[Nek5000-users] Connectivety

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

Antonois:

I understand your confusion. Let me backup a little bit.

Genmap will try to establish a unique global numbering for all element vertices. Basically, genmap tries to detect (based on the vertex coordinates) the shared vertices and will assign a global id. We compute what you call the connectivity information on the fly (during the setup phase of Nek) based on the global vertex ids read from the .map file. 

You're right the old ASCII .rea file contains the elemental connectivity but this information is no longer used (we do a formatted dummy read for these lines). The .re2 file does not contain this information anymore.


hth,
Stefan


----- Original Message -----
From: nek5000-users at lists.mcs.anl.gov
To: nek5000-users at lists.mcs.anl.gov
Sent: Friday, December 10, 2010 10:10:16 AM
Subject: Re: [Nek5000-users] Connectivety

Thank you for the responses.
However maybe my question I was clear before. I try again: Ok, the
connectivity information comes from the rea file when you run genmap,
but is it computed based on the spatial coordinates given in the rea
file, or is it just taken from the connectivity information given later,
also in the rea file along with the boundary conditions?

What we experience is that we have a grid which is created in Matlab and
then we write it in "rea file format" which is later read by genmap and
reatore2 etc. This rea file, after the spatial coordinates of the
element corners, contains a list with all the elements and their
connectivity information.
Here is what two lines looks like:

W 4 1  0.000000      0.000000      0.000000      0.000000      0.000000
E 4 2  5.000000      4.000000      0.000000      0.000000      0.000000

Here I specify Wall condition for element 4 and face 1 and Element
condition for face 2 that connects to element 5 with face 4.
But then when I removed my connectivity info, that is having every where
 zeros in the 4th and 5th column:

W 4 1  0.000000      0.000000      0.000000      0.000000      0.000000
E 4 2  0.000000      0.000000      0.000000      0.000000      0.000000

the case seemed to run fine, and the flow looked correct.
Does this mean that the connectivity specified there does not matter?

Best,
/Antonios



nek5000-users at lists.mcs.anl.gov wrote:
> This is correct.
> -Stefan
> 
> ----- Original Message -----
> From: nek5000-users at lists.mcs.anl.gov
> To: nek5000-users at lists.mcs.anl.gov
> Sent: Thursday, December 9, 2010 6:15:02 PM
> Subject: Re: [Nek5000-users] Connectivety
> 
> Hi Antonios,
> 
> I could be wrong but I think that the only connectivity information that 
> Nek5000 need comes from global vertexi element numbering genereated by 
> .map file which is in turn produced by running genmap on .rea file
> 
> Best,
> Aleks
> 
> 
> On Thu, 9 Dec 2010, nek5000-users at lists.mcs.anl.gov wrote:
> 
>> Hello Paul,
>> I have a question about the connectivity of the elements.
>> In the old rea file format (which we convert to the new binary with
>> reatore2) we have listed the Element geometrical date and after that the
>> Boundary conditions and connectivity data.
>> My question is whether the connectivity of the elements stated there is
>> actually used or it is somehow re-computed while the code runs based on
>> the node coordinates. I am talking specifically about the connectivity
>> between the elements, not the boundary conditions with the "outside world".
>> Best regards,
>> Antonios
>>
>> -- 
>> ---------------------------------------------------------------------------------------------
>> Antonios Monokrousos
>> Department of Mechanics                 email:    antonios at mech.kth.se
>> Royal Institute of Technology (KTH)     phone:    +46 8 790 68 76
>> Osquars Backe 18                        telefax:  +46 8 796 98 50
>> SE-100 44 Stockholm, SWEDEN
>> _______________________________________________
>> Nek5000-users mailing list 
>> Nek5000-users at lists.mcs.anl.gov
>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
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-- 
---------------------------------------------------------------------------------------------
Antonios Monokrousos
Department of Mechanics                 email:    antonios at mech.kth.se
Royal Institute of Technology (KTH)     phone:    +46 8 790 68 76
Osquars Backe 18                        telefax:  +46 8 796 98 50
SE-100 44 Stockholm, SWEDEN
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