When doing FSI, it is possible through the keyword ICFD_CONTROL_FSI to trigger one way coupling i.e either only the fluid has an influence on the solid’s displacements or only the solid has an influence on the fluid’s flow pattern. The latter case is often used. However, this implies setting up the solid problem, solving it and communicating the solid’s displacement and velocity to the fluid solver during the run which the fluid solver will then use to up move the volume mesh. In order to reduce calculation time and increase accuracy, it is often wise to directly impose the displacements on the fluid nodes through the use of the ICFD_CONTROL_IMPOSED_MOVE keyword.
Fluid velocity fringes
*DATABASE_BINARY_D3PLOT *DEFINE_CURVE_FUNCTION *DEFINE_CURVE_TITLE *END *ICFD_BOUNDARY_FREESLIP *ICFD_BOUNDARY_PRESCRIBED_VEL *ICFD_BOUNDARY_PRESCRIBED_PRE *ICFD_BOUNDARY_NONSLIP *ICFD_CONTROL_IMPOSED_MOVE *ICFD_CONTROL_TIME *ICFD_DATABASE_DRAG *ICFD_MAT *ICFD_PART *ICFD_PART_VOL *ICFD_SECTION *INCLUDE *KEYWORD *MESH_BL *MESH_SURFACE_ELEMENT *MESH_SURFACE_NODE *MESH_VOLUME *PARAMETER *TITLE
$-----------------------------------------------------------------------------
$
$ Example provided by Iñaki (LSTC)
$
$ E-Mail: info@dynamore.de
$ Web: http://www.dynamore.de
$
$ Copyright, 2015 DYNAmore GmbH
$ Copying for non-commercial usage allowed if
$ copy bears this notice completely.
$
$X------------------------------------------------------------------------------
$X
$X 1. Run file as is.
$X Requires LS-DYNA MPP R9.0.0 (or higher) with double precision
$X
$X------------------------------------------------------------------------------
$# UNITS: Dimensionless.
$X------------------------------------------------------------------------------
$X
*KEYWORD
*TITLE
ICFD Cylinder flow - Imposed Move
*INCLUDE
mesh.k
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$ $
$ PARAMETERS $
$ $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*PARAMETER
R T_end 40.0
R dt_plot 0.50
$
$--- Fluid
$
R v_inlet 1.0
Rrho_fluid 1.0
R mu_fluid 0.005
R dt_fluid 0.050
$
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$ $
$ ICFD CONTROL CARDS $
$ $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*ICFD_CONTROL_TIME
$# ttm dt
&T_end &dt_fluid
*ICFD_CONTROL_IMPOSED_MOVE
$# pid lcidvx lcidvy lcidvz
4 5
*DEFINE_CURVE_FUNCTION
5
2*3.14/10*sin(2*3.14/10*TIME+3.14/2)
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$ $
$ ICFD PARTS/ SECTION/ MATERIAL $
$ $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*ICFD_SECTION
$# sid
1
*ICFD_MAT
$# mid flg ro vis
1 1&rho_fluid &mu_fluid
*ICFD_PART
$# pid secid mid
1 1 1
*ICFD_PART
$# pid secid mid
2 1 1
*ICFD_PART
$# pid secid mid
3 1 1
*ICFD_PART
$# pid secid mid
4 1 1
*ICFD_PART_VOL
$# pid secid mid
10 1 1
$# spid1 spid2 spid3 spid4
1 2 3 4
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$ $
$ ICFD BOUNDARY/INITIAL CONDITIONS $
$ $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*ICFD_BOUNDARY_PRESCRIBED_VEL
$# pid dof vad lcid
1 1 1 1
*ICFD_BOUNDARY_PRESCRIBED_VEL
$# pid dof vad lcid
1 2 1 2
*ICFD_BOUNDARY_PRESCRIBED_PRE
$# pid lcid sf death birth
2 2
*ICFD_BOUNDARY_FREESLIP
$# pid
3
*ICFD_BOUNDARY_NONSLIP
$# pid
4
*DEFINE_CURVE_TITLE
Velocity inlet
$# lcid sidr sfa sfo offa offo dattyp
1
$# a1 o1
0.0 0.
5.0 0.
6.0 &v_inlet
10000.0 &v_inlet
*DEFINE_CURVE_TITLE
Pressure outlet
$# lcid sidr sfa sfo offa offo dattyp
2
$# a1 o1
0.0 0.0
10000.0 0.0
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$ $
$ ICFD MESH KEYWORDS $
$ $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*MESH_VOLUME
$# volid
10
$# pid1 pid2 pid3 pid4
1 2 3 4
*MESH_BL
$# pid nelth
4 2
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$ $
$ DATABASE (OUTPUT) $
$ $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*ICFD_DATABASE_DRAG
$# pid
4
*DATABASE_BINARY_D3PLOT
&dt_plot
*END
When doing FSI, it is possible through the keyword ICFD_CONTROL_FSI to trigger one way coupling i.e either only the fluid has an influence on the solid’s displacements or only the solid has an influence on the fluid’s flow pattern. The latter case is often used. However, this implies setting up the solid problem, solving it and communicating the solid’s displacement and velocity to the fluid solver during the run which the fluid solver will then use to up move the volume mesh. In order to reduce calculation time and increase accuracy, it is often wise to directly impose the displacements on the fluid nodes through the use of the ICFD_CONTROL_IMPOSED_MOVE keyword.