<div dir="ltr">Hello Philipp,<div><br></div><div>Thanks again for getting back to me and for sending these references.</div><div><br></div><div>Regards,</div><div><br></div><div>Tommy</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Jul 12, 2018 at 9:07 AM, <span dir="ltr"><<a href="mailto:nek5000-users@lists.mcs.anl.gov" target="_blank">nek5000-users@lists.mcs.anl.gov</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">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:<br>
<br>
<a href="https://aip.scitation.org/doi/abs/10.1063/1.3247176" rel="noreferrer" target="_blank">https://aip.scitation.org/doi/<wbr>abs/10.1063/1.3247176</a><br>
<br>
Philipp<span class=""><br>
<br>
On 2018-07-12 14:56, <a href="mailto:nek5000-users@lists.mcs.anl.gov" target="_blank">nek5000-users@lists.mcs.anl.go<wbr>v</a> wrote:<br>
</span><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">
Hi Philipp,<br>
<br>
Thank you for getting back to me. Do you have any references that you could provide so that I can look into this further?<br>
<br>
Thanks,<br>
<br>
Tommy<br>
<br></span><span class="">
On Thu, Jul 12, 2018 at 4:25 AM, <<a href="mailto:nek5000-users@lists.mcs.anl.gov" target="_blank">nek5000-users@lists.mcs.anl.g<wbr>ov</a> <mailto:<a href="mailto:nek5000-users@lists.mcs.anl.gov" target="_blank">nek5000-users@lists.mc<wbr>s.anl.gov</a>>> wrote:<br>
<br>
Hi,<br>
typically, in wall bounded turbulence you would design the mesh<br>
based on inner scaled quantities (i.e. based on the viscous length<br>
scale l*). This is what we have done in the paper by El Khoury, in<br>
accordance to studies in channel flow. TOwards the centre, one can<br>
then also use Kolmogorov units (not sure whether Taylor units are so<br>
useful). I am quite convinced that the El Khoury simulations are<br>
well-resolved DNS, which can also be seen when looking at spectra.<br>
<br>
Philipp<br>
<br>
<br>
On 2018-07-11 20:58, <a href="mailto:nek5000-users@lists.mcs.anl.gov" target="_blank">nek5000-users@lists.mcs.anl.go<wbr>v</a><br></span><span class="">
<mailto:<a href="mailto:nek5000-users@lists.mcs.anl.gov" target="_blank">nek5000-users@lists.mc<wbr>s.anl.gov</a>> wrote:<br>
<br>
Hello All,<br>
<br>
I am currently investigating the turbulence in a pipe with<br>
periodic boundary conditions. I am working on building my mesh<br>
and was planning on using Re^(3/4) as the number of elements per<br>
characteristic length, but I have found differing methods in<br>
literature detailing the number of elements used for DNS. One<br>
paper in particular (G.K. El Khoury et al, Direct Numerical<br>
Simulation of Turbulent Pipe Flow at Moderately High Reynolds<br>
Numbers, Flow Turbulence Combust, 2013) uses Nek5000 to<br>
simulate turbulent flow in a pipe at different Reynolds numbers.<br>
The number of elements calculated in this paper seem to be in<br>
between the LES and DNS suggested number of elements (element<br>
size between the Taylor microscale and the Kolmogorov scale).<br>
Turbulent Flows by Pope however suggests a number of elements<br>
that is slightly larger than Re^(3/4), and is dependent on the<br>
Taylor microscale Reynolds number.<br>
<br>
Any suggestions on the correct way to determine the number of<br>
spectral elements in a characteristic length would be appreciated.<br>
<br>
Regards,<br>
<br>
Tommy<br>
<br>
<br>
<br>
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