/ALE/GRID

Block Format Keyword

/ALE/GRID/FormulationType

Description

This card enables to define grid formulation for ALE modeling. ALE domain can have moving boundaries. Grid must also be updated on each cycle to map the new geometrical domain. This update is not unique and can be arbitrary. Grid points are updated on each cycle depending on formulation type provided by you.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/ALE/GRID/FormulationType

FormulationType	Description
ZERO	Grid is not updated.
DONEA	Donea Formulation.
DISP	Average Displacement.
SPRING	Spring 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.

1.	ALE formulation is activated for a given material using /ALE/MAT card.

2.	By default grid velocity is not computed. This is equivalent to /ALE/GRID/ZERO. This formulation also enables to switch to an Eulerian formulation.

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 prevent time step to decrease (example:/ALE/GRID/STANDARD).

ale_grid

4.	Specific rules for grid velocity of given points can also be defined by introducing links (/ALE/LINK/VEL). This enables to link grid velocity to specific master nodes.

5.	A given point from ALE domain can be defined as a Lagrangian node (/ALE/BCS).

6.	A given grid point can be fixed in all or specific directions (/ALE/BCS).

7.	To fix material at a given point in a specified direction (/BCS).