[esp-r] Underrelaxing by using Timestep-controller 4

[Pueltz, Gunter]

Dear ESP-specialists and developer,

for a simulation project with 2 big rooms, which are connected by a large opening and thus show an intensive bidirectional air flow (= intensive air exchange between the 2 zones, see attached screenshot Simulation-model.png), I am using Timestep-controller 4 and a small timestep (10 min). 
If I do NOT use the underrelaxation-method for the new air-flow-values (the default in source file mfmach.F is, that the do-loop 2222 for underrelaxing the new air-flow-values is commented out; see mFmach.F line 522 - 530 resp. attached screenshot mFmach-line522-530.png), ESP struggles with very intensive oscillations (see attached screenshot results-without-relaxation.png). 
If this underrelaxation do-loop 2222 is activated (relaxation-factor = 0.25), these oscillations do not appear anymore (see attached screenshot results-with-relaxation.png).
The first thing I want to point out is, that these results induce NOT to comment out this underrelaxation do-loop 2222 in future versions of ESP-r !

If the do-loop 2222 is activated manually, a second problem occurs unfortunately : 
The boolean variable itrpas should be greater zero, if timestep-controller 4 is used (see mfmach.F, line 523). But I found, that itrpas ALWAYS is zero, even while using timestep-controller 4 !?!?! For me it seems, that itrpas is not set to its correct value ...
I would like to recommend the ESP-developers to fix this bug ;-)

Moreover I am wondering that only one, single user of ESP-r seems to face this problem with oscillations, which are caused by large openings between two thermal domains within a building, inducing an intensive air exchange ... ??? 

-Gunter
  


--

Dr. Gunter Pültz

Müller-BBM GmbH 
Robert-Koch-Straße 11 
82152 Planegg 
Telefon +49(89)85602-336 
Telefax +49(89)85602-111 
E-Mail Gunter.Pueltz at MuellerBBM.de 
http://www.MuellerBBM.de 

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