Basics : Cylinder flow — Welcome to LS-DYNA Examples

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This LS-DYNA simulation shows a simple ICFD input deck with a coarse mesh. The inflow is characterized by a prescribed velocity while the reference pressure has been set to 0 for the outlet (undisturbed flow). For the far field domain, a freeslip boundary condition has been used, stipulating that the normal component of the velocity is null while the tangential is left free. For those conditions to be physically valid, they need to be put far away for the object of interest in this case the cylinder. The volume mesh is generated automatically and a boundary layer mesh has been applied to the cylinder in order to better capture the velocity gradient close to the wall.

Description and Tutorial

This LS-DYNA simulation shows a simple ICFD input deck with a coarse mesh. The inflow is characterized by a prescribed velocity while the reference pressure has been set to 0 for the outlet (undisturbed flow). For the far field domain, a freeslip boundary condition has been used, stipulating that the normal component of the velocity is null while the tangential is left free. For those conditions to be physically valid, they need to be put far away for the object of interest in this case the cylinder. The volume mesh is generated automatically and a boundary layer mesh has been applied to the cylinder in order to better capture the velocity gradient close to the wall.

 

Watch the tutorial on YouTube

 

Animated Result

Fluid velocity fringes

ezgif.comvideotogif.gif

 

Keywords

*DATABASE_BINARY_D3PLOT
*DEFINE_CURVE_TITLE
*END
*ICFD_BOUNDARY_FREESLIP
*ICFD_BOUNDARY_PRESCRIBED_VEL
*ICFD_BOUNDARY_PRESCRIBED_PRE
*ICFD_BOUNDARY_NONSLIP
*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

Reduced Input

$-----------------------------------------------------------------------------
$
$ 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: Dimensionless. 
$X------------------------------------------------------------------------------
$X
*KEYWORD
*TITLE
ICFD Cylinder flow
*INCLUDE
mesh.k
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$                                                                              $
$                             PARAMETERS                                       $
$                                                                              $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*PARAMETER
R    T_end     100.0
R  dt_plot      1.00
$
$--- Fluid
$
R  v_inlet       1.0
Rrho_fluid       1.0
R mu_fluid     0.005 
R dt_fluid     0.000
$
$---+----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
$---+----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                    &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
*DATABASE_BINARY_D3PLOT
&dt_plot
*END

Figures

Cylinder Flow

 

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