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

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

I guess the El Khoury paper might be a good starting point; we really 
tried to make sure that the resolution is sufficient for good DNS. 
Otherwise, there is a resolution discussion for spectral methods in the 
paper by Coleman, Johnstone and Spalart:

https://aip.scitation.org/doi/abs/10.1063/1.3247176

Philipp

On 2018-07-12 14:56, nek5000-users at lists.mcs.anl.gov wrote:
> 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 
> <mailto: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
>     <mailto: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
>         <mailto:Nek5000-users at lists.mcs.anl.gov>
>         https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>         <https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users>
> 
>     _______________________________________________
>     Nek5000-users mailing list
>     Nek5000-users at lists.mcs.anl.gov <mailto:Nek5000-users at lists.mcs.anl.gov>
>     https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>     <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
>