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<p style="margin-top:0;margin-bottom:0">One additional comment ---</p>
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<p style="margin-top:0;margin-bottom:0">I generally find PnPn to do a better job of LES than PnPn-2, presumably because of the better accuracy for pressure.</p>
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<p style="margin-top:0;margin-bottom:0">Also, interestingly, you can look both at integrated tau_wall and at mean dp/dx for the LES. Generally, these are in better agreement for PnPn (based on my past experience...)</p>
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<p style="margin-top:0;margin-bottom:0">If you are running constant flow rate (p54/55 nonzero) then</p>
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<p style="margin-top:0;margin-bottom:0">grep volf logfile > t.t</p>
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<p style="margin-top:0;margin-bottom:0">and plot col 3 of t.t vs col 1 of t.t will show the mean pressure drop, assuming that the body force set in userf is == 0.</p>
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<p style="margin-top:0;margin-bottom:0">I apologize that the volf line does not also show the time, but only the time step number.</p>
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<p style="margin-top:0;margin-bottom:0">(We should correct that...)</p>
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<p style="margin-top:0;margin-bottom:0">Paul</p>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Nek5000-users <nek5000-users-bounces@lists.mcs.anl.gov> on behalf of nek5000-users@lists.mcs.anl.gov <nek5000-users@lists.mcs.anl.gov><br>
<b>Sent:</b> Friday, December 22, 2017 8:59:52 AM<br>
<b>To:</b> nek5000-users@lists.mcs.anl.gov<br>
<b>Subject:</b> Re: [Nek5000-users] Reynolds number setting in the turbChannel example</font>
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<div class="BodyFragment"><font size="2"><span style="font-size:11pt;">
<div class="PlainText">Hi,<br>
the formula mentioned by Paul can be found in Pope's book (Dean's <br>
correlation). Indeed, if Re_tau is off by more than a few percent (say <br>
10) then the quality of the LES is probably not good. Typically, I would <br>
expect a dynamic Smagorinsky model to lead to an underprediction of the <br>
shear.<br>
<br>
Philipp<br>
<br>
On 2017-12-22 15:19, nek5000-users@lists.mcs.anl.gov wrote:<br>
> <br>
> Yes -- but presumably if the LES is at all accurate then the mean wall <br>
> shear should be reasonably close to DNS or it has otherwise missed an <br>
> important quantity of interest?<br>
> <br>
> <br>
> Paul<br>
> <br>
> <br>
> ------------------------------------------------------------------------<br>
> *From:* Nek5000-users <nek5000-users-bounces@lists.mcs.anl.gov> on <br>
> behalf of nek5000-users@lists.mcs.anl.gov <nek5000-users@lists.mcs.anl.gov><br>
> *Sent:* Friday, December 22, 2017 7:40:46 AM<br>
> *To:* nek5000-users@lists.mcs.anl.gov<br>
> *Subject:* Re: [Nek5000-users] Reynolds number setting in the <br>
> turbChannel example<br>
> Re_tau is a simulation result and not known a-priori i.e. the number <br>
> below holds for a DNS but not for an LES.<br>
> <br>
> <br>
> -----Original message-----<br>
>> From:nek5000-users@lists.mcs.anl.gov <nek5000-users@lists.mcs.anl.gov><br>
>> Sent: Friday 22nd December 2017 14:33<br>
>> To: nek5000-users@lists.mcs.anl.gov<br>
>> Subject: Re: [Nek5000-users] Reynolds number setting in the turbChannel example<br>
>> <br>
>> Hi Zhenrong,<br>
>> <br>
>> I used 2800 for shear Reynolds number 180 in channel flow and got a good agreement with Kim et al. (1987).<br>
>> <br>
>> Hope it work to you.<br>
>> <br>
>> <br>
>> _______________________________________________<br>
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