An air flow passes over a building preloaded by gravity. Non linear vibrations due to fluid structure interaction occur. The viscosity has been artificially raised to avoid turbulent non linearities.
Fluid velocity fringes
*KEYWORD *TITLE *BOUNDARY_SPC_SET_BIRTH_DEATH *CONTROL_IMPLICIT_DYNAMICS *CONTROL_IMPLICIT_GENERAL *CONTROL_IMPLICIT_SOLUTION *CONTROL_TERMINATION *DATABASE_BINARY_D3PLOT *DATABASE_HISTORY_NODE *DATABASE_NODOUT *DEFINE_CURVE_TITLE *DEFINE_FUNCTION *ELEMENT_SHELL *ICFD_BOUNDARY_FREESLIP *ICFD_BOUNDARY_FSI *ICFD_BOUNDARY_NONSLIP *ICFD_BOUNDARY_PRESCRIBED_VEL *ICFD_BOUNDARY_PRESCRIBED_PRE *ICFD_CONTROL_FSI *ICFD_CONTROL_LOAD *ICFD_CONTROL_OUTPUT *ICFD_CONTROL_TIME *ICFD_DATABASE_DRAG *ICFD_DATABASE_POINTOUT *ICFD_MAT *ICFD_PART *ICFD_PART_VOL *ICFD_SECTION *INCLUDE *LOAD_BODY_Y *MAT_ELASTIC *MESH_BL *MESH_SURFACE_ELEMENT *MESH_SURFACE_NODE *MESH_VOLUME *NODE *PARAMETER *PART *SECTION_SHELL *SET_NODE_LIST *END
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$X------------------------------------------------------------------------------
$X
$X 1. Run file as is.
$X Requires LS-DYNA MPP R8.0.0 (or higher) with double precision
$X
$X------------------------------------------------------------------------------
$# UNITS: (kg/m/s)
$X------------------------------------------------------------------------------
$X
*KEYWORD
*TITLE
ICFD Flow over a building with elastic membrane roof
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$ $
$ PARAMETERS $
$ $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*PARAMETER
R T_end 50.0
R dt_plot 0.25
R fsi_bt 20.
$
$--- Fluid
$
R v_max 35.
Rrho_fluid 1.18
R mu_fluid 0.1
R dt_fluid 0.005
*INCLUDE
mesh.k
*INCLUDE
struc.k
$---+----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_FSI
$# owc bt
0 &fsi_bt
*ICFD_CONTROL_OUTPUT
$# mslv
4
*ICFD_CONTROL_LOAD
$# abl
$---+----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
$# pid secid mid
6 1 1
*ICFD_PART
$# pid secid mid
7 1 1
*ICFD_PART
$# pid secid mid
8 1 1
*ICFD_PART_VOL
$# pid secid mid
10 1 1
$# spid1 spid2 spid3 spid4 spid5 spid6 spid7 spid8
1 2 3 4 5 6 7 8
$---+----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
*ICFD_BOUNDARY_NONSLIP
$# pid
5
*ICFD_BOUNDARY_NONSLIP
$# pid
6
*ICFD_BOUNDARY_NONSLIP
$# pid
7
*ICFD_BOUNDARY_NONSLIP
$# pid
8
*ICFD_BOUNDARY_FSI
$# pid
6
*DEFINE_FUNCTION
$# dfid
1
$# function
float h(float y, float time)
{
float fac,trise;
trise = 2;
fac = 1.0;
return v_max*(y/350)**0.22;
}
*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
10
$# pid1 pid2 pid3 pid4 pid5 pid6 pid7 pid8
1 2 3 4 5 6 7 8
*MESH_BL
$# pid nelth
6 1
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$ $
$ DATABASE (OUTPUT) $
$ $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*ICFD_DATABASE_DRAG
$# pid
5
*ICFD_DATABASE_DRAG
$# pid
6
*ICFD_DATABASE_DRAG
$# pid
7
*ICFD_DATABASE_POINTOUT
$# outlv
1
$# pid x y z
1 67.5 5.3
*DATABASE_BINARY_D3PLOT
&dt_plot
*END
An air flow passes over a building preloaded by gravity. Non linear vibrations due to fluid structure interaction occur. The viscosity has been artificially raised to avoid turbulent non linearities.
References :
[1] B. Hübner, E. Walhorn, and D. Dinkler, “A monolithic approach to fluid–structure interaction using space–time finite elements,” Computer Methods in Applied Mechanics and Engineering, vol. 193, no. 23–26, pp. 2087 – 2104, 2004.