/INTER/TYPE18

Block Format Keyword

/INTER/TYPE18 - Interface Type 18 (Euler/Lagrange or ALE/Lagrange)

Description

This interface describes the Euler/Lagrange or ALE/Lagrange contact. Euler-Lagrange or ALE-Lagrange contact is the contact between a Lagrangian master surface and a list of Eulerian or ALE slaves nodes. Material velocity for all slave nodes is imposed by master surface with a penalty formulation. ALE slave node grid velocity is not modified by this interface.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/INTER/TYPE18/inter_ID
inter_title
grnd_IDs	surf_IDL					Ibag	Idel
Stfval				Gap		Tstart		Tstop
				VISS				Bumult
Blank Format

Field	Contents	SI Unit Example
inter_ID	Interface identifier (Integer, maximum 10 digits)
inter_title	Interface title (Character, maximum 100 characters)
grnd_IDs	Slave nodes group identifier (Eulerian or ALE nodes) (Integer)
surf_IDL	Lagrangian master surface identifier (Integer)
Ibag	Pressure correction flag (Integer) = 0: no pressure correction = 1: reduce pressure by median pressure = 2: reduce pressure by mean surface pressure = 3: reduce pressure by mean estimated volumetric pressure
Idel	Node and segment deletion flag (Integer) = 0: no deletion (default) = 1: when all the elements (4-node shells, 3-node shells, solids) associated to one segment are deleted, the segment is removed from the master side of the interface. Additionally, non-connected nodes are removed from the slave side of the interface. = 2: when a 4-node shell, a 3-node shell or a solid element is deleted, the corresponding segment is removed from the master side of the interface. Additionally, non-connected nodes are removed from the slave side of the interface.
Stfval	Interface stiffness value (Comment 4) (Real)
Gap	Interface gap (Comment 5) (Real)
Tstart	Start time (Real)
Tstop	Time for temporary deactivation (Real)
VISS	Critical damping coefficient on interface stiffness (Real)
Bumult	Sorting factor - used to speed up the sorting algorithm. Default set to 0.20 (Real)

1.	In case of SPMD, each master segment defined by surf_IDL must be associated to an element (possibly to avoid element).

2.	The flag Ibag refers to the monitored volume option (/MONVOL).

3.	The default value for Bumult automatically increased to 0.30 for models which have more than 1.5 million nodes and to 0.40 for models with more than 2.5 million of nodes.

4.	Recommended value of Stfval is:

Where,

is the (highest) fluid density

is the estimated relative velocity of the phenomenon

Sel is the average surface area of the Lagrangian elements

•	If the fluid is incompressible (ditching, sloshing), use the relative velocity between the master surface and the slave nodes (for example, in ditching it will be the initial velocity of the structure).

•

If:

o	The fluid is compressible but the velocity of the phenomenon is not supersonic, use the highest sound speed among the slave material nodes (for example, if water and air, refer to water)

o	Compressible and transonic (for example: 0.9 < Mach < 1.1), replace:

with

Where,

v is the speed of the phenomenon

c is the speed of sound in the fluid.

Sel is the average surface area of the Lagrangian elements

o	Compressible and supersonic (that is, Mach > 1), use the velocity of the shockwave (generally, but not always, the impact velocity).

•	For detonation, use the Chapman Jouguet velocity

5.	Gap is the interface gap, recommended value is 1.5 * fluid element size along the normal direction to contact