[Nek5000-users] turbulent heat transfer

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

Hi Alex,

I see you have ifadv set to T, which is correct.

However, I also see that your conductivity is -.7, which
implies your Peclet number is 0.7 ---- (assuming your 
Reynolds number is 750).  Is this what you want ?

Also, are you using periodic boundary conditions?
If so, it takes a bit of care to get meaningful
forcing conditions, particularly for the fixed-temperature
boundary condition.  (This condition leads to determination
of an eigenvalue to find the fully-developed flow conditions,
which have a bulk temperature scaling like  exp(-lambda x).
I can point you to some techniques for developing such 
conditions if you'd like.)

Paul



On Wed, 13 Feb 2013, nek5000-users at lists.mcs.anl.gov wrote:

> Dear all
>
> we are trying to make calculations of turbulent heat transfer in a
> pipe. Everything seems to work fine
> with the velocity field, however this is not the case for the
> temperature. It seems as if the convection
> for the temperature equation is switched off. So, we obtain a
> turbulent velocity distribution but a laminar temperature
> distribution.
>
> We have tried several thermal boundary condtions and at the moment we
> are just fixing the temperature at the wall
> T=0 and adding a heat source qvol=1. In the following we add details
> of the case.
>
> Thanks for your help
>
> Regards,
> Alex
>
> rea file
> ****** PARAMETERS *****
>   2.6099999      NEKTON VERSION
>   3 DIMENSIONAL RUN
>         103  PARAMETERS FOLLOW
>   1.00000     p001 DENSITY
>  -750.       p002 VISCOS
>   0.00000     p003
>   0.00000     p004
>   0.00000     p005
>   0.00000     p006
>   1.00000     p007 RHOCP
>  -0.7         p008 CONDUCT
> [...]
>          13   LOGICAL SWITCHES FOLLOW
> T      IFFLOW
> T      IFHEAT
> T      IFTRAN
> T T F F F F F F F F F IFNAV & IFADVC (convection in P.S. fields)
> F F T T T T T T T T T T  IFTMSH (IF mesh for this field is T mesh)
> F      IFAXIS
> F      IFSTRS
> F      IFSPLIT
> F      IFMGRID
> F      IFMODEL
> F      IFKEPS
> F      IFMVBD
> F      IFCHAR
> [...]
>
> usr file
> [...]
> c-----------------------------
> ------------------------------------------
>      subroutine userf  (ix,iy,iz,ieg)
>      include 'SIZE'
>      include 'TOTAL'
>      include 'NEKUSE'
>
>      ffx = 0.0
>      ffy = 0.0
>      ffz = 2.0
>
>      return
>      end
> c-----------------------------------------------------------------------
>      subroutine userq  (ix,iy,iz,ieg)
>      include 'SIZE'
>      include 'TOTAL'
>      include 'NEKUSE'
>
>      qvol   = 1.0
>      source = 0.0
>
>      return
>      end
> c-----------------------------------------------------------------------
> [...]
>