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AMPUA Issue #6646

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jutrasi opened this issue Jul 17, 2018 · 4 comments
Closed

AMPUA Issue #6646

jutrasi opened this issue Jul 17, 2018 · 4 comments
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@mcgratta

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@jutrasi
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jutrasi commented Jul 17, 2018

I am running a simple sprinkler spray case and collecting the water using AMPUA with STATISTICS='SURFACE INTEGRAL'. Bucket 1 is located directly under the sprinkler and buckets 2 and 3 are located to the right and left of bucket 1. I also have a 4th larger bucket that encompasses the entire floor area. The spray is directed only into bucket 1. In the 3 seconds of spray, I am only discharging a total of 1 liter (1 kg) of water. The total bucket and the value in bucket 1 confirms that there is only 1 kg of water discharged. However, buckets 2 and 3 show 0.48 and 0.5 kg of water, respectively. This concludes that there was actually 2 kg of water discharged which is not the case. I have also decreased the mesh size and it still occurs but to a lesser degree. I appreciate any thoughts with this.

&HEAD CHID='SprayTest',TITLE='SprayTest'/


&MESH IJK=20,20,20, XB=-0.5,0.5,-0.5,0.5,1,2/

&TIME T_END=5/

&SPEC ID='WATER VAPOR'/

&PART ID='WATER DROPS',SPEC_ID='WATER VAPOR', QUANTITIES(1:3)='PARTICLE DIAMETER','PARTICLE TEMPERATURE','PARTICLE AGE',
      DIAMETER=1200., SAMPLING_FACTOR=1,CHECK_DISTRIBUTION=.TRUE. /

&DEVC XYZ=0,0,1.9, PROP_ID='SP',ORIENTATION=0,0,-1,  QUANTITY='TIME',SETPOINT=0, ID='noz_1' /


&PROP ID='SP', QUANTITY='SPRINKLER LINK TEMPERATURE', PART_ID='WATER DROPS',K_FACTOR=50, FLOW_RATE=20, OFFSET=0,PARTICLES_PER_SECOND=1000,FLOW_RAMP='flow',SPRAY_ANGLE=0,2, PARTICLE_VELOCITY=10./ 
&RAMP ID='flow', T=0, F=1/ 
&RAMP ID='flow', T=2.99, F=1/
&RAMP ID='flow', T=3, F=0/


&BNDF QUANTITY='AMPUA', PART_ID='WATER DROPS'/

&VENT MB='XMIN', SURF_ID='OPEN' /
&VENT MB='XMAX', SURF_ID='OPEN' /
&VENT MB='YMIN', SURF_ID='OPEN' /
&VENT MB='YMAX', SURF_ID='OPEN' /


&DEVC XB=-0.05,0.05,-0.05,0.05,1,1, QUANTITY='AMPUA',STATISTICS='SURFACE INTEGRAL', PART_ID='WATER DROPS', ID='bucket-1'/
&DEVC XB=0.05,0.15,-0.05,0.05,1,1, QUANTITY='AMPUA',STATISTICS='SURFACE INTEGRAL', PART_ID='WATER DROPS', ID='bucket-2'/
&DEVC XB=-0.15,-0.05,-0.05,0.05,1,1, QUANTITY='AMPUA',STATISTICS='SURFACE INTEGRAL', PART_ID='WATER DROPS', ID='bucket-3'/

&DEVC XB=-0.2,0.2,-0.2,0.2,1,1, QUANTITY='AMPUA',STATISTICS='SURFACE INTEGRAL', PART_ID='WATER DROPS', ID='total'/

&TAIL/
@drjfloyd
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If I make the second device XB=0.501,0.15 and the third -0.15,-0.501, then the mass in those devices goes to zero. It looks like some form of precision error in picking which wall cells belong to which devices (0.5 expressed in binary is actually going to be something that looks like 0.499999999 or 0.500000001).

@jutrasi
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jutrasi commented Jul 18, 2018

Thanks for the quick response. I have tried this method with a number of other cases and it still seems like there is an issue. I have also tried with larger gaps between the buckets of 0.01 m as seen below. With this, I am still running into this problem where there is more water in the sum of all the buckets (1-4) than what is actually being released by the sprinkler. I noticed this issue when upgrading from version 6.5.3 to 6.7.

&HEAD CHID='SprayTest2',TITLE='SprayTest2'/


&MESH IJK=20,20,20, XB=-0.5,0.5,-0.5,0.5,1,2/

&TIME T_END=5/

&SPEC ID='WATER VAPOR'/

&PART ID='WATER DROPS',SPEC_ID='WATER VAPOR', QUANTITIES(1:3)='PARTICLE DIAMETER','PARTICLE TEMPERATURE','PARTICLE AGE',
      DIAMETER=1200., SAMPLING_FACTOR=1,CHECK_DISTRIBUTION=.TRUE. /

&DEVC XYZ=0,0,1.9, PROP_ID='SP',ORIENTATION=0,0,-1,  QUANTITY='TIME',SETPOINT=0, ID='noz_1' /

&PROP ID='SP', QUANTITY='SPRINKLER LINK TEMPERATURE', PART_ID='WATER DROPS',K_FACTOR=50, FLOW_RATE=20, OFFSET=0,PARTICLES_PER_SECOND=1000,FLOW_RAMP='flow',SPRAY_PATTERN_TABLE='spray'/ 
&RAMP ID='flow', T=0, F=1/ 
&RAMP ID='flow', T=2.99, F=1/
&RAMP ID='flow', T=3, F=0/


&TABL ID='spray', TABLE_DATA=0,6,180,360,20,1/

&BNDF QUANTITY='AMPUA', PART_ID='WATER DROPS'/

&VENT MB='XMIN', SURF_ID='OPEN' /
&VENT MB='XMAX', SURF_ID='OPEN' /
&VENT MB='YMIN', SURF_ID='OPEN' /
&VENT MB='YMAX', SURF_ID='OPEN' /


&DEVC XB=-0.05,0.05,-0.05,0.05,1,1, QUANTITY='AMPUA',STATISTICS='SURFACE INTEGRAL', PART_ID='WATER DROPS', ID='bucket-1'/
&DEVC XB=0.06,0.15,-0.05,0.05,1,1, QUANTITY='AMPUA',STATISTICS='SURFACE INTEGRAL', PART_ID='WATER DROPS', ID='bucket-2'/
&DEVC XB=-0.15,-0.06,-0.05,0.05,1,1, QUANTITY='AMPUA',STATISTICS='SURFACE INTEGRAL', PART_ID='WATER DROPS', ID='bucket-3'/
&DEVC XB=-0.15,0.15,0.06,0.1,1,1, QUANTITY='AMPUA',STATISTICS='SURFACE INTEGRAL', PART_ID='WATER DROPS', ID='bucket-4'/

&DEVC XB=-0.5,0.5,-0.5,0.5,1,1, QUANTITY='AMPUA',STATISTICS='SURFACE INTEGRAL', PART_ID='WATER DROPS', ID='total'/

&TAIL/

@mcgratta
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I'll take a look at this.

mcgratta added a commit to mcgratta/fds that referenced this issue Jul 23, 2018
@mcgratta
FDS Source: Issue firemodels#6646. Fix bug in SURFACE AREA stats
94861f1
mcgratta added a commit that referenced this issue Jul 23, 2018
@mcgratta
Merge pull request #6664 from mcgratta/master
ed42748 
FDS Source: Issue #6646. Fix bug in SURFACE AREA stats
@mcgratta
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This was a bug. I fixed it, so that now the buckets add up to the right amount.

@Er9y714 Er9y714 mentioned this issue Dec 18, 2018
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@mcgratta @drjfloyd @jutrasi