/DT/ALE

Engine Keyword Time step control for ALE or EULER cells.

Format

$\text{Δ}{T}_{sca}$ $\text{Δ}{T}_{\mathrm{min}}$

Definitions

Field Contents SI Unit Example
$\text{Δ}{T}_{sca}$ Scale factor on critical time step.

Default = 0.5

$\text{Δ}{T}_{\mathrm{min}}$ Minimum time step.

1. If the ALE time step becomes less than $\text{Δ}{T}_{\mathrm{min}}$ , then the simulation will stop and a restart file will be written.
2. As of the 2018.0 release, /DT/BRICK and /DT/QUAD are only relevant for Lagrangian elements.
3. As of the 2018.0 release, time step for ALE or EULER cells can only be controlled with /DT/ALE. This allows the time step control for the ALE cells to be different when you have both Lagrangian and ALE bricks in the input file.
4. By default, scale factor $\text{Δ}{T}_{sca}$ is 0.5 which is the recommended value for ALE or EULER cells. As a result, if you did not use /DT or /DT/BRICK or /DT/QUAD with $\text{Δ}{T}_{sca}$ =0.5, you will have by default, different time step from version 2018.0. To retrieve your previous result, you must set the relevant time step with /DT/ALE.
2017.0 Engine File
2018.0 Engine File
/DT/BRICK with $\text{Δ}{T}_{sca}$ =0.3
Add /DT/ALE with $\text{Δ}{T}_{sca}$ =0.3
/DT/QUAD with $\text{Δ}{T}_{sca}$ =0.0
Add /DT/QUAD with $\text{Δ}{T}_{sca}$ =0.9
/DT with $\text{Δ}{T}_{sca}$ =0.4
Not applicable
No time step control
Add /DT/ALE with $\text{Δ}{T}_{sca}$ =0.9 (3D case), or
$\text{Δ}{T}_{sca}$ =0.67 (2D case)