[Nek5000-users] New Recycling BC based on interpolation

Fri Jul 16 17:47:28 CDT 2010

Hi Paul, 

Thanks for the emails. At present, it seems easier and more straight forward to use a discriminator for RBC so long as it doesn't effect any other routine (like you mentioned other routines that use 'v '). I think, but could be wrong, that the recycling routine negates using the 'v ' boundary condition for that particular inlet? 

I think that as long as the discriminator change doesn't effect anything and at the same time, not calling it 'v ' doesn't cause any issues that the discriminator would be easier. 

In the mean time I can try creating the bc() based on cbc and geometry location and use that. 

- Michael 

----- Original Message ----- 
From: nek5000-users at lists.mcs.anl.gov 
To: nek5000-users at lists.mcs.anl.gov 
Sent: Friday, July 16, 2010 5:32:17 PM GMT -06:00 US/Canada Central 
Subject: Re: [Nek5000-users] New Recycling BC based on interpolation 

Hi Michael, 

As a follow-up --- if you need me to code up a more sophisticated 
discriminator, I'm happy to do so. 

Paul 

On Fri, 16 Jul 2010, nek5000-users at lists.mcs.anl.gov wrote: 

> 
> 
> Hi Michael, 
> 
> Thanks for the suggestion --- I think it's a good one, but we're 
> not quite there yet. I have a couple of comments - 
> 
> Technically "R " is the same as "v " --- because it is a time-space 
> varying prescribed Dirichlet condition. 
> 
> Why not simply populate bc(4,f,e,1) with 1,2,3,... to indicate that it is a 
> Recycle bc of type 1,2,3,... ? For every cbc, there 
> are 6 bc() entries (i.e, bc(k,f,e,1) for k=1 to 6). For "v ", the first one 
> of these (k=1) is reserved. 
> 
> That being said, genmap doesn't care about any bc other than "O " and 
> "P " (in fact, only "P " at this point), so you could in fact do what 
> you propose right now, as long as you replace in usrdat or usrdat2 with 
> the functionally correct "v " bc. 
> 
> At present I'm a bit reluctant to make a change to the repo that is 
> still in flux w.r.t. development -- There are a few issues to resolve. 
> Presumably what one wants to be able to specify is the translation 
> distance -- with respect to what? -- and the scale factor as a function 
> of time. We have selected w.r.t. to the unit normal on the R face. In 
> exact arithmetic there's no difficulty - but in some tricky situations 
> there will be problems. Rather than try to engineer a solution for all 
> possible scenarios I think it's best to handle this on a case-by-case 
> basis until we get a handle on what works and what doesn't. 
> 
> There are also performance issues to be investigated, particularly at 
> high processor counts. 
> 
> In a few months I expect we'll have a consolidated code team such 
> that we can implement changes (at least the mechanics of them) 
> without much difficulty. Right now (through the summer) we're 
> a bit saturated. 
> 
> Paul 
> 
> 
> On Fri, 16 Jul 2010, nek5000-users at lists.mcs.anl.gov wrote: 
> 
>> Oh ok. 
>> 
>> Let's say that I leave one inlet as 'v ', but then change the other 
>> inlet to some other variable 'v1 ' or 'X ' or whatever. Would this be 
>> ok, without interfering with other routines? 
>> 
>> I suppose where this discussion is heading is: What is the possibility 
>> of adding a recycling boundary condition explicity in Nek, such that 
>> you can apply it like any other boundary condition, say R for example. 
>> So, in the routine you now search for this recycling flag 'R', and 
>> then run through the setup, rescale etc...? 
>> 
>> -Michael 
>> 
>> ----- Original Message ----- 
>> From: nek5000-users at lists.mcs.anl.gov 
>> To: nek5000-users at lists.mcs.anl.gov 
>> Sent: Friday, July 16, 2010 4:47:11 PM GMT -06:00 US/Canada Central 
>> Subject: Re: [Nek5000-users] New Recycling BC based on interpolation 
>> 
>> 
>> Hi Michael, 
>> 
>> Use whatever discrimination you like --- I would not suggest 
>> modifying the character bcs, however, save that you can enter 
>> values in bc(k,f,e,1) for k > 1, for any cbc(f,e,1) = 'v ' 
>> 
>> The reason for this is that nek checks explicitly for cbc='v ' 
>> (v, followed by two spaces) in many locations. 
>> 
>> The correct place for discriminating parameters is in the 
>> arracy bc(). 
>> 
>> Normally I discriminate by geometry --- e.g., x < x0, or 
>> something similar, occasionally involving the unit normals on 
>> the face in question - as that can be a stronger discriminator. 
>> 
>> Paul 
>> 
>> 
>> On Fri, 16 Jul 2010, nek5000-users at lists.mcs.anl.gov wrote: 
>> 
>>> Hi Aleks, 
>>> 
>>> Thank you very much for looking into this. I already have a question; I 
>>> noticed that you marked several notes dealing with "RBC single inlet -- 
>>> modify for other cases". I am assuming this means that you have one inlet 
>>> that you want to recycle, but another inlet that you do not want to 
>>> recycle, which just happens to be my case. 
>>> 
>>> Can I distinguish in the rea between the two by "v1 " and "v2 " without 
>>> giving genmap any problems, and then modify the checks in the usr file 
>>> accordingly? Also, the subroutine rescale_inflow mentions to modify for 
>>> multiple inlets as well but I do not see where any modification 
>>> could/needs to be done for it. 
>>> 
>>> - Michael 
>>> 
>>> ----- Original Message ----- 
>>> From: nek5000-users at lists.mcs.anl.gov 
>>> To: nek5000-users at lists.mcs.anl.gov 
>>> Sent: Friday, July 16, 2010 3:03:52 PM GMT -06:00 US/Canada Central 
>>> Subject: [Nek5000-users] New Recycling BC based on interpolation 
>>> 
>>> Hi Michael and Markus, 
>>> 
>>> Here is a test case for an unsteady pipe flow with Michael's 
>>> GambitPipe.rea file which sets inlet Recycling BCs based on interpolation 
>>> from a cross-section downstream that you specify by a multiple of the 
>>> inlet normal: 
>>> 
>>> http://www.mcs.anl.gov/~obabko/z4.tgz 
>>> 
>>> 
>>> Let me know if you have any questions. 
>>> Best, 
>>> Aleks 
>>> 
>>> 
>>> 
>>> 
>>> ----- Original Message ----- 
>>> From: nek5000-users at lists.mcs.anl.gov 
>>> To: nek5000-users at lists.mcs.anl.gov 
>>> Sent: Thursday, July 8, 2010 5:06:48 PM GMT -06:00 US/Canada Central 
>>> Subject: Re: [Nek5000-users] New Recycling BC method? 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> No worries, just checkin in to see how it was going, thanks for the 
>>> update! Look forward to trying it out! 
>>> 
>>> 
>>> 
>>> - Michael 
>>> 
>>> _______________________________________________ 
>>> 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 
>> 
> _______________________________________________ 
> 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/20100716/e73e2960/attachment.html>