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# TIMESTEPPER¶

Specifies time step acceleration, maximum number of time steps, etc.

## Required Cards:¶

- TIMESTEPPER <string>
- Specifies the type of timestepper, where <string> is FLOW or TRANSPORT.

## Optional Cards:¶

- NUM_STEPS_AFTER_CUT <int>
- Number of time steps after a time step cut that the time step size must be held constant
- MAX_STEPS <int>
- Maximum time step after which the simulation will be terminated
- TS_ACCELERATION <int>
- Integer indexing time step acceleration ramp (
**expert users only**). Use in conjunction with DT_FACTOR. - MAX_TS_CUTS <int>
- Maximum number of consecutive time step cuts before the simulation is
terminated with plot of the current solution printed to a
`XXX_cut_to_failure.tec`

file for debugging. - DT_FACTOR <float array>
- Array of floating point numbers of tfac array (
**expert users only**). Values specify time step multiplier as a function of number of Newton iterations in consecutive order from 1 Newton iteration to TS_ACCELERATION Newton iterations. - TIMESTEP_REDUCTION_FACTOR <float>
- The factor by which the time step will be reduced when it is cut (default: 0.5).
- TIMESTEP_MAXIMUM_GROWTH_FACTOR <float>
- The maximum factor by which the time step can be increased between time steps (default: 2.).
- INITIALIZE_TO_STEADY_STATE
- Flag requesting that a steady state solution be computed based on boundary and
initial conditions at the beginning of the simulation (
**Warning: not robust**) - RUN_AS_STEADY_STATE
- Flag indicating that the simulation is to be run as steady state
(
**Warning: not robust**)

## Examples¶

TIMESTEPPER FLOW TS_ACCELERATION 8 MAX_STEPS 10000 ! terminates simulation after 10,000 time steps MAX_TS_CUTS 5 ! terminates simulation after 5 consecutive time step cuts END