problem diverge

[Juan Luo]

Hello ,

I met the problem diverge in my calculation of the fluid pass throw a cylindre in 3D. I chose the iturbe=0(laminar) and in the file of listing

it showed:

@
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@
@ @@ WARNING: MESH NOT ENOUGH REFINED AT THE WALL
@ ========
@ PHASE 1
@ The mesh does not seem to be enough refined at the wall
@ to be able to run a laminar simulation.
@
@ The last time step at which too large values for the
@ dimensionless distance to the wall (yplus) have been
@ observed is the time step 2
@
@ The minimum value for yplus must be lower than the
@ limit value YPLULI = 0.23810E+01
@
@ Have a look at the distribution of yplus at the wall
@ (with EnSight for example) to conclude on the way
@ the results quality might be affected.
@
@ This warning is only printed at the first two
@ occurences of the problem and at the last time step
@ of the calculation. The vanishing of the message does
@ not necessarily mean the vanishing of the problem.
@
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@

I tried to refine my mesh but because my mesh in micro-scale , I have already put 60 intervals in the direction thickness (1mm),I can't refine it anymore, if not there will be the problem in the stage pre-processor.

Someone can give me some ideas? Thanks a lot.



In fact, I tried to use the modele of iturb=40(Les) evenif it's not my case, but I don't sucessed start the calculation. In the listing:

Lecture du fichier : preprocessor_output
@
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@
@ @@ WARNING : WHEN READING INPUT DATA
@ =========
@ CHOICE OF TIME-SCHEME
@
@ PHASE 1
@ TIME-SCHEME FOR VELOCITY IS SECOND ORDER
@ (THETAV = 0.50E+00)
@ CERTAIN TERMES ARE HOWEVER FIRST ORDER IN TIME WITH
@ THE FOLLOWING SETTINGS:
@
@ parameters ISTMPF ISNO2T ISTO2T IROEXT IVIEXT ICPEXT
@ Values entered 2 1 0 0 0 0
@
@ computation will go on.
@
@ Check the input data given via User Interface or in usini1.
@
@
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@

For the mode Les I need to change other conditions?

[Matthieu Guillaud]

Hello,
 
can you send us your fortran, xml and mesh files.
 
Thank you.
 
Matthieu

[Juan Luo]

Hello,

I sent you first the files which I used , but the mesh files it's very big(812mio), I can't attach there, how could I do?

Thanks a lot.

juan

[Matthieu Guillaud]

Hello,
 
thanks for your files. I forgot to ask you to send your listing file to. Sorry.
For the mesh, you can post it on : http://dl.free.fr/ and send us the link to download it. 
 
For the LES case, I'm not used to use this module so I'll ask people to answer you.
 
 
Regards.
Matthieu

[Juan Luo]

Previously Matthieu Guillaud wrote:

Hello,
 
thanks for your files. I forgot to ask you to send your listing file to. Sorry.
For the mesh, you can post it on : http://dl.free.fr/ and send us the link to download it. 
 
For the LES case, I'm not used to use this module so I'll ask people to answer you.
 

Regards.
Matthieu

Hello Matthieu,
I've already sent the file of my mesh on: http://dl.free.fr/p7CmPdYcE
Thank you again.
juan

[Matthieu Guillaud]

Hello,
 
thank you for the listing.
At the end of it you have informations on the time step.
Your CFL number (on the listing "Courant max") is too high. It should be around 5.
So you have to change your time step in order to reduce it.
 
It's very high because your inlet velocity is around 4m/s and your mesh cells are very small.
 
Regards.
 
Matthieu
 

[Juan Luo]

Hello Matthieu,
I will try to reduce the time step and I tell you the resultats later
 
Thanks a lot
Juan