# Basics : Periodic Couette Flow — Welcome to LS-DYNA Examples

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This simple example uses the classic Couette flow application to introduce the rotational periodic boundary condition feature. Both the velocity and the pressure are constrained between the two opposing faces. Non matching meshes are possible.

## Animated Result

Fluid velocity fringes

## Keywords

```*KEYWORD
*TITLE
*DATABASE_BINARY_D3PLOT
*DEFINE_CURVE_TITLE
*ICFD_BOUNDARY_PERIODIC
*ICFD_BOUNDARY_PRESCRIBED_VEL
*ICFD_BOUNDARY_FREESLIP
*ICFD_CONTROL_TIME
*ICFD_CONTROL_OUTPUT
*ICFD_DEFINE_POINT
*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 Dev 130100 (or higher) with double precision
\$X
\$X------------------------------------------------------------------------------
\$# UNITS: Dimensionless.
\$X------------------------------------------------------------------------------
\$X
*KEYWORD
*TITLE
ICFD Couette flow
*INCLUDE
mesh3.k
\$mesh2.k
\$mesh1.k
\$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
\$ \$
\$ PARAMETERS \$
\$ \$
\$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*PARAMETER
R T_end 30.
R dt_plot 0.2
\$
\$--- Fluid
\$
R w_1 1.0
R w_2 -2.0
R angle 120.
Rrho_fluid 1.00
R mu_fluid 0.02
R dt_fluid 0.02
\$---+----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_OUTPUT
3
\$---+----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
\$# pid secid mid
5 1 1
*ICFD_PART_VOL
\$# pid secid mid
10 1 1
\$# spid1 spid2 spid3 spid4 spid5
1 2 3 4 5
\$---+----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 3 2 13 1 1
*ICFD_DEFINE_POINT
1 0 0 0
*ICFD_BOUNDARY_PRESCRIBED_VEL
2 3 2 14 1 1
*ICFD_BOUNDARY_PERIODIC
\$# pidmast pertype pidslav axe ptid angle
4 1 3 3 1 &angle
*ICFD_BOUNDARY_FREESLIP
5
*DEFINE_CURVE
13
0,&w_1
1000,&w_1
*DEFINE_CURVE
14
0,&w_2
100,&w_2
\$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
\$ \$
\$ ICFD MESH KEYWORDS \$
\$ \$
\$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*MESH_VOLUME
10
1,2,3,4,5
\$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
\$ \$
\$ DATABASE (OUTPUT) \$
\$ \$
\$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*DATABASE_BINARY_D3PLOT
&dt_plot
*END```