# 3D Piston Problem — Welcome to LS-DYNA Examples

Home » Knowledge Base » CESE / DUAL-CESE » Examples DUAL-CESE » 3D Piston Problem

In this 3D fluid-structure interaction (FSI) example, the flow field inside the piston chamber is simulated during the valve’s back and forth motion. Here the dual CESE FSI-mmm solver is used, which is based on the moving mesh method (mmm). This method is more suitable for small deformation problems.

## Description

In this 3D fluid-structure interaction (FSI) example, the flow field inside the piston chamber is simulated during the valve’s back and forth motion. Here the dual CESE FSI-mmm solver is used, which is based on the moving mesh method (mmm). This method is more suitable for small deformation problems.

## Keywords

*DUALCESE_MODEL

*DUALCESE_CONTROL_SOLVER

*DUALCESE_CONTROL_TIMESTEP

*DUALCESE_CONTROL_LIMITER

*DUALCESE_INCLUDE_MODEL

*DUALCESE_BOUNDARY_SLIDING_SEGMENT_SET

*DUALCESE_BOUNDARY_REFLECTIVE_SEGMENT_SET

*DUALCESE_BOUNDARY_FSI_SEGMENT_SET

*DUALCESE_INITIAL

*DUALCESE_PART

*DUALCESE_CONTROL_MESH_MOV

*DUALCESE_MAT_GAS

*DUALCESE_EOS_IDEAL_GAS

*DUALCESE_D3PLOT

*CONTROL_TERMINATION

*DATABASE_BINARY_D3PLOT

*DATABASE_BINARY_D3DUMP

*INCLUDE

*PART

*SECTION_BEAM

*SECTION_SOLID

*MAT_LINEAR_ELASTIC_DISCRETE_BEAM

*MAT_ELASTIC

*HOURGLASS

*DEFINE_CURVE

## Reduced Input

*KEYWORD

\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$

*DUALCESE_CONTROL_SOLVER

\$    ieqns     igeom iframeref

Euler        3D     fixed

\$        NS        3D     fixed

*DUALCESE_CONTROL_TIMESTEP

\$     iddt       cfl     dtint

2       0.9    0.1e-5

*DUALCESE_CONTROL_LIMITER

\$    idlmt      alfa      beta      epsr

0      1.        1.0      0.001

*DUALCESE_INCLUDE_MODEL

fluid_mesh.k

\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$

\$ Setup the boundary conditions for fluid

*DUALCESE_BOUNDARY_SLIDING_SEGMENT_SET

\$     ssid

7

\$*DUALCESE_BOUNDARY_SOLID_WALL_SEGMENT_SET

*DUALCESE_BOUNDARY_REFLECTIVE_SEGMENT_SET

\$     ssid

2

*DUALCESE_BOUNDARY_FSI_SEGMENT_SET

\$     ssid     ref_p

10.774723e5

\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$

\$ Setup the initial conditions for fluid

*DUALCESE_INITIAL

\$      uic       vic       wic     rhoic       pic       tic       hic

0.0       0.0       0.0   0.967860.774723e5

\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$

\$ Setup fluid properties

*DUALCESE_PART

\$      pid       mid     eosid  FSI-type MOVMSHALG

1         4         3       MMM      21

*DUALCESE_CONTROL_MESH_MOV

\$       ID      IALG     NITER RELERRTOL  MXDISP_R

21         9                       1.e-3

*DUALCESE_MAT_GAS

\$      mid        c1        c2      prnd

4  1.458e-6     110.4      0.72

*DUALCESE_EOS_IDEAL_GAS

\$    eosid        cv        cp        t0        v0

3     713.5    1001.5

\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$

\$ Handle output of state and restart data

*DUALCESE_D3PLOT

density

pressure

velocity

\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$

*END