[Nek5000-users] problem with 2d axisymmetric numerical simulation

Tue Jan 3 07:38:41 CST 2017

Dear SL,

For axisymmetric, if the domain contains the axis, then only points along Edge 1
are allowed to be on the axis.  That means that the reference domain, shown
here in the preprocessor notation,

                 3
       +-------------+
       |                  |
  4   |                  |  2
       |                  |
       +-------------+
                 1

must have Edge 1 on the axis and that the BC for edge 1 must be "A  "

If you generate your domain with genbox, this is easily accomplished with something like
the following in a case.box file:

your.rea
2                      spatial dimension
-1                     number of fields
#
#    comments
#
#
#========================================================
#
Box
-6  -4                          nelx,nely,nelz for Box)
0 6      1.0                  x0 x1 ratio
0 1      0.7                  y0 y1 ratio
P  ,P  ,A  ,f  ,              bc's

hth,

Paul

________________________________________
From: nek5000-users-bounces at lists.mcs.anl.gov [nek5000-users-bounces at lists.mcs.anl.gov] on behalf of nek5000-users at lists.mcs.anl.gov [nek5000-users at lists.mcs.anl.gov]
Sent: Tuesday, January 03, 2017 7:12 AM
To: Nek5000 Users
Subject: [Nek5000-users] problem with 2d axisymmetric numerical simulation

Hi Neks,

I am trying to simulate a circular pipe. To start with, I am trying to
perform the 2d axisymmetric simulation. I have generated my mesh using
gmsh, and then converted it to nek5000 format. The 2d numerical
simulation is properly working, however, I am finding some troubles with
the axisymmetric simulation.

When I try to run my simulation, I find the following message, and the
code stop running:
  read .rea file
  nelgt/nelgv/lelt:        1192        1192         200
  lx1  /lx2  /lx3 :           6           4           4

  mapping elements to processors
            0         149         149        1192        1192  NELV
            1         149         149        1192        1192  NELV
            2         149         149        1192        1192  NELV
            3         149         149        1192        1192  NELV
            4         149         149        1192        1192  NELV
            5         149         149        1192        1192  NELV
            6         149         149        1192        1192  NELV
            7         149         149        1192        1192  NELV
  RANK     0 IEG     474     475     476     477     478     479     480
    481
                     482     483     484     485     486     487     488
    489
                     490     492     493     494     495     496     497
    498
                     499     500     501     502     503     504     505
    506
                     507     508     510     511     512     513     514
    515
                     516     517     518     519     520     521     522
    523
                     524     525     526     528     529     530     531
    532
                     533     534     535     536     537     538     539
    540
                     541     542     543     544     546     547     548
    549
                     550     551     552     553     554     555     556
    557
                     558     559     560     561     562     565     566
    567
                     568     569     570     571     572     573     574
    575
                     576     577     578     579     580     583     584
    585
                     586     587     588     589     590     591     592
    593
                     594     595     596     597     598     602     603
    604
                     605     606     607     608     609     610     611
    612
                     620     621     622     623     624     625     626
    627
                     628     639     640     641     642     643     644
    657
                     658     659     660     676     677
  element load imbalance:            0         149         149
  done :: mapping elements to processors

            0  objects found
  done :: read .rea file   0.25710E-01 sec

  setup mesh topology
   Element face on the axis of symmetry must be FACE 1
   Element           6    face           2   is on the axis.
   Element face on the axis of symmetry must be FACE 1
   Element           1    face           2   is on the axis.
   Element face on the axis of symmetry must be FACE 1
   Element           1    face           3   is on the axis.
    Right-handed check complete for    1192 elements. OK.
   Element face on the axis of symmetry must be FACE 1
   Element           2    face           2   is on the axis.
   Element face on the axis of symmetry must be FACE 1
   Element           1    face           2   is on the axis.

Following this post:
http://lists.mcs.anl.gov/pipermail/nek5000-users/2012-August/001906.html

1) I have set
T     IFAXIS
T     IFAZIV
2) I have set 'A ' BC in the region of y=0.
3) I have copied the FLUID BC to the region of THERMAL BOUNDARY
CONDITIONS, modifying
W, v and O by t
4) In the .usr file I have defined:
c-----------------------------------------------------------------------
>     subroutine userf  (ix,iy,iz,eg)
>     include 'SIZE'
>     include 'TOTAL'
>     include 'NEKUSE'
>     integer e,f,eg
>     if(y.gt.0) ffy = temp*temp/y
>     return
>     end
> c-----------------------------------------------------------------------
>     subroutine userq  (ix,iy,iz,eg)
>     include 'SIZE'
>     include 'TOTAL'
>     include 'NEKUSE'
>     integer e,f,eg
>     if(y.gt.0) then
>       visc = param(2)
>       qvol = -uy*temp/y
>     endif
>     return
>     end
> c-----------------------------------------------------------------------
>     subroutine useric (ix,iy,iz,ieg)
>     include 'SIZE'
>     include 'TOTAL'
>     include 'NEKUSE'
>     temp = y
>     return
>     end
> c-----------------------------------------------------------------------
>

Please, could you give me a piece of advise with this numerical
simulation?

Thank you very much in advance.

SL

_______________________________________________
Nek5000-users mailing list
Nek5000-users at lists.mcs.anl.gov
https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users