[Nek5000-users] Number of Elements per Characteristic Length for DNS

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

Hi Philipp,

Thank you for getting back to me. Do you have any references that you could
provide so that I can look into this further?

Thanks,

Tommy

On Thu, Jul 12, 2018 at 4:25 AM, <nek5000-users at lists.mcs.anl.gov> wrote:

> Hi,
> typically, in wall bounded turbulence you would design the mesh based on
> inner scaled quantities (i.e. based on the viscous length scale l*). This
> is what we have done in the paper by El Khoury, in accordance to studies in
> channel flow. TOwards the centre, one can then also use Kolmogorov units
> (not sure whether Taylor units are so useful). I am quite convinced that
> the El Khoury simulations are well-resolved DNS, which can also be seen
> when looking at spectra.
>
> Philipp
>
>
> On 2018-07-11 20:58, nek5000-users at lists.mcs.anl.gov wrote:
>
>> Hello All,
>>
>> I am currently investigating the turbulence in a pipe with periodic
>> boundary conditions. I am working on building my mesh and was planning on
>> using Re^(3/4) as the number of elements per characteristic length, but I
>> have found differing methods in literature detailing the number of elements
>> used for DNS. One paper in particular (G.K. El Khoury et al, Direct
>> Numerical Simulation of Turbulent Pipe Flow at Moderately High Reynolds
>> Numbers,  Flow Turbulence Combust, 2013) uses Nek5000 to simulate turbulent
>> flow in a pipe at different Reynolds numbers. The number of elements
>> calculated in this paper seem to be in between the LES and DNS suggested
>> number of elements (element size between the Taylor microscale and the
>> Kolmogorov scale). Turbulent Flows by Pope however suggests a number of
>> elements that is slightly larger than Re^(3/4), and is dependent on the
>> Taylor microscale Reynolds number.
>>
>> Any suggestions on the correct way to determine the number of spectral
>> elements in a characteristic length would be appreciated.
>>
>> Regards,
>>
>> Tommy
>>
>>
>>
>> _______________________________________________
>> Nek5000-users mailing list
>> Nek5000-users at lists.mcs.anl.gov
>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>>
>> _______________________________________________
> Nek5000-users mailing list
> Nek5000-users at lists.mcs.anl.gov
> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/nek5000-users/attachments/20180712/3ca13d06/attachment.html>