[Nek5000-users] Nek5000-users Digest, Vol 73, Issue 10

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

Not sure whether it helps in your case, but this might in fact be 
related not to 4 vs 8-byte, but rather to interpolation inside Visit. 
Try to not cut exactly at element boundaries, but just a tiny bit away 
from is, so for instance don't put a cut at z=0, but rather at z=0.001. 
This has fixed the problem for us in some situations.

Philipp

On 2015-03-16 19:46, nek5000-users at lists.mcs.anl.gov wrote:
> Hi Philipp,
>
> After changing the setting in 'Control/View', VisIt indeed read in
> the 8-byte output data. However, it seems there are still some
> problems visualising the data. It didn't show the contour plots
> properly when I created some slices. I guess we need to look forward
> to the next version as you mentioned.
>
> Thank you very much for your help.
>
> Best regards, Tony
>
> ________________________________________ From:
> nek5000-users-bounces at lists.mcs.anl.gov
> <nek5000-users-bounces at lists.mcs.anl.gov> on behalf of
> nek5000-users-request at lists.mcs.anl.gov
> <nek5000-users-request at lists.mcs.anl.gov> Sent: 16 March 2015 17:00
> To: nek5000-users at lists.mcs.anl.gov Subject: Nek5000-users Digest,
> Vol 73, Issue 10
>
> Send Nek5000-users mailing list submissions to
> nek5000-users at lists.mcs.anl.gov
>
> To subscribe or unsubscribe via the World Wide Web, visit
> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users or, via
> email, send a message with subject or body 'help' to
> nek5000-users-request at lists.mcs.anl.gov
>
> You can reach the person managing the list at
> nek5000-users-owner at lists.mcs.anl.gov
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Nek5000-users digest..."
>
>
> Today's Topics:
>
> 1. Re: Output data format and VisIt issue
> (nek5000-users at lists.mcs.anl.gov)
>
>
> ----------------------------------------------------------------------
>
>  Message: 1 Date: Sun, 15 Mar 2015 20:50:53 +0100 From:
> nek5000-users at lists.mcs.anl.gov To: nek5000-users at lists.mcs.anl.gov
> Subject: Re: [Nek5000-users] Output data format and VisIt issue
> Message-ID:
> <mailman.3586.1426449067.3643.nek5000-users at lists.mcs.anl.gov>
> Content-Type: text/plain; charset=windows-1252; format=flowed
>
> Hi, indeed, VisIt even in the latest version does not read the 8-byte
> format properly. The problem, in fact, is mainly related to the
> computations of the limits (at least in 2D), and by just setting
> these manually (in Controls/View) it can be corrected. The data
> appears to be read in without problem.
>
> Jing has analysed the source code of the Nek reader, and fixed the
> corresponding parts; he has already sent it further to the VisIt
> developers, and hopefully the next version will read 8-byte files as
> well.
>
> Regarding the restart with 4-byte files, I guess the answer is that
> it depends on the case and the requirements on accuracy you have. In
> my opinion, for stability calculations you will not only need 8-byte
> files, but also the restart from 4 files (aka proper restart).
> Similar observations we have made for high-Reynolds-number
> turbulence. On the other hand, for low-Re cases I guess there is not
> much of a problem.
>
> Best regards, Philipp
>
>
> On 2015-03-15 20:16, nek5000-users at lists.mcs.anl.gov wrote:
>> Dear Neks,
>>
>>
>> Recently I've been playing with VisIt and it seems there is still
>> problem reading nek5000 output data in 8-byte format. VisIt reads
>> 4-byte output data successfully but not 8-byte. Is it essential to
>> output data in 4-byte format if I want to use VisIt (ParaView
>> actually can handle both data format well)?
>>
>>
>> Also, in terms of continuing simulations, would 4-byte precision
>> affect the restarting condition?
>>
>>
>> Hope anyone can help. Thank you very much in advance.
>>
>>
>> Kind regards,
>>
>> Tony
>>
>>
>> _______________________________________________ Nek5000-users
>> mailing list Nek5000-users at lists.mcs.anl.gov
>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>>
>
>
> ------------------------------
>
> _______________________________________________ Nek5000-users mailing
> list Nek5000-users at lists.mcs.anl.gov
> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>
>
> End of Nek5000-users Digest, Vol 73, Issue 10
> *********************************************
> _______________________________________________ Nek5000-users mailing
> list Nek5000-users at lists.mcs.anl.gov
> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>