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

nek5000-users at lists.mcs.anl.gov nek5000-users at lists.mcs.anl.gov
Tue Jan 3 10:07:06 CST 2017


Dear Paul,

thank you very much for your rapid response.

I have used 'A ' BC in the edge 1, however the problem persists... I am 
wondering if the problem could be in how I have defined my geometry:

Is it necessary to define edge 1 as x \in [0,10]? Because I have defined 
x \in [-2,8]...
Is it possible to generate edge 1 as a combination of several 
subdomains? Because I have divided the geometry in 3 subdomains...

Thank you in advance.
SL

El 03-01-2017 14:38, nek5000-users at lists.mcs.anl.gov escribió:
> 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
> 
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