/DT/ALE

Engine Keyword Time step control for ALE or EULER cells.

Format

Δ T sca Δ T min

Definitions

Field Description SI Unit Example
Δ T sca Scale factor on critical time step.

Default = 0.5

  
Δ T min Minimum time step.  

Comments

  1. If the ALE time step becomes less than Δ T 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 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 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 Δ T sca =0.3
    Add /DT/ALE with Δ T sca =0.3
    /DT/QUAD with Δ T sca =0.0
    Add /DT/QUAD with Δ T sca =0.9
    /DT with Δ T sca =0.4
    Not applicable
    No time step control
    Add /DT/ALE with Δ T sca =0.9 (3D case), or
    Δ T sca =0.67 (2D case)