Basics : Turbulent flow — Welcome to LS-DYNA Examples

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This LS-DYNA simulation shows a turbulent flow input deck. The fluid and boundary conditions give a Reynolds number of 50 000 making the flow turbulent and prompting the use of a turbulence model. The default configuration uses a RANS realizable model. The boundary layer mesh has been chosen in accordance, to yield an approximate Y+ value of 30. Several other turbulence models can be tried and the boundary layer mesh changed accordingly. The user can study the length and effects of the recirculation zone over the thick plate.

Description

This LS-DYNA simulation shows a turbulent flow input deck. The fluid and boundary conditions give a Reynolds number of 50 000 making the flow turbulent and prompting the use of a turbulence model. The default configuration uses a RANS realizable model. The boundary layer mesh has been chosen in accordance, to yield an approximate Y+ value of 30. Several other turbulence models can be tried and the boundary layer mesh changed accordingly. The user can study the length and effects of the recirculation zone over the thick plate.

Animated Result

Turbulent intensity fringes

ezgif.comvideotogif.gif

 

Keywords

*DATABASE_BINARY_D3PLOT
*KEYWORD
*TITLE
*DEFINE_CURVE_TITLE
*ICFD_BOUNDARY_FREESLIP
*ICFD_BOUNDARY_PRESCRIBED_PRE
*ICFD_BOUNDARY_PRESCRIBED_VEL
*ICFD_BOUNDARY_PRESCRIBED_TURBULENCE
*ICFD_BOUNDARY_NONSLIP
*ICFD_CONTROL_OUTPUT
*ICFD_CONTROL_TAVERAGE
*ICFD_CONTROL_TIME
*ICFD_CONTROL_TURBULENCE
*ICFD_DATABASE_DRAG
*ICFD_DATABASE_TIMESTEP
*ICFD_INITIAL
*ICFD_MAT
*ICFD_PART
*ICFD_PART_VOL
*ICFD_SECTION
*INCLUDE
*MESH_BL
*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
$
$ 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 R9.0.0 (or higher) with double precision 
$X
$X------------------------------------------------------------------------------
$# UNITS: (kg/m/s)
$X------------------------------------------------------------------------------
$X
*KEYWORD
*TITLE
ICFD Turbulent thick plate
*INCLUDE
mesh.k
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$                                                                              $
$                             PARAMETERS                                       $
$                                                                              $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*PARAMETER
R    T_end       2.0
R  dt_plot      0.05
$
$--- Fluid
$
R  v_inlet      8.33
Rrho_fluid   1.22500
R mu_fluid 1.7895e-5 
R dt_fluid      1e-4
R  mu_turb       1e4
$
$---+----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_TURBULENCE
$ RANS realizable k-epsilon
$#    tmod    submcd      wlaw    
         1         2         1            
$ LES Smagorinsky
$2
$ RANS Menter-SST
$4,3
*ICFD_CONTROL_TAVERAGE
$#      dt
         1
*ICFD_CONTROL_OUTPUT
$#    mslv
         3
*ICFD_CONTROL_MESH
$#    mgsf              mstrat   2dstruc
                                       1
$---+----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_TURBULENCE
$#     pid     vtype       imp      lcid 
         1         2         2         3
*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
*ICFD_INITIAL
$#     pid        vx
         0  &v_inlet
*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
*DEFINE_CURVE_TITLE
inlet turbulent viscosity
$#    lcid      sidr       sfa       sfo      offa      offo    dattyp
         3                    &mu_turb
$#                a1                  o1
                 0.0                 1.0
             10000.0                 1.0
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$                                                                              $
$                            ICFD MESH KEYWORDS                                $
$                                                                              $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*MESH_VOLUME
$#   volid     
         8
$#    pid1      pid2      pid3      pid4           
         1         2         3         4
*MESH_BL
$#     pid     nelth      blth      blfe      blst
         4         2     0.006                   1
$ For LES and possibly RANS k-w
$$#     pid     nelth      blth      blfe      blst
$         4         5     0.006      1e-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
*ICFD_DATABASE_TIMESTEP
$#   outlv
         1
*DATABASE_BINARY_D3PLOT
&dt_plot
*END

Figures

Cylinder Flow

 

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