<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: Times New Roman; font-size: 12pt; color: #000000'>What's the error message you are getting? <br><br>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.<br><br>Did the error show up during compiling, or during the run in the output log?<br><br> - Mike<br><br>----- Original Message -----<br>From: nek5000-users@lists.mcs.anl.gov<br>To: nek5000-users@lists.mcs.anl.gov<br>Sent: Thursday, August 26, 2010 2:18:39 PM GMT -06:00 US/Canada Central<br>Subject: Re: [Nek5000-users] Temperature gradient at a point<br><br>Hi,<br><br>Is there any reason why a conjucate heat transfer case should not work with IFLOMACH turned on?<br>I did modify the uservp to set utrans = 1./temp.<br><br>Thanks,<br>Pradeep<br><br>c-----------------------------------------------------------------------<br>
subroutine uservp (ix,iy,iz,ieg)<br> include 'SIZE'<br> include 'TOTAL'<br> include 'NEKUSE'<br><br> if (ifield.eq.1) then<br> utrans = 1./temp<br>c utrans = param(1)<br>
udiff = param(2)<br><br> else<br><br> utrans = 1./temp ! thermal properties<br>c utrans = param(7)<br> udiff = param(8)<br><br> if (ieg .gt. nelgv) then ! properties in the solid<br>
udiff = 0.1*param(8) ! conductivity<br> utrans = 1.0<br> endif<br><br> endif<br><br> return<br> end<br>c-----------------------------------------------------------------------<br>
<br><div class="gmail_quote">
On Mon, Aug 23, 2010 at 4:40 PM, Pradeep Rao <span dir="ltr"><<a href="mailto:stringsofdurga@gmail.com" target="_blank">stringsofdurga@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Thanks Aleks,<br><br>Will give that a try.<div><div></div><div><br><br><div class="gmail_quote">On Mon, Aug 23, 2010 at 4:25 PM, <span dir="ltr"><<a href="mailto:nek5000-users@lists.mcs.anl.gov" target="_blank">nek5000-users@lists.mcs.anl.gov</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">Hi Pradeep,<br>
<br>
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<br>
<br>
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.<br>
<br>
Best,<br>
Aleks<div><div></div><div><br>
<br>
<br>
On Mon, 23 Aug 2010, <a href="mailto:nek5000-users@lists.mcs.anl.gov" target="_blank">nek5000-users@lists.mcs.anl.gov</a> wrote:<br>
<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Hi Paul,<br>
<br>
Thanks for the detailed reply. The reason I'm not solving it as a conjugate<br>
heat transfer problem, is that thermal conductivity is a function of<br>
temperature based on some curve fit equations, and I am not sure how to<br>
implement that.<br>
<br>
Thanks,<br>
Pradeep<br>
<br>
On Mon, Aug 23, 2010 at 4:04 PM, <<a href="mailto:nek5000-users@lists.mcs.anl.gov" target="_blank">nek5000-users@lists.mcs.anl.gov</a>> wrote:<br>
<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<br>
Hi Pradeep,<br>
<br>
Why not just solve the conjugate heat transfer problem directly<br>
using fluid + solid elements in nek?<br>
<br>
Also, nek supports full Robin boundary conditions if you wish<br>
to do a Newton law of cooling: k*dT/dn . n_hat = h*(T-Tinf), where Tinf is<br>
the external temperature and h is the heat transfer coefficient, both of<br>
which can be functions of time and space.<br>
<br>
<br>
Regarding gradm1, you would call it from userchk, and store<br>
the output in arrays in a common block, e.g., as below.<br>
<br>
Paul<br>
<br>
subroutine userchk<br>
:<br>
common /mygrad/ tx(lx1,ly1,lz1,lelt)<br>
$ , ty(lx1,ly1,lz1,lelt)<br>
$ , tz(lx1,ly1,lz1,lelt)<br>
<br>
call gradm1(tx,ty,tz,t)<br>
<br>
:<br>
:<br>
<br>
subroutine userbc (ix,iy,iz,iside,eg)<br>
include 'SIZE'<br>
include 'TOTAL'<br>
include 'NEKUSE'<br>
<br>
common /mygrad/ tx(lx1,ly1,lz1,lelt)<br>
$ , ty(lx1,ly1,lz1,lelt)<br>
$ , tz(lx1,ly1,lz1,lelt)<br>
<br>
integer e,eg<br>
<br>
e = gllel(eg) ! global element number to processor-local el. #<br>
<br>
gtx=tx(ix,iy,iz,e)<br>
gty=ty(ix,iy,iz,e)<br>
gtz=tz(ix,iy,iz,e)<br>
<br>
<br>
<br>
<br>
On Mon, 23 Aug 2010, <a href="mailto:nek5000-users@lists.mcs.anl.gov" target="_blank">nek5000-users@lists.mcs.anl.gov</a> wrote:<br>
<br>
Hi Paul,<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<br>
I am basically trying to solve a conjugate heat transfer problem in an<br>
iterative manner, for flow over an infinitely long cylinder (2D).<br>
<br>
I need to use the heat transfer at the boundary, to calculate the new<br>
temperature at the boundary for the next time step. The<br>
temperature for the next time step is solved for using this heat flux, by<br>
a<br>
function in the usr file using an FEM algorithm for the solid part<br>
(cylinder). The bc type I am using is Temperature - fortran function.<br>
<br>
Regards,<br>
Pradeep<br>
<br>
On Mon, Aug 23, 2010 at 2:50 PM, <<a href="mailto:nek5000-users@lists.mcs.anl.gov" target="_blank">nek5000-users@lists.mcs.anl.gov</a>> wrote:<br>
<br>
<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Pradeep,<br>
<br>
if you give me some idea of the nature of your bc, I can<br>
perhaps help --- there are a large number of bc types already<br>
supported inside nek<br>
<br>
Paul<br>
<br>
<br>
<br>
On Mon, 23 Aug 2010, <a href="mailto:nek5000-users@lists.mcs.anl.gov" target="_blank">nek5000-users@lists.mcs.anl.gov</a> wrote:<br>
<br>
Hi,<br>
<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<br>
I wanted to know if there was a way to find the temperature gradient at<br>
a<br>
point. I need that information in the userbc function.<br>
<br>
I tried using gradm1(), but I am not sure how to get the value at a<br>
given<br>
point.<br>
<br>
Thanks,<br>
Pradeep<br>
<br>
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</blockquote>
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<br>
</blockquote>
<br>
<br>
--<br>
Pradeep C. Rao<br>
Graduate Research Assistant for FT2L (<a href="http://www1.mengr.tamu.edu/FT2L/" target="_blank">http://www1.mengr.tamu.edu/FT2L/</a>)<br>
Department of Mechanical Engineering<br>
Texas A&M University<br>
College Station, TX 77843-3123<br>
<br>
428 Engineering Physics Building<br>
(713) 210-9769<br>
<br>
uuuu<br>
</blockquote>
c-----------------------------------------------------------------------<br>
C<br>
C USER SPECIFIED ROUTINES:<br>
C<br>
C - boundary conditions<br>
C - initial conditions<br>
C - variable properties<br>
C - local acceleration for fluid (a)<br>
C - forcing function for passive scalar (q)<br>
C - general purpose routine for checking errors etc.<br>
C<br>
c-----------------------------------------------------------------------<br>
subroutine uservp (ix,iy,iz,eg)<br>
include 'SIZE'<br>
include 'TOTAL'<br>
include 'NEKUSE'<br>
<br>
integer e,f,eg<br>
c e = gllel(eg)<br>
<br>
udiff =0.<br>
utrans=0.<br>
return<br>
end<br>
c-----------------------------------------------------------------------<br>
subroutine userf (ix,iy,iz,eg)<br>
include 'SIZE'<br>
include 'TOTAL'<br>
include 'NEKUSE'<br>
<br>
integer e,f,eg<br>
c e = gllel(eg)<br>
<br>
<br>
c Note: this is an acceleration term, NOT a force!<br>
c Thus, ffx will subsequently be multiplied by rho(x,t).<br>
<br>
<br>
ffx = 0.0<br>
ffy = 0.0<br>
ffz = 0.0<br>
<br>
return<br>
end<br>
c-----------------------------------------------------------------------<br>
subroutine userq (ix,iy,iz,eg)<br>
include 'SIZE'<br>
include 'TOTAL'<br>
include 'NEKUSE'<br>
<br>
integer e,f,eg<br>
c e = gllel(eg)<br>
<br>
qvol = 0.0<br>
<br>
return<br>
end<br>
c-----------------------------------------------------------------------<br>
subroutine userchk<br>
include 'SIZE'<br>
include 'TOTAL'<br>
return<br>
end<br>
c-----------------------------------------------------------------------<br>
subroutine userbc (ix,iy,iz,iside,ieg)<br>
include 'SIZE'<br>
include 'TOTAL'<br>
include 'NEKUSE'<br>
ux=0.0<br>
uy=0.0<br>
uz=0.0<br>
temp=0.0<br>
return<br>
end<br>
c-----------------------------------------------------------------------<br>
subroutine useric (ix,iy,iz,ieg)<br>
include 'SIZE'<br>
include 'TOTAL'<br>
include 'NEKUSE'<br>
ux=0.0<br>
uy=0.0<br>
uz=0.0<br>
temp=0<br>
return<br>
end<br>
c-----------------------------------------------------------------------<br>
subroutine usrdat<br>
include 'SIZE'<br>
include 'TOTAL'<br>
c<br>
return<br>
end<br>
c-----------------------------------------------------------------------<br>
subroutine usrdat2<br>
include 'SIZE'<br>
include 'TOTAL'<br>
<br>
param(66) = 4. ! These give the std nek binary i/o and are<br>
param(67) = 4. ! good default values<br>
<br>
return<br>
end<br>
c-----------------------------------------------------------------------<br>
subroutine usrdat3<br>
include 'SIZE'<br>
include 'TOTAL'<br>
c<br>
return<br>
end<br>
c-----------------------------------------------------------------------<br>
<br>
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<br>
</blockquote>
<br>
<br>
<br>
-- <br>
Pradeep C. Rao<br>
Graduate Research Assistant for FT2L (<a href="http://www1.mengr.tamu.edu/FT2L/" target="_blank">http://www1.mengr.tamu.edu/FT2L/</a>)<br>
Department of Mechanical Engineering<br>
Texas A&M University<br>
College Station, TX 77843-3123<br>
<br>
428 Engineering Physics Building<br>
(713) 210-9769<br>
<br>
</blockquote>
_______________________________________________<br>
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</div></div></blockquote></div><br><br clear="all"><br></div></div>-- <br><div><div></div><div>Pradeep C. Rao<br>Graduate Research Assistant for FT2L (<a href="http://www1.mengr.tamu.edu/FT2L/" target="_blank">http://www1.mengr.tamu.edu/FT2L/</a>)<br>
Department of Mechanical Engineering<br>
Texas A&M University<br>College Station, TX 77843-3123<br><br>428 Engineering Physics Building<br>(713) 210-9769<br>
</div></div></blockquote></div><br><br clear="all"><br>-- <br>Pradeep C. Rao<br>Graduate Research Assistant for FT2L (<a href="http://www1.mengr.tamu.edu/FT2L/" target="_blank">http://www1.mengr.tamu.edu/FT2L/</a>)<br>Department of Mechanical Engineering<br>
Texas A&M University<br>College Station, TX 77843-3123<br><br>428 Engineering Physics Building<br>(713) 210-9769<br>
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