. This choice of time step can be problematic if one wishes to change model features at the beginning of a restart. This command forces the time step selection to respect an initial time step size specification.

###### Slope Of Time Step Size

Syntax

  Slope Of Time Step Size {=} slope

Summary

  Specifies the linear growth rate of the time step size for the given parameter block. The time step size will grow by this amount at each step unless limited by other factors.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
slope | real | –

###### Stop When Initial Nonlinear Residual Is Below

Syntax

  Stop When Initial Nonlinear Residual Is Below Tol

Summary

  Specify time block termination criteria based upon nonlinear residual value. If the initial nonlinear residual falls below this value, Aria will end the time block. This is useful for obtaining pseudo-transient solutions of steady-state problems.

Parameter | Value | Default
--- | --- | ---
Tol | real | –

###### Time Integration Method

Syntax

  Time Integration Method {=} {average_acceleration | backward_euler | bdf2 | first_order | midpoint_rule | second_order}

Summary

  Specifies the order of time integration.

  Valid options are BACKWARD_EULER, FIRST_ORDER, SECOND_ORDER, BDF2, MIDPOINT_RULE and AVERAGE_ACCELERATION.

  Note that the stability criteria of BDF2 will restrict the timestep growth by imposing a MAXIMUM TIME STEP SIZE RATIO of 2.14.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Time_integration_method | {average_acceleration | backward_euler | bdf2 | first_order | midpoint_rule | second_order} | –

###### Time Step Variation

Syntax

  Time Step Variation {=} {adaptive | fixed}

Summary

  Specifies how the time step sizes are to be derived. Choose between FIXED and ADAPTIVE time step selection methods.

  When the time step is ADAPTIVE the time step is determined using a predictor-corrector error criteria.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Time_step_variation | {adaptive | fixed} | –

###### Use Initial Nonlinear Residual For Time Step Control

Syntax

  Use Initial Nonlinear Residual For Time Step Control {=} {false | no | off | on | true | yes}

Summary

  Enable use of initial nonlinear residual as an error estimate to control timestep for loosely coupled problems.

Description

  When enabled this option will treat the initial non-linear residual as a proxy for the error in region-region convergence for loosely coupled problems. The time step will be controlled using a predictor-corrector like algorithm.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
enable | {false | no | off | on | true | yes} | –