Imposing the direction of surface motion

Imposing the direction of surface motion

Ver: 1

DESCRIPTION

With the 'Surface Kinematic condition', the shape of free surfaces and moving interfaces is described by means of a geometrical unknown which controls the motion of points (which belong to the free surface or interface) in a given direction.

By default, those directions of motion are evaluated as the normal to the interface or the free surface.

However, in some situations, the motion of points on the free surface or interface can be restricted in a direction. This is true when the directions of motion computed a priori would generate a deformation of the free surface or interface which is incompatible with the boundary conditions on adjacent boundary sets (typically, planes of symmetry).

For such cases, the user can impose components of the direction of motion at those borders.

By default, direction vectors are also reevaluated at each step in evolutionary and transient tasks. The user may specify that the directions be calculated once and only once for the task. This may be useful for imposing the stability of the algorithm.

OPTIONS

-2
Calculate D once for the whole task

Disables the recalculation of the direction of motion at each step of a transient or evolution scheme. Here, 'D' stands for the direction of motion.

-1
Accept the current conditions

0
Define a condition along the whole surface

Select this option if the common direction of motion D must be imposed along the whole moving surface or interface.

i'
Add a condition on intersection with boundary/subdomain j

Select this option if a condition on the direction of motion D must be added along the intersection of the free surface or interface with boundary/subdomain j.

i"
Add a/Modify condition on intersection with boundary/subdomain j

Select this option if the condition on the direction of motion D must be modified along the intersection of the free surface or interface with boundary/subdomain j.

NOTES The 'Line Kinematic condition' does not make use of directors. Constraints on the directors have not effect on the displacement of a moving surface controlled by the 'Line Kinematic condition'. SEE ALSO

Free Surfaces (UM)
remeshing technique
Evolution (UM)

-2	Calculate D once for the whole task
	Disables the recalculation of the direction of motion at each step of a transient or evolution scheme. Here, 'D' stands for the direction of motion.
-1	Accept the current conditions
0	Define a condition along the whole surface
	Select this option if the common direction of motion D must be imposed along the whole moving surface or interface.
i'	Add a condition on intersection with boundary/subdomain j
	Select this option if a condition on the direction of motion D must be added along the intersection of the free surface or interface with boundary/subdomain j.
i"	Add a/Modify condition on intersection with boundary/subdomain j
	Select this option if the condition on the direction of motion D must be modified along the intersection of the free surface or interface with boundary/subdomain j.