# Basics : Potential flow — Welcome to LS-DYNA Examples

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Despite its limitations (no boundary layer effects, irrotational flow), the solution given by a potential flow solver is very fast and can be used in certain configuration to give a quick approximation of the fluid flow. In this example, after the solve of the potential flow, the pressure is passed to the solid mechanics solver (linear FSI) and the vibrations of the structure can be analysed.

## Animated Result

Fluid pressure fringes

## Keywords

```*KEYWORD
*TITLE
*DATABASE_BINARY_D3PLOT
*DEFINE_CURVE_TITLE
*ICFD_BOUNDARY_FSI
*ICFD_BOUNDARY_NONSLIP
*ICFD_DATABASE_DRAG
*ICFD_CONTROL_GENERAL
*ICFD_CONTROL_FSI
*ICFD_MAT
*ICFD_PART
*ICFD_PART_VOL
*ICFD_SECTION
*INCLUDE
*MESH_SURFACE_ELEMENT
*MESH_SURFACE_NODE
*MESH_VOLUME
*PARAMETER
*END```

## Reduced Input

```\$-----------------------------------------------------------------------------
\$
\$ Example provided by Iñaki (LSTC)
\$
\$ E-Mail: info@dynamore.de
\$ Web: http://www.dynamore.de
\$
\$ 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 R10.1 (or higher) with double precision
\$X
\$X------------------------------------------------------------------------------
\$# UNITS: SI.
\$X------------------------------------------------------------------------------
\$X
*KEYWORD
*TITLE
ICFD Linear FSI with potential Flow
\$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
\$                                                                              \$
\$                             PARAMETERS                                       \$
\$                                                                              \$
\$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*PARAMETER
R    T_end      10.0
R  dt_plot       0.1
\$
\$--- Fluid
\$
R  v_inlet      50.
Rrho_fluid       1.2
R mu_fluid     1.8-5
R dt_fluid     0.000
\$
\$
\$---Struc
\$
Rrho_struc    7200.0
R  E_struc   20000.0
R nu_struc       0.4
R  stiff_y    7000.0
Rstiff_rot    4000.0
R dt_ascii     0.005
*INCLUDE
struc.k
\$*END
*INCLUDE
mesh.k
\$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
\$                                                                              \$
\$                           ICFD CONTROL CARDS                                 \$
\$                                                                              \$
\$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*ICFD_CONTROL_GENERAL
1         2
*ICFD_CONTROL_FSI
0
*ICFD_BOUNDARY_FSI
4
\$---+----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
1         1         1         1
*ICFD_BOUNDARY_PRESCRIBED_VEL
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                    &v_inlet
\$#                a1                  o1
0.0                 1.0
10000.0                 1.0
*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
1
\$#    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                                                           1
*DATABASE_BINARY_D3PLOT
&dt_plot
*END```