Any trick about FSI setup in Ansys ?

[micspin]

Hi guys!!!
I'm trying to run a Fluid Solid Interaction simulatioin in Ansys but as soon as i launch the solver, this message goes on bothering me:
"Number of Fluid/Structure interfaces do not match for FSIN boundary conditions"

I followed what the tutorial suggests about the set-up problem but i can't get out of it.

Enjoy

Michele

 

[reetu123]

Hi

You have to set up a the interface on each field: one for fluid and one for solid. And both should have the same number (say 1). Sometimes, however, there are issues ever after doing so because Ansys probably is not able to identify the fluid and solid elements separately at the interface.
A good way to deal with this is to create the fluid and solid input files separately. Each file should be created as if the other element does not exist: i.e. element numbering should start from 1 in each file, material type starts from 1 in the solids file. In the fluid file, you specify the fluid properties using fldata command. Each input file should be self sufficient. in the fluid file, specify the fluid solution options. At the end of each input file, issue the cdwrite command to create the cdb files for fluid and solid. Then do mfimport for both files (the manual explains that), and issue the multifield analysis commands.

Hope this helps..this method has helped me a lot.

 

[reetu123]

In addition:
When you issue mfimport commands, you do not need mfel commands..so issue all other commands for multifield analysis except the mfel commands. Also, do the import for fluids file last...in the following order
mfimport,2,solid,cdb
mfimport,1,fluid,cdb

 

[reetu123]

In addition:
When you issue mfimport commands, you do not need mfel commands..so issue all other commands for multifield analysis except the mfel commands. Also, do the import for fluids file last...in the following order
mfimport,2,db,solid,cdb
mfimport,1,db,fluid,cdb

 

[ansysfreak]

Hi

Could anyone give me in input listing of a fluid struc multi field analysis. Because I find it difficult to see the procedure of this analysis.

Thanks
Garry

 

[reetu123]

Here it is



mfimport,2,db,solid,cdb
mfimport,1,db,fluid,cdb
tstep=.5e-3
endt=0.06
n_steps=endt/tstep
/solu

MFAN,ON,MFSC
morph,off
antype,4
nlgeom,1
!* ! Turn on Multifield solver
mffname,1,fluid ! Name the fluid field
mffname,2,solid ! Name the structural field
mfcmmand,1
mfcmmand,2
mforder,1,2 ! Solution order..

MFIN,NONC
MFBU,ON,50,
MFTO,OFF,1e-006,
MFOR, 1, 2

MFSU, 1, 2,DISP, 1
MFSU, 1, 1,FORC, 2


MFIT,40,1,5,
MFIN,NONC
MFBU,ON,50,
MFTO,OFF,0,
!*
MFCO,ALL,0.1,
!*
MFRE,ALL,0.5,RELX
MFTI,endt,
MFDT,tstep,tstep,.01,0
MFRS,0,
!*
MFCA, 1,1,
MFOU,1,
!*
MFCL,SOLU, ,
solve