[Nek5000-users] Temperature gradient at a point
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Thu Aug 26 15:30:06 CDT 2010
What's the error message you are getting?
It may be the case, I know that I have had issues with settings and conj HT before since they are (mainly because of our group) revisiting CHT and fixing issues that we request. The latest issue, like I mentioned, was the new time stepping scheme and CHT.
Did the error show up during compiling, or during the run in the output log?
- Mike
----- Original Message -----
From: nek5000-users at lists.mcs.anl.gov
To: nek5000-users at lists.mcs.anl.gov
Sent: Thursday, August 26, 2010 2:18:39 PM GMT -06:00 US/Canada Central
Subject: Re: [Nek5000-users] Temperature gradient at a point
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
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--
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-----------------------------------------------------------------------
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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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