[esp-r] Re: CFD conflation options

[Andrew Cowie]

Thanks Achim,

I appreciate that the CFD in ESP-r is seldom used, but I figured someone on here must have coded it!

The recent email was in regard to overall conflation options, specified on line 2 of the dfd file "*conflation #". A quick grep of the exemplars reveals instances of conflation 0, 1 and 4. I know 4 is adaptive, inferring from the old help text I guess 0 is CFD only, but 1 is a mystery to me; it seems to basically work (though I can't get it to converge) but the help text suggests that this is a defunct mode that was superceded by the adaptive conflation controller. Tests confirm that conflation types 2 and 3 no longer function correctly.

In regard to your answers, I had essentially a "no" from Aizaz for question 1 of my first three questions, which is interesting as it would mean that there is currently no supported means of conflating the airflow. My tests so far seem to confirm this, as conflation 4 will generally either refuse to converge or throw up an error in mfsolv when the airflow network is included. Occasionally it can be coerced to converge, but this takes a great deal of reducing the relaxation factors and at least 10,000 iterations, so I can't help but feel it's not working quite right. This is quite frustrating as I'm trying to create case study models which are subject to largely wind-driven airflow. It is possible though that it does technically work but my model is too complex to get a solution, this is my next avenue of investigation.

For question 2 from my first three I found an option in CFD boundary condition creation that appears to correctly conflate openings with airflow connections. This creates extra nodes in the airflow network, but these are "hidden" nodes as they do not appear in the afn file. This seems reasonable considering what I know of the conflation mechanisms, so I can only assume that the code to do it still exists despite the retirement of conflation type 3 and the apparent non-applicability of conflation type 4.

I would love nothing more than to spend months doggedly un-picking these tangles from the code, but unfortunately I have a thesis due in fairly short order, so any ideas for "quick-fix" workarounds anyone may have would be very helpful.

Thanks all,
Andy

Sent from mobile


----- Reply message -----
From: "Achim Geissler" <achim.geissler at intergga.ch>
To: "Andrew Cowie" <cn06arc at leeds.ac.uk>
Cc: "esp-r at lists.strath.ac.uk" <esp-r at lists.strath.ac.uk>
Subject: [esp-r] CFD conflation options
Date: Sat, Jul 27, 2013 17:24



Hi Andy

it does not look like you will be receiving many answers, sadly. As my usage of CFD with conflation an all is a few years back, I hesitated to give any answers as these must stay vague.

In regard to
1. below, it is probably easiest to do a code-crawl and find out which conflation types are still in the code (I expect that none have been actually removed, so maybe one would need to do tests). In an old model, I found conflation type entries 3, 4 and 11 for the surfaces.
2. said model also used an air flow network, so yes, there  should be no problem, here

In regard to 1, 2 and 3 from your original mail
1. Based on said model from above, I would say the answer is "yes"
2. I can't see any unusual entries in the files, so probably "no"
3. pass

Sorry that I can't give any more detailed information. Maybe someone else will now feel the urge to set me right and chime in …

Cheers
Achim

On Jul 27, 2013, at 3:13 PM, Andrew Cowie <cn06arc at leeds.ac.uk> wrote:

> Hi all,
>
> Further to my previous set of questions, i notice that the help text on the Bsim-CFD conflation options is still woefully out of date.  So i have a few further questions:
>
> 1. Exactly what conflation options are still supported?
> 2. Is there one which will allow me to conflate both the building simulation AND the airflow network to the CFD? If so which one?
>
> I will do my best to update the help text with this info once i start cataloging and commiting my developments.
>
> Thanks in anticipation,
> Andy Cowie
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achim.geissler at intergga.ch