[Nek5000-users] low order interpolation

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

Hi Tanmoy

I really don't understand why the interpolation fails.. I hope that someone
can help me because a sample low order interpolation could solve my problem.

Thanks anyway
Alessandro

2015-11-21 23:53 GMT+01:00 <nek5000-users at lists.mcs.anl.gov>:

> Hi Alessandro,
>
> Ok. But, I was not talking about your matlab routines, but rather I was
> talking about your nek5000 postprocessing mode. I guess they are correct,
> since you got good results with Tecplot.
>
> But anyway, the bottom line is, nek5000 uses spectral interpolation
> routine, so even the higher order polynomials are orthogonal, so it is
> unlikely that you will have Runge's phenomenon.
>
> Also, I myself use hpts routines for interpolating a turbulent field
>
> Best Regards,
> Tanmoy
>
> On Fri, Nov 20, 2015 at 10:41 AM, <nek5000-users at lists.mcs.anl.gov> wrote:
>
>> Hi Tanmoy
>>
>> thanks for the quick answer, unfortunately I didn't commit this kinds of
>> errors. I have already used my matlab routine for other cases and it worked
>> well, so I'm pretty sure that there isn't errors. The only differences is
>> that I'm using this routine to interpolate the hpts.in points on more
>> complex grid and on a turbulent field. It seams that I have the Runge's
>> phenomenon. Is this possible with the hpts routine?
>>
>> Sincerely
>> Alessandro
>>
>>
>>
>>
>>
>> 2015-11-20 17:29 GMT+01:00 <nek5000-users at lists.mcs.anl.gov>:
>>
>>> Hi Alessandro,
>>>
>>> I use exactly the same procedure for my case. Just wondering, by any
>>> chance, are there any points in hpts.in which are outside bounds of the
>>> original domain, or you may resize the domain in userdat(), while
>>> postprocessing in nek5000.
>>>
>>> Best Regards,
>>> Tanmoy
>>>
>>> On Fri, Nov 20, 2015 at 6:46 AM, <nek5000-users at lists.mcs.anl.gov>
>>> wrote:
>>>
>>>> Dear neks
>>>>
>>>> I don't know how Nek5000 performs the interpolation with hpts() routine
>>>> but I have some problem when I use this last. Using Matlab I built an
>>>> hpts.in file that contains the points of a structured and not constant
>>>> mesh, then using Nek in postprocessing  mode I evaluate the values of
>>>> velocity an pressure in this points. When I reshape the hpts.out in order
>>>> to visualize my domain, there are many zones that have no-sense values!. I
>>>> performed the same interpolation in tecplot and it works fine.
>>>>
>>>> my question is: there's any way to perform a first order interpolation
>>>> in Nek5000?
>>>>
>>>> Sincerely
>>>> Alessandro
>>>>
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