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

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

 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
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