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

nek5000-users at lists.mcs.anl.gov nek5000-users at lists.mcs.anl.gov
Thu Jan 5 14:09:08 CST 2017


Hi SL,

Attached is a tar file with an axisymmetric expansion case and a couple of README files.

Please give this a try -- hope this helps you to understand how genbox can do this.

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 12:04 PM
To: nek5000-users at lists.mcs.anl.gov
Subject: Re: [Nek5000-users] problem with 2d axisymmetric       numerical       simulation

Hi Paul,

thank you very much, it works!

However, I am trying to re-define the geometry generated by genbox:
#
Box
-12    -4                nelx,nely,nelz for Box)
-2.0   4.0   1.0        x0 x1 ratio
  0.0   1.0   0.6        y0 y1 ratio
P  ,P  ,A  ,W  ,        bc's

The idea is to generate 3 different squared domains:
              -----------
              |          |
-------- y1
|       |----| y2       |
|
------------------------|
         x1    x2


So, I have included in usrdat2 subroutine:

       do i=1,ntot
          if (xm1(i,1,1,1).lt.x1) then
             ym1(i,1,1,1)=y1
          elseif (xm1(i,1,1,1).ge.x1.and.xm1(i,1,1,1).lt.x2) then
             ym2(i,1,1,1)=y2
          end if
        end do


However, when I run Nek5000 I obtain the following error...

  call usrdat2
  done :: usrdat2

  regenerate geometry data           1


     0  ERROR:  Vanishing Jacobian near      5th node of element
4.
   -2.0182169769993447E-015  0.18749999999999875
     0 xyz:  -1.20930E+00   5.00000E-01
     0 xyz:  -7.90701E-01   6.25000E-01

Is there any different way to create these several domains using genbox?
Thank you
SL



El 03-01-2017 18:26, nek5000-users at lists.mcs.anl.gov escribió:
> Hi SL,
>
> Attached is an axisymmetric example that I've just set up.
>
> Several subdomains are also possible, but you must pay attention
> to the "A  " bc.
>
> Please let me know if the attached works and gives the right answer.
> It looked ok, but I confess I didn't get out a paper and pencil to
> verify
> that the answer is indeed correct....
>
> 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 10:07 AM
> To: nek5000-users at lists.mcs.anl.gov
> Subject: Re: [Nek5000-users] problem with 2d axisymmetric numerical
>  simulation
>
> 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
>>
>> _______________________________________________
>> Nek5000-users mailing list
>> Nek5000-users at lists.mcs.anl.gov
>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>> _______________________________________________
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>> Nek5000-users at lists.mcs.anl.gov
>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>
>
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