[Nek5000-users] rms fluctuations of passive scalar

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

Hi Zhicheng,

There are some problems w/ overshoot & undershoot of temperature
for passive scalars in under-resolved situations.  I'm not certain,
however, that that's the difficulty you are encountering in your case.

Your early-time results look fine, as you note.   I'm trying to 
recreate the situation here.

Paul



On Thu, 9 Dec 2010, nek5000-users at lists.mcs.anl.gov wrote:

> Hi Neks,
>
> I'm doing LES of heat transfer in a fully turbulent plane channel flow with
> uniform thermal boundary condition. Re_tau=150, Pr=0.7.
> The domain is 6.4/2.0/3.2,  8*8*8 elements using N=8.
>
> When I compare my results with Kasagi's,  it looks like the mean velocity
> and temperature distribution are good. AT dimensionless time 165, the rms
> value of temperature is good, however, as I restart from time 165 to 402,
> the difference between my results and Kasagi's
> became larger and larger.
>
> I'm using standard eddy viscosity model, the same as example turbChannel.
> In case some one had this kind of problem, I attached two figures, one  is
> rms fluctuation at dimensionless time 165, the other is that at 402.
>
> -- 
> Zhicheng Wang
>