[Nek5000-users] Nonzero swirl velocity at the centerline

[nek5000-users at lists.mcs.anl.gov]

I have just done that.
Thank you very much.

Outi

6 Oct 2012 kl. 23:56 skrev nek5000-users at lists.mcs.anl.gov:

>
> Thanks... would you mind sending a gzip'd tarfile with
>
> SIZE
> box file
> rea file
> usr file
>
> to me offline?
>
> Best regards,
>
> Paul
>
>
> On Sat, 6 Oct 2012, nek5000-users at lists.mcs.anl.gov wrote:
>
>> Dear Paul,
>>
>> Thank you for the suggestion, but the prescribed profile is just an  
>> inlet profile, and I do get a correct profile at the inlet.
>> The nonzero swirl velocity at the centerline appears downstream.
>>
>> Outi
>>
>> 6 Oct 2012 kl. 23:42 skrev nek5000-users at lists.mcs.anl.gov:
>>
>>> Dear Outi,
>>> If you are prescribing your u_theta (i.e., as temperature),
>>> then from your formula below it should be zero on the axis.
>>> One thing that might be of value (for small problems) is
>>> to add to userbc the statements below
>>>
>>>     if (ifield.eq.2) write(6,1) x,y,temp
>>>   1 format(1p3e13.5,' uxyz')
>>>     if (istep.eq.2) stop
>>> You can then grep uxyz logfile and look at what is going on.
>>> You should see that, for y=0, you match your desired profile.
>>> Paul
>>> On Sat, 6 Oct 2012, nek5000-users at lists.mcs.anl.gov wrote:
>>>> Dear Paul,
>>>> I use the "A  " BC.
>>>> And the new mesh generated by genbox.
>>>> Outi
>>>> 6 Oct 2012 kl. 23:28 skrev nek5000-users at lists.mcs.anl.gov:
>>>>> Dear Outi,
>>>>> Do you have the "A  " bc on your elements that touch the  
>>>>> centerline?
>>>>> Are you using the same mesh as vortex2? Or a new one generated  
>>>>> with
>>>>> genbox.
>>>>> In principal, the A bc should set U_theta=0 on the axis.
>>>>> Paul
>>>>> On Sat, 6 Oct 2012, nek5000-users at lists.mcs.anl.gov wrote:
>>>>>> Dear Neks,
>>>>>> I have started to use the 2D axisymmetric version of Nek5000  
>>>>>> with swirl (like the example vortex2), to get some base flows  
>>>>>> in axisymmetric geometries.
>>>>>> To test the code I modified the vortex2 example to simple  
>>>>>> Grabowski vortex flow.
>>>>>> This means setting the inlet profile:
>>>>>> U_x=1
>>>>>> U_r=0
>>>>>> U_theta=0.8944r(2-r^2)
>>>>>> The result looked good at the first sight, but a closer  
>>>>>> inspection revealed that the swirl velocity (U_theta) is  
>>>>>> nonzero at the centerline (up to U_theta=0.1). Also other  
>>>>>> axisymmetric flow cases with swirl gave nonzero swirl velocities.
>>>>>> I wonder if it would be possible for someone to look into why  
>>>>>> this happens? I have attached the .usr, .rea and .box files  
>>>>>> below.
>>>>>> Also, it would be useful if you could guide me into the precise  
>>>>>> place in the code where the centerline condition for swirl is  
>>>>>> set. Does OMASK have something to do with this? Or is it TMASK?
>>>>>> Outi
>>>>> _______________________________________________
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