[Nek5000-users] Temperature gradient at a point
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Thu Aug 26 14:18:39 CDT 2010
Hi,
Is there any reason why a conjucate heat transfer case should not work with
IFLOMACH turned on?
I did modify the uservp to set utrans = 1./temp.
Thanks,
Pradeep
c-----------------------------------------------------------------------
subroutine uservp (ix,iy,iz,ieg)
include 'SIZE'
include 'TOTAL'
include 'NEKUSE'
if (ifield.eq.1) then
utrans = 1./temp
c utrans = param(1)
udiff = param(2)
else
utrans = 1./temp ! thermal properties
c utrans = param(7)
udiff = param(8)
if (ieg .gt. nelgv) then ! properties in the solid
udiff = 0.1*param(8) ! conductivity
utrans = 1.0
endif
endif
return
end
c-----------------------------------------------------------------------
On Mon, Aug 23, 2010 at 4:40 PM, Pradeep Rao <stringsofdurga at gmail.com>wrote:
> Thanks Aleks,
>
> Will give that a try.
>
>
> On Mon, Aug 23, 2010 at 4:25 PM, <nek5000-users at lists.mcs.anl.gov> wrote:
>
>> Hi Pradeep,
>>
>> Dependence of conductivity on time and space is not a problem once one
>> uses non zero p30 in .rea that activates a call to uservp of .usr file
>>
>> If you also need a dependence of conductivity on temperature you may want
>> to consider either using the values from the previous time step or doing
>> extrapolation in time.
>>
>> Best,
>> Aleks
>>
>>
>>
>> On Mon, 23 Aug 2010, nek5000-users at lists.mcs.anl.gov wrote:
>>
>> Hi Paul,
>>>
>>> Thanks for the detailed reply. The reason I'm not solving it as a
>>> conjugate
>>> heat transfer problem, is that thermal conductivity is a function of
>>> temperature based on some curve fit equations, and I am not sure how to
>>> implement that.
>>>
>>> Thanks,
>>> Pradeep
>>>
>>> On Mon, Aug 23, 2010 at 4:04 PM, <nek5000-users at lists.mcs.anl.gov>
>>> wrote:
>>>
>>>
>>>> Hi Pradeep,
>>>>
>>>> Why not just solve the conjugate heat transfer problem directly
>>>> using fluid + solid elements in nek?
>>>>
>>>> Also, nek supports full Robin boundary conditions if you wish
>>>> to do a Newton law of cooling: k*dT/dn . n_hat = h*(T-Tinf), where Tinf
>>>> is
>>>> the external temperature and h is the heat transfer coefficient, both of
>>>> which can be functions of time and space.
>>>>
>>>>
>>>> Regarding gradm1, you would call it from userchk, and store
>>>> the output in arrays in a common block, e.g., as below.
>>>>
>>>> Paul
>>>>
>>>> subroutine userchk
>>>> :
>>>> common /mygrad/ tx(lx1,ly1,lz1,lelt)
>>>> $ , ty(lx1,ly1,lz1,lelt)
>>>> $ , tz(lx1,ly1,lz1,lelt)
>>>>
>>>> call gradm1(tx,ty,tz,t)
>>>>
>>>> :
>>>> :
>>>>
>>>> subroutine userbc (ix,iy,iz,iside,eg)
>>>> include 'SIZE'
>>>> include 'TOTAL'
>>>> include 'NEKUSE'
>>>>
>>>> common /mygrad/ tx(lx1,ly1,lz1,lelt)
>>>> $ , ty(lx1,ly1,lz1,lelt)
>>>> $ , tz(lx1,ly1,lz1,lelt)
>>>>
>>>> integer e,eg
>>>>
>>>> e = gllel(eg) ! global element number to processor-local el. #
>>>>
>>>> gtx=tx(ix,iy,iz,e)
>>>> gty=ty(ix,iy,iz,e)
>>>> gtz=tz(ix,iy,iz,e)
>>>>
>>>>
>>>>
>>>>
>>>> On Mon, 23 Aug 2010, nek5000-users at lists.mcs.anl.gov wrote:
>>>>
>>>> Hi Paul,
>>>>
>>>>>
>>>>> I am basically trying to solve a conjugate heat transfer problem in an
>>>>> iterative manner, for flow over an infinitely long cylinder (2D).
>>>>>
>>>>> I need to use the heat transfer at the boundary, to calculate the new
>>>>> temperature at the boundary for the next time step. The
>>>>> temperature for the next time step is solved for using this heat flux,
>>>>> by
>>>>> a
>>>>> function in the usr file using an FEM algorithm for the solid part
>>>>> (cylinder). The bc type I am using is Temperature - fortran function.
>>>>>
>>>>> Regards,
>>>>> Pradeep
>>>>>
>>>>> On Mon, Aug 23, 2010 at 2:50 PM, <nek5000-users at lists.mcs.anl.gov>
>>>>> wrote:
>>>>>
>>>>>
>>>>> Pradeep,
>>>>>>
>>>>>> if you give me some idea of the nature of your bc, I can
>>>>>> perhaps help --- there are a large number of bc types already
>>>>>> supported inside nek
>>>>>>
>>>>>> Paul
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Mon, 23 Aug 2010, nek5000-users at lists.mcs.anl.gov wrote:
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>>
>>>>>>> I wanted to know if there was a way to find the temperature gradient
>>>>>>> at
>>>>>>> a
>>>>>>> point. I need that information in the userbc function.
>>>>>>>
>>>>>>> I tried using gradm1(), but I am not sure how to get the value at a
>>>>>>> given
>>>>>>> point.
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Pradeep
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>>
>>>>>>> Nek5000-users mailing list
>>>>>> Nek5000-users at lists.mcs.anl.gov
>>>>>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>> --
>>>>> Pradeep C. Rao
>>>>> Graduate Research Assistant for FT2L (http://www1.mengr.tamu.edu/FT2L/
>>>>> )
>>>>> Department of Mechanical Engineering
>>>>> Texas A&M University
>>>>> College Station, TX 77843-3123
>>>>>
>>>>> 428 Engineering Physics Building
>>>>> (713) 210-9769
>>>>>
>>>>> uuuu
>>>>>
>>>> c-----------------------------------------------------------------------
>>>> C
>>>> C USER SPECIFIED ROUTINES:
>>>> C
>>>> C - boundary conditions
>>>> C - initial conditions
>>>> C - variable properties
>>>> C - local acceleration for fluid (a)
>>>> C - forcing function for passive scalar (q)
>>>> C - general purpose routine for checking errors etc.
>>>> C
>>>> c-----------------------------------------------------------------------
>>>> subroutine uservp (ix,iy,iz,eg)
>>>> include 'SIZE'
>>>> include 'TOTAL'
>>>> include 'NEKUSE'
>>>>
>>>> integer e,f,eg
>>>> c e = gllel(eg)
>>>>
>>>> udiff =0.
>>>> utrans=0.
>>>> return
>>>> end
>>>> c-----------------------------------------------------------------------
>>>> subroutine userf (ix,iy,iz,eg)
>>>> include 'SIZE'
>>>> include 'TOTAL'
>>>> include 'NEKUSE'
>>>>
>>>> integer e,f,eg
>>>> c e = gllel(eg)
>>>>
>>>>
>>>> c Note: this is an acceleration term, NOT a force!
>>>> c Thus, ffx will subsequently be multiplied by rho(x,t).
>>>>
>>>>
>>>> ffx = 0.0
>>>> ffy = 0.0
>>>> ffz = 0.0
>>>>
>>>> return
>>>> end
>>>> c-----------------------------------------------------------------------
>>>> subroutine userq (ix,iy,iz,eg)
>>>> include 'SIZE'
>>>> include 'TOTAL'
>>>> include 'NEKUSE'
>>>>
>>>> integer e,f,eg
>>>> c e = gllel(eg)
>>>>
>>>> qvol = 0.0
>>>>
>>>> return
>>>> end
>>>> c-----------------------------------------------------------------------
>>>> subroutine userchk
>>>> include 'SIZE'
>>>> include 'TOTAL'
>>>> return
>>>> end
>>>> c-----------------------------------------------------------------------
>>>> subroutine userbc (ix,iy,iz,iside,ieg)
>>>> include 'SIZE'
>>>> include 'TOTAL'
>>>> include 'NEKUSE'
>>>> ux=0.0
>>>> uy=0.0
>>>> uz=0.0
>>>> temp=0.0
>>>> return
>>>> end
>>>> c-----------------------------------------------------------------------
>>>> subroutine useric (ix,iy,iz,ieg)
>>>> include 'SIZE'
>>>> include 'TOTAL'
>>>> include 'NEKUSE'
>>>> ux=0.0
>>>> uy=0.0
>>>> uz=0.0
>>>> temp=0
>>>> return
>>>> end
>>>> c-----------------------------------------------------------------------
>>>> subroutine usrdat
>>>> include 'SIZE'
>>>> include 'TOTAL'
>>>> c
>>>> return
>>>> end
>>>> c-----------------------------------------------------------------------
>>>> subroutine usrdat2
>>>> include 'SIZE'
>>>> include 'TOTAL'
>>>>
>>>> param(66) = 4. ! These give the std nek binary i/o and are
>>>> param(67) = 4. ! good default values
>>>>
>>>> return
>>>> end
>>>> c-----------------------------------------------------------------------
>>>> subroutine usrdat3
>>>> include 'SIZE'
>>>> include 'TOTAL'
>>>> c
>>>> return
>>>> end
>>>> c-----------------------------------------------------------------------
>>>>
>>>> _______________________________________________
>>>> Nek5000-users mailing list
>>>> Nek5000-users at lists.mcs.anl.gov
>>>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>>>>
>>>>
>>>
>>>
>>> --
>>> Pradeep C. Rao
>>> Graduate Research Assistant for FT2L (http://www1.mengr.tamu.edu/FT2L/)
>>> Department of Mechanical Engineering
>>> Texas A&M University
>>> College Station, TX 77843-3123
>>>
>>> 428 Engineering Physics Building
>>> (713) 210-9769
>>>
>>> _______________________________________________
>> Nek5000-users mailing list
>> Nek5000-users at lists.mcs.anl.gov
>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>>
>
>
>
> --
> Pradeep C. Rao
> Graduate Research Assistant for FT2L (http://www1.mengr.tamu.edu/FT2L/)
> Department of Mechanical Engineering
> Texas A&M University
> College Station, TX 77843-3123
>
> 428 Engineering Physics Building
> (713) 210-9769
>
--
Pradeep C. Rao
Graduate Research Assistant for FT2L (http://www1.mengr.tamu.edu/FT2L/)
Department of Mechanical Engineering
Texas A&M University
College Station, TX 77843-3123
428 Engineering Physics Building
(713) 210-9769
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