Time¶

Simulation time controls how the model evolves in time — from preparation of the initial state, to advanced scheduling of solver steps, to generating restart points. The time configuration defines:

How the simulation starts (initial conditions)
How the solver adapts the time-step limits throughout the run
When the simulator saves snapshot files for restart or post-processing
The final simulation time

JSON key: time (EN/PT) · tempo (PT) — top-level object

Simulation Mode¶

Choose between steady-state or transient simulation.

transient: false → run only steady-state calculation and stop
transient: true → start with transient simulation

JSON key: initialConfig.transient (EN) · configuracaoInicial.transiente (PT)
Default: false

Initial Condition Strategy¶

Controls how the initial state is established:

Value	Meaning
0	User-defined initial fields
1	Initialize from steady-state solution
2	Restart from snapshot file (`.snp`)
3	Gas-lift unloading initialization

JSON key: initialConfig.initialCondition (EN) · configuracaoInicial.condicaoInicial (PT)
Default: 1

Option 0: User-Defined Initial State¶

Explicitly set initial fluid fields in pipe cells.

JSON key: initialConfig.initialFluidId (EN) · configuracaoInicial.iniFluidoP (PT)

Option 2: Snapshot Restart¶

Initialize the simulation from a snapshot state file.

JSON key: initialConfig.snapshotFile (EN) · configuracaoInicial.SnapShotArq (PT)

Warning

If initialCondition = 2 is selected and the snapshot file does not exist, parsing fails.

Option 3: Gas-Lift Unloading¶

Specialized initialization for gas-lift operations. Requires:

gasLineInterfaceLength · comprimentoMedidoInterfaceLinhaGas
prodLineInterfaceLength · comprimentoMedidoInterfaceLinhaProd
fluidSalinity · SalinidadeFluido

Optionally:

dischargeControl · controleDescarga
dischargeParameters · parametrosDescarga

Time Scheduling¶

Define how the solver advances in time, controls adaptive time-step size, and sets simulation stop conditions.

Core fields:

finalTime · tempoFinal [s]: Total simulated time (when to stop)
times · tempos [s]: Time points where the time-step schedule changes
maxDT · dtmax [s]: Maximum allowed step size for solver between each time interval

The schedule allows piecewise control: between times[i] and times[i+1], the solver will not exceed maxDT[i], though it may choose smaller steps internally for stability.

JSON key: time.finalTime, time.times, time.maxDT

Parser checks:

times must be monotonically increasing and start at 0
times and maxDT arrays must be the same size

Defaults:

If missing, times = [0] and maxDT = [5]

Segregation Scheduling¶

Schedules time windows for special “segregation” mode, used in shutdown or fallback scenarios.

segregationTime (EN) · tempoSegrega (PT): array (s), when mode changes apply
segregation (EN) · segrega (PT): array, mode indicator (0 = normal, 1 = segregation)

Behavior:

If these are omitted, a default schedule is created at t = 0 in segregation mode.

Snapshot Save Times¶

Controls when the simulation saves .snp or .snt snapshot files for restart or analysis.

JSON key: saveSnapshot (EN) · gravaMomento (PT) Each entry is a time [s] at which a snapshot is saved.

Practical Guidance¶

Adaptive scheduling: Define short timesteps for fast transients (startup, shut-down), then relax time-step for slower phases.
Restarts: Use saveSnapshot to schedule checkpoint writes — especially useful before events requiring operator review or slow, manual steps.
Segregation windows: For simulations with production shutdowns, use segregation scheduling to better control step size and convergence during sensitive transitions.

Example: Standard Transient¶

{
  "initialConfig": {
    "transient": true,
    "initialCondition": 1,
    "initialFluidId": 0
  },
  "time": {
    "finalTime": 3600,
    "times": [0, 10, 100],
    "maxDT": [0.1, 1.0, 5.0],
    "saveSnapshot": [1800, 3600]
  }
}

Example: Restart from Snapshot¶

{
  "initialConfig": {
    "transient": true,
    "initialCondition": 2,
    "snapshotFile": "shutdown_3600s.snp"
  },
  "time": {
    "finalTime": 7200,
    "times": [0, 100],
    "maxDT": [1.0, 5.0]
  }
}

Example: Segregation Window¶

{
  "time": {
    "finalTime": 86400,
    "times": [0, 60, 600, 3600],
    "maxDT": [0.5, 2.0, 10.0, 30.0],
    "segregationTime": [0, 600],
    "segregation": [0, 1]
  }
}