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QF-Error-Tracking / QFVD5

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QF v311 and v502 differences in fire shape and fuel_density for Linefire #7

Closed JayCh1 closed 1 year ago

JayCh1 commented 1 year ago

Describe the bug I have run QF v311 and v502 using what appear to be identical fuel, fire start, and winds, and am getting different fire shapes and fuel_density values in the output files

To Reproduce http://35.12.130.8/study/jay/working/qf5/ or Email: charneyjay@gmail.com

Desktop (please complete the following information):

Screenshots png images in the link show:

fuel density at final time surface uwind at final time level 10 wwind at final time

zacharycope0 commented 1 year ago

Jay,

The two QUIC_fire.inp files that you shared will have different fuel densities. When using uniform fuels the fuel height value acts as a scalar. In the V3.1.1 file you have a value of 1 m and for V5.0.2 you have a value of 0.7 m.

QUIC_fire.inp V3.1.1

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QUIC_fire.inp V5.0.2

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I'm going to close this issue. Please reopen if your still seeing differences after modifying the input files.

JayCh1 commented 1 year ago

I changed .7 to 1.0 in the v502 run, and now I get a fire shape that is more continuous. However, the background/unburnt fuel_density is larger but still still quite a bit lower than in the V311 runs. All v502 files have been updated at:

http://35.12.130.8/study/jay/working/qf5/

zacharycope0 commented 1 year ago

@JayCh1. I tracked down the problem. You set your fire grid height to 2m and your fuel height to 1m. Therefore your cells are half filled with fuel have a bulk density value that is half of what you expected. We typically run the fuel gird cells with a uniform height of 1m.

image

JayCh1 commented 1 year ago

@zacharycope0 This fixed the problem and the fuel density outputs are now consistent with v311.

Looking at the samples that were distributed with V502 and comparing then with the examples I was using for 311, the LineFire sample is the only 502 sample with the fire grid height set to 2. That's what tripped me up. I also note that the LineFire is the only sample with a Surface DZ of 1.5 in QU_simparams (all the others are 1.0). I'm not sure why that is, but in case it matters in the future I thought I would point that out as well.

Thanks for sussing this out.