Streaking Head Fire in Light Wind

[zacharycope0]

Describe the bug There is almost not flanking fire and the head fire splits into multiply streaks for the following simulation: Fuel Load = 0.5 FMC = 2.5% Fuel Depth = 0.5 Wind Speed = 3

To Reproduce https://drive.google.com/file/d/1N2jxdJM3soWqXQdawgQeC4b1O-E7_kHq/view?usp=sharing

Desktop (please complete the following information):

• QF Version QFVD5.0.2
• OS: Ubuntu 18.04

Screenshots

[drobinson6045]

What was the version where this was ran giving typical headfire shapes?

[zacharycope0]

V401

[drobinson6045]

@zacharycope0 Can you attach some plots of the old behavior you were seeing?

[zacharycope0]

@drobinson6045 Sure thing. By the way these examples all have homogenous FMC of 2.5%.

V4.0.2:

[drosales95]

Hey all,

After running a similar testcase on my end I have found fairly simlar results. To be clear, I did not use DAT files for these runs but instead use the homogeneous fuel flags in QUIC_Fire.inp.

Fuel Density: 0.5, FMC: 0.025, FH: 1

Note that the fire is not spreading in the flanks and backing side of the fire. I will do a similar run lowering the height through the DAT files and report back.

@sbrambilla , do you know if there are any default parameters in the alpha2, or omegarelax or creeping fire that could be causing this?

[sbrambilla]

@drosales95 That has been the behavior for a while (no back spread). It has to do with a variable in the creeping. I think you should talk to him, because he was surprised by the value we're using now, so maybe he was doing some tests and forgot to change it back.

[drosales95]

Thanks for the quick response, Sara! @drobinson6045 , tagging you in here as well.

[zacharycope0]

Issue not present in 5.1.0