/DT/ALE

Engine Keyword Time step control for ALE or EULER cells.

Format

ΔTsca ΔTmin

Definition

Field Contents SI Unit Example
ΔTsca Scale factor on critical time step.

Default = 0.5

ΔTmin Minimum time step. [s]

Comments

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