[Nek5000-users] Average in arbitrary direction

nek5000-users at lists.mcs.anl.gov nek5000-users at lists.mcs.anl.gov
Thu May 19 09:21:03 CDT 2011


Hello Paul,

This sound like exactly what I need.  I didn't find anything like
interp() while using grep in the repo--are you referring to the
routines found in postpro.f ??

Thanks,

Josh

On Wed, May 18, 2011 at 3:59 PM,  <nek5000-users at lists.mcs.anl.gov> wrote:
>
> Hi Josh,
>
> You can use the interp() routines --- let me check if we have
> examples in the repo.
>
> These are somewhat expensive, so if you're also integrating in
> time (even over just 10 steps), it would pay to only interpolate
> the time-averaged data, rather than interpolating every timestep
> and then averaging the profiles.   However, I can understand that
> there are times you'd want the full time signal.
>
> The best integration formulae for periodic signals (e.g., in your theta
> direction and perhaps in z, if you have periodicity)
> is to simply sum the values, sampled uniformly in space (z or
> theta), and dived by n, the number of samples.   You do need
> to sample with sufficient density to capture all the wiggles ---
> another reason that time averaging has value.
>
> Paul
>
>
>
> On Wed, 18 May 2011, nek5000-users at lists.mcs.anl.gov wrote:
>
>> Hello Neks,
>>
>> I have looked at the turbChannel example for an example on planar
>> averaging.
>>
>> However, I was wondering if there was any advice  on how to do this if
>> the elements aren't exactly "nice"... (i.e., the elements may have
>> arbitrary rotations)
>>
>> Specifically, I have a pipe flow, and I am wanting to do an average in
>> the z (axial) direction.  My initial thoughts were to interpolate my
>> values to set R, theta components, and then average this along z.  I'm
>> stuck on the best way to do either one of these operations, however
>> (especially because I would like to use an integration rule to compute
>> the average in the z direction).
>>
>> If anyone could point me in the right direction, that would be a big
>> help.  Thanks!
>>
>> --
>> Josh Camp
>>
>> "All that is necessary for the triumph of evil is that good men do
>> nothing" -- Edmund Burke
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-- 
Josh Camp

"All that is necessary for the triumph of evil is that good men do
nothing" -- Edmund Burke



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