# 6.5. Time Control

This section is referenced in the following other sections

- Simulation Setup: Time Control

## 6.5.1. Time Control

Scope

  Fuego Procedure

Summary

  Defines the time control for the problem in the procedure scope.

Description

  This describes the Time Control block which is convenient for single-physics applications. The Solution Control block is described elsewhere, and is appropriate for multiphysics applications.

    begin Time Control

       Termination Time {=} Tend

       begin Time Stepping Block BlockName
       end

    end Time Control

### 6.5.1.1. Line Commands

###### Termination Time

Syntax

  Termination Time {=} Tend

Summary

  Specifies the ending time for this solution period.

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

## 6.5.2. Time Stepping Block

Scope

  Time Control

Summary

  Defines the time and time step parameters for a solution period.

    begin Time Stepping Block BlockName

       Number Of Time Steps {=} Nsteps

       Start Time {=} Tstart

       Time Step {=} Dt0

       begin Parameters For Fuego Region RegionName
       end

    end Time Stepping Block BlockName

### 6.5.2.1. Line Commands

###### Number Of Time Steps

Syntax

  Number Of Time Steps {=} Nsteps

Summary

  Specifies the number of time steps in this solution period.

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

###### Start Time

Syntax

  Start Time {=} Tstart

Summary

  Specifies the starting time for this solution period.

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

###### Time Step

Syntax

  Time Step {=} Dt0

Summary

  Specifies the time step size for this solution period.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Dt0 | real | –

## 6.5.3. Parameters For Fuego Region

Scope

  Parameters For

Summary

  Defines region-specific time stepping data.

    begin Parameters For Fuego Region RegionName

       Cfl Limit {=} Clfmax

       Iteration At Skip Step {=} SkipIter

       Maximum Time Step {=} DtMax

       Minimum Time Step {=} DtMin

       Skip Step {=} SkipStep

       Skip Steps For Pmr {=} PMRSkip

       Time Step Change Factor {=} Change

       Transient Step Type {=} {automatic | fixed | invalid time step type}

    end Parameters For Fuego Region RegionName

### 6.5.3.1. Line Commands

###### Cfl Limit

Syntax

  Cfl Limit {=} Clfmax

Summary

  Specifies the maximum value of the CFL number that is used to determine the auto time step.

Description

  Need a fuller description here.

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

###### Iteration At Skip Step

Syntax

  Iteration At Skip Step {=} SkipIter

Summary

  Controls the number of iterations in between a skip step.

Description

  This is the first implementation of the ability to freeze the Fuego region and allow time advancement without a Fluids/Conduction solve. In the near future, solution control will allow this feature in a more elegant manner.

  For now, the iteration count will allow for a given number of iterations when the Afgo regions solve is “active”, that is not during a skip step.

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

###### Maximum Time Step

Syntax

  Maximum Time Step {=} DtMax

Summary

  Specifies the maximum allowable time increment for auto timestepping.

Description

  Need a fuller description here.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
DtMax | real | 1.0e12

###### Minimum Time Step

Syntax

  Minimum Time Step {=} DtMin

Summary

  Specifies the minimum allowable time increment for auto timestepping.

Description

  Need a fuller description here.

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

###### Skip Step

Syntax

  Skip Step {=} SkipStep

Summary

  Controls the frequency of Fuego (Afgo) iteration.

Description

  This is the first implementation of the ability to freeze the Fuego region and allow time advancement without a Fluids/Conduction solve. In the near future, solution control will allow this feature in a more elegant manner.

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

###### Skip Steps For Pmr

Syntax

  Skip Steps For Pmr {=} PMRSkip

Summary

  Controls the frequency of PMR solve.

Description

  Set the PMR solve interval. Default is 1 (every step).

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
PMRSkip | integer | 1

###### Time Step Change Factor

Syntax

  Time Step Change Factor {=} Change

Summary

  Specify the factor by which the time step is allowed to increase or decrease between time steps.

Description

  Need a fuller description here.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Change | real | 10.0

###### Transient Step Type

Syntax

  Transient Step Type {=} {automatic | fixed | invalid time step type}

Summary

  Specifies whether to use fixed time-stepping or automatic time-stepping.

Description

  Need a fuller description here.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
FuegoStepType | {automatic | fixed | invalid time step type} | FIXED