Issue object disappears at time = 0 [unphysical pressure]

[rupole1185]

This issue is actually made of two problems.

PROBLEM 1. Update the FDS file to FDS 6.8.0 I run the following file with FDS 6.7.6 and 6.7.7 but I did not manage to execute it with a newer version of FDS. So first point is: why is that?

510562-KRP-P3-CC-L1-Scenario_01-Run_04_ff_680.fds.txt

PROBLEM 2. Unphysical pressure in corridor I have found that when running I generated some unphysical pressure in the corridor (like -800 Pa)

The reason for that is in the two OBST that are disappearing right at time 0.0s.

If I comment these two OBST in the FDS file I obtain a realistic pressure distribution in the corridor [in the range of -30/-40 Pa]

I do not understand why using the CTRL to make these two OBST disappear is leading to incorrect results.

[mcgratta]

Problem 1: The case runs for me, using a single process. What was the error message when you tried to run the case?

[mcgratta]

Problem 2: I cannot debug this case because it is too complicated. Simplify the case so that it is clear that there is a problem. You have an HVAC system and when you remove obstructions you may change the pressure in a way that you did not expect. That does not necessarily mean it is an error.

[drjfloyd]

10.2.3 in the User's Guide says to not remove VENTs attached to HVAC components.

&VENT ID='Vent_01_Apartment', SURF_ID='GYPSUM PLASTER', XB=11.0,11.0,-33.0,-32.2,0.0,0.1/ &OBST ID='Apartment External Wall', XB=11.0,11.2,-33.0,-32.2,0.0,2.0, SURF_ID='GYPSUM PLASTER', CTRL_ID='invert-2'/

[rupole1185]

Allright. So this could be the issue, I have to check it. But is it possible to add a warning when by mistake the user does this?

Ruggero Poletto Managing director

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Il dom 29 ott 2023, 19:15 Jason Floyd @.***> ha scritto:

10.2.3 in the User's Guide says to not remove VENTs attached to HVAC components.

&VENT ID='Vent_01_Apartment', SURF_ID='GYPSUM PLASTER', XB=11.0,11.0,-33.0,-32.2,0.0,0.1/ &OBST ID='Apartment External Wall', XB=11.0,11.2,-33.0,-32.2,0.0,2.0, SURF_ID='GYPSUM PLASTER', CTRL_ID='invert-2'/

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[rupole1185]

Hi,

sorry during the weekend I just quickly read the comments.

For PROBLEM 1. If I execute the run on FDS 6.8.0 using the normal "fds 510562-KRP-P3-CC-L1-Scenario_01-Run_04_ff_680.fds" the simulation stops after 0.3s of computed time. If I instead execute it using "fds_openmp 510562-KRP-P3-CC-L1-Scenario_01-Run_04_ff_680.fds" I get the same behaviour. Not sure why in your case you have a different behaviour

PROBLEM 2. I though what @drjfloyd said could be the problem. But in my analysis I am having ussue with OBST which are controlled by the DEVC "invert" while the one you mentioned is controlled by "invert-2". @mcgratta it is difficult to simplify the case in a way the bug comes out again.

[mcgratta]

Problem 1: I ran the case with the latest "nightly build" of FDS, not the official 6.8.0 release. I will try the official release. It is possible that we fixed the bug that caused the job to stop.

Problem 2: Unless you have made an obvious mistake in the simulation set up, we would have to simplify the case to determine the cause of the problem. We do not have the time to analyze all the cases that come in.

[mcgratta]

I started the case on our linux cluster using the official release. It runs. What does your .err file look like?

 Starting FDS ...

 MPI Process      0 started on burn010.backend

 Reading FDS input file ...

WARNING: SPEC REAC_FUEL is not in the table of pre-defined species. Any unassigned SPEC variables in the input were assigned the properties of nitrogen.

 Fire Dynamics Simulator

 Current Date     : October 30, 2023  11:40:35
 Revision         : FDS-6.8.0-0-g886e009-HEAD
 Revision Date    : Tue Apr 18 07:06:40 2023 -0400
 Compiler         : ifort version 2021.7.1
 Compilation Date : Oct 30, 2023 11:34:42

 MPI Enabled;    Number of MPI Processes:       1
 OpenMP Disabled

 MPI version: 3.1
 MPI library version: Intel(R) MPI Library 2021.7 for Linux* OS

 Job TITLE        :
 Job ID string    : 510562-KRP-P3-CC-L1-Scenario_01-Run_04_ff

 Time Step:      1, Simulation Time:      0.03 s
 Time Step:      2, Simulation Time:      0.06 s
 Time Step:      3, Simulation Time:      0.08 s
 Time Step:      4, Simulation Time:      0.11 s
 Time Step:      5, Simulation Time:      0.14 s
 Time Step:      6, Simulation Time:      0.17 s
 Time Step:      7, Simulation Time:      0.20 s
 Time Step:      8, Simulation Time:      0.22 s
 Time Step:      9, Simulation Time:      0.25 s
 Time Step:     10, Simulation Time:      0.28 s
 Time Step:     20, Simulation Time:      0.56 s
 Time Step:     30, Simulation Time:      0.84 s
 Time Step:     40, Simulation Time:      1.12 s
 Time Step:     50, Simulation Time:      1.39 s

[rupole1185]

This is what I get in my case with 6.8.0

[mcgratta]

I downloaded the release bundle and installed the modules FDS6 and SMV6 according to the installation instructions. Then I logged into one node on our cluster and ran the case as follows: