[Nek5000-users] New Recycling BC method?

Wed Jun 16 21:35:30 CDT 2010

Hi Paul, 

Thanks for the reply.  The reason for the interest is due to the Gambit to Nek matlab code. We have had great success importing complex geometries with it, but now we run into the issue of the recycling boundary condition.  Gambit's ordering of the elements is not always consistent which makes it impossible to use the current technique. 

Our solution was to create the portion that has the recycling in prex and then merge it with the complex part created in Gambit. However, this is proving to be very time consuming and troublesome (Element Mismatch Errors).  So, to avoid this I would like to come up with a new recycling method that does not depend on the elements being in a specific order. My understanding is that the current method looks at the inflow, counts a certain number of elements up, copies this outflow from face 6 and puts it back into the inflow face 5. 

What I would like to do is replace how the inflow plane is connected to the outflow plane. My idea was to use the connectivity matrix to figure out what the element numbers and outflow faces are at a certain distance away from the inflow plane, and use these faces to connect.  The cross-section for the inflow and outflow plane would be the same, but you couldn't necessarily say that it is located, say inflow + 30 elements for example, OR that the outflow and inflow faces are all the same (face 5 for inflow, face 6 for outflow for example).  

Do you think this is possible? In a way, you would be creating a new connectivity matrix that governs the recycling BC. 

Thanks! 

- Michael M. 

----- Original Message ----- 
From: nek5000-users at lists. mcs . anl .gov 
To: nek5000-users at lists. mcs . anl .gov 
Sent: Wednesday, June 16, 2010 9:08:00 PM GMT -06:00 US/Canada Central 
Subject: Re: [Nek5000-users] New Recycling BC method? 

Hi Michael, Access to the connectivity array wouldn't help in this case, given that the recycling bc needs to establish a _new_ connectivity that has nothing to do with the existing one. The examples use this approach of establishing a new connectivity. I'm confident that we can make the existing approach for any mesh that can legitimally employ the recycling bc - i.e., any mesh that has the same cross-sectional distribution of elements at the two planes of interest. An alternative is to use the general purpose interpolation routines. There may (or may not) be a performance issue -- we're looking into this w/ the help of a summer student. Please let me know if I can assist you w/ your specific case. Paul > I am still trying to figure this idea out, but I think I would need to > access the connectivity/boundary condition information that is contained > in the rea file. Does anyone know the array, or what to call in order to > access this in the usr file?  Thanks again for any help! > > > > - Michael M. > > > ----- Original Message ----- > From: nek5000-users at lists. mcs . anl .gov > To: " Nekton User List" > Sent: Tuesday, June 15, 2010 9:02:00 PM GMT -06:00 US/Canada Central > Subject: [Nek5000-users] New Recycling BC method? > > > > > Hello All, > > > > I am wondering if there is another technique to set up a recycling boundary condition that does not depend on the elements being in a certain order (say based on element coordinates for instance)?   I would like to pick the recycling plane based on a given offset distance rather than a number of elements. > > > > Also, the outflow plane faces may not all necessarily be face 6 (and face 5 for the inflow plane). > > > > I have tried going through the examples where a recycling BC is used however I am finding it difficult to understand as my knowledge of Fortan is still growing. Thanks for any help anyone can provide with this idea. > > > > Regards, > > Michael M. > > >   > _______________________________________________ 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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/nek5000-users/attachments/20100616/9053dc0f/attachment.html>