/ALE/GRID
Block Format Keyword This card enables grid formulation for ALE modeling. The ALE domain can have moving boundaries.
The grid must also be updated on each cycle to map the new geometric domain. This update is not unique and can be arbitrary. Grid points are updated at each cycle depending on formulation type defined.
Format
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| /ALE/GRID/FormulationType | |||||||||
Definition
- Formulation Type
- Description
- DISP
- Average displacement.
- DONEA
- Donea formulation.
- LAPLACIAN
- Laplacian grid smoothing method.
- SPRING
- Springs are introduced on cell edges to avoid locally small mesh size.
- STANDARD
- Advanced formulation with edge spring and anti-shear spring to avoid small mesh size and flat cells.
- VOLUME
- Volume based grid smoothing.
- ZERO
- Grid is not updated.
Comments
- ALE formulation is activated for a given material using /ALE/MAT card.
- If an /ALE/GRID card is not specified, the ALE grid formulation is automatically set as Donea (/ALE/GRID/DONEA), with default values.
- The purpose of grid formulation is to update grid points with evolution of the
ALE domain caused by moving boundaries (illustrated below). Grid velocities are also
computed with a dependency on Lagrangian node velocities. Material inside the domain is
not affected since it is remapped inside the new grid configuration at each cycle. Some
domain evolution may lead to small cell and then numerical strategies can be introduced to
mitigate time step decrease (example:/ALE/GRID/STANDARD).
Figure 1. - Specific rules for grid velocity of given points can also be defined by introducing links (/ALE/LINK/VEL). This enables linking grid velocity to specific main nodes.
- A given point from ALE domain can be defined as a Lagrangian node (/ALE/BCS).
- A given grid point can be fixed in all or specific directions (/ALE/BCS).
- To fix material at a given point in a specified direction (/BCS).