/INTER/TYPE18

Block Format Keyword This interface manages indirect coupling between ALE and Lagrange for FSI applications. A penalty method is used and requires stiffness and gap values.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/INTER/TYPE18/inter_ID
inter_title
  surf_ID grbric_ID       Ipres Idel    
Stfval     Gap Tstart Tstop
        VISs     Bumult
Blank Format

Definitions

Field Contents SI Unit Example
inter_ID Interface identifier.

(Integer, maximum 10 digits)

  
inter_title Interface title.

(Character, maximum 100 characters)

  
surf_ID Lagrangian surface identifier.

(Integer)

  
grbric_ID Eulerian or ALE brick elements group identifier. Used for 3D analysis.

(Integer)

  
Ipres Pressure correction flag.
= 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.

(Integer)

  
Idel Node and segment deletion flag.
= 0 (Default)
No deletion.
= 1
When all the elements (4-node shells, 3-node shells, solids) associated to one segment are deleted, the segment is removed from the Lagrangian side of the interface.
Additionally, non-connected nodes are removed from the Eulerian or ALE 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 Lagrangian side of the interface.
Additionally, non-connected nodes are removed from the Eulerian or ALE side of the interface.

(Integer)

  
Stfval Interface stiffness value. 3

(Real)

 [ N m ]
Gap Interface gap. 4

(Real)

 [ m ]
Tstart Start time.

(Real)

 [ s ]
Tstop Time for temporary deactivation.

(Real)

 [ s ]
VISs Critical damping coefficient on interface stiffness.

(Real)

  
Bumult Sorting factor to speed up the sorting algorithm.

Default set to 0.20 (Real)

  

Comments

  1. In case of SPMD parallelization, each Lagrangian segment defined by surf_ID must be associated with an element which could be a void element assigned /PROP/VOID.
  2. 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.
  3. Recommended value of Stfval is:(1)
    S t f v a l = ρ ⋅ v 2 ⋅ S e l G a p MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4uaiaads hacaWGMbGaamODaiaadggacaWGSbGaeyypa0ZaaSaaaeaacqaHbpGC cqGHflY1caWG2bWaaWbaaSqabeaacaaIYaaaaOGaeyyXICTaam4uam aaBaaaleaacaWGLbGaamiBaaqabaaakeaacaWGhbGaamyyaiaadcha aaaaaa@4A6C@
    Where,
    ρ
    The (highest) fluid density
    ν
    Estimated relative velocity of the phenomenon
    S e l
    Average surface area of the Lagrangian elements
    • If the fluid is incompressible (ditching, sloshing), use the relative velocity between the Lagrangian surface and the Eulerian or ALE nodes (for example, in ditching it will be the initial velocity of the structure).
    • If:
      • The fluid is compressible but the velocity of the phenomenon is not supersonic, use the highest sound speed among the Eulerian or ALE material nodes (for example, if water and air, refer to water)
      • Compressible and transonic (for example: 0.9 < Mach < 1.1), replace:

        S t f v a l = ρ ⋅ v 2 ⋅ S e l G a p MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4uaiaads hacaWGMbGaamODaiaadggacaWGSbGaeyypa0ZaaSaaaeaacqaHbpGC cqGHflY1caWG2bWaaWbaaSqabeaacaaIYaaaaOGaeyyXICTaam4uam aaBaaaleaacaWGLbGaamiBaaqabaaakeaacaWGhbGaamyyaiaadcha aaaaaa@4A6C@ with S t f v a l = ρ ⋅ v ⋅ c ⋅ S e l G a p MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4uaiaads hacaWGMbGaamODaiaadggacaWGSbGaeyypa0ZaaSaaaeaacqaHbpGC cqGHflY1caWG2bGaeyyXICTaam4yaiabgwSixlaadofadaWgaaWcba GaamyzaiaadYgaaeqaaaGcbaGaam4raiaadggacaWGWbaaaaaa@4CAB@

        Where,
        ν
        Speed of the phenomenon
        c
        Speed of sound in the fluid
        S e l
        Average surface area of the Lagrangian elements
      • 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.
  4. Gap is the interface gap, recommended value is 1.5 times of fluid element size along the normal direction to contact.
  5. Prior to version 2020, the fluid Eulerian or ALE nodes were defined using a grnd_IDs in line 1 field 1. This input format is still supported for legacy models.