[Nek5000-users] Balancing heat flux BCs in periodic domain

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

P.S.

The write line should be:

if (nio.eq.0) write (6,*) ‘tave=‘, tave

Sorry about that

> On Mar 15, 2018, at 12:47, nek5000-users at lists.mcs.anl.gov wrote:
> 
> Hi Jon,
> 
> You can manually force the average temperature to be a certain value. If you add the following code in userchk, the average temperature should be constant:
> 
>      include 'TOTAL'
> 
>      real tw(lx1*ly1*lz1*lelt)
> 
>      offset = 1. ! desired average value
> 
>      n = lx1*ly1*lz1*nelt
> 
>      call col3(tw,t,bm1,n)
>      tave = glsum(tw,n) / voltm1
> 
>      call cadd(t,offset-tave,n)
> 
> If you just want to check the average temperature value, you can add the following lines:
> 
>      call col3(tw,t,bm1,n)
>      tave = glsum(tw,n) / voltm1
>      write (6,*) 'tave=', tave
> 
> Kento
> 
>> On Mar 14, 2018, at 20:46, nek5000-users at lists.mcs.anl.gov wrote:
>> 
>> Hello Nek Users,
>> 
>> I have a periodic fluid domain with heat flux BCs at my walls. To prevent my temperatures from increasing indefinitely, I am prescribing a sink within userq using qvol which is equal to "user_flux * wall_surface_area / fluid_volume".
>> 
>> This works in theory. The issue is that due to round-off errors, my temperatures still increases (although extremely slowly).
>> 
>> I would like my average temperature be the same regardless of run time. What would be the most efficient method to balance the temperature in my domain?
>> 
>> Best,
>> Jon
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>> Nek5000-users at lists.mcs.anl.gov
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> 
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