An initially loaded spring is released at t=0. A compression wave is formed in the fluid that bounces back and interacts with the structure thus creating an oscillatory system. In this example, the moving mesh technique is used for FSI rather than the classic embedded approach.
CESE Velocity fringes
*BOUNDARY_SPC_SET *CESE_BOUNDARY_FSI_SET *CESE_BOUNDARY_REFLECTIVE_SET *CESE_BOUNDARY_SLIDING_SET *CESE_CONTROL_LIMITER *CESE_CONTROL_MESH_MOV *CESE_CONTROL_SOLVER *CESE_CONTROL_TIMESTEP *CESE_EOS_IDEAL_GAS *CESE_INITIAL *CESE_PART *CONTROL_TERMINATION *DATABASE_BINARY_D3PLOT *DEFINE_CURVE *ELEMENT_BEAM *ELEMENT_SHELL *KEYWORD *MAT_ELASTIC *MAT_LINEAR_ELASTIC_DISCRETE_BEAM *MAT_RIGID *NODE *PARAMETER *PART *TITLE *SECTION_BEAM *SECTION_SHELL *SET_NODE_LIST_TITLE *SET_SEGMENT
$-----------------------------------------------------------------------------
$
$ 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 R8.0.0 (or higher) with double precision
$X
$X------------------------------------------------------------------------------
$# UNITS: (kg/m/s)
$X------------------------------------------------------------------------------
$X
*KEYWORD
*TITLE
CESE Moving mesh Piston example
*INCLUDE
mesh.k
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$ $
$ CESE CONTROL CARDS $
$ $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$
*CESE_CONTROL_SOLVER
$ iframe iflow igeom
100 1 2
*CESE_CONTROL_TIMESTEP
$ iddt cfl dtint
2&cfl_fluid &dt_fluid
*CESE_CONTROL_LIMITER
$ idlmt alfa beta epsr
1 1.0 1.0 0.5
*CESE_CONTROL_MESH_MOV
$ ialg numiter reltol abstol
9 500 1.0e-5 1.0e-5
$
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$ $
$ CESE PARTS/ EOS/ MATERIAL $
$ $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*CESE_PART
$ pid mid eosid
12 3
*CESE_EOS_IDEAL_GAS
$ eosid cv cp
3 &Cv &Cp
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$ $
$ CESE BOUNDARY/INITIAL CONDITIONS $
$ $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*CESE_BOUNDARY_SLIDING_SET
$ ssid
3
*CESE_BOUNDARY_SLIDING_SET
$ ssid
4
*CESE_BOUNDARY_FSI_SET
$ ssid
1
$
*CESE_BOUNDARY_REFLECTIVE_SET
$ ssid
2
$
*CESE_INITIAL
$ uic vic wic rhoic pic tic hic
0.0 0.0 0.0 &ro_1 &P_1
*END