Boundary fuel models Rothermel-Albini

[Marina Simó Martí]

Hello,

I'm trying to set a boundary fuel model area smaller than my scenario domain. When I  use the veg_lset_fuel_index option to set a Rothermel vegetation model, it defines the surface fuel model for my whole domain area, and not for the small area I've specified in the &surf line. Is it possible to do what I'm attempting to?

These are the lines I've typed:

&MESH IJK=280,180,70, XB=-40,240,-40,140,0,70/  My mesh

&MISC LEVEL_SET_MODE=4 /

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

&SURF ID='Custom grass', DEFAULT=T, VEG_LSET_FUEL_INDEX=4 /
&VENT SURF_ID='Custom grass', XB=0,200,0,100,0,0, COLOR = 'GREEN' / This is the area where I want the boundary fuel model to be set

Thank you,

Marina

[Marina Simó Martí]

Actually, when I load the .smv file in Smokeview, this is what appears:

First, Photo1.png , where the whole area is covered.

Second, if I hide the "terrain" in the panel options then I can see the "custom grass" &vent created with the color and the dimensions I've specified. But I don't know if the boundary model is applied just to that vent or to my whole mesh as it seems in the first photo.

[Kevin McGrattan]

We need to see the full input file.

[Marina Simó Martí]

You can find it attached here. (There is also a bulk density binary file for the shrub and tree layer but I cannot upload it.)

[Kevin McGrattan]

When I run the case without the INIT line, I see a green patch like your second picture. I suggest that you create a more coarsely gridded case and try some trivial example to test whether the boundary fuel model is applied to the right surface. I cannot test your actual case without the missing file.

[Kevin McGrattan]

WARNING: Two VENTs overlap in MESH 1, Cell 122 41 0 . VENT 7 rejected for that cell

This means that FDS uses the first VENT if there is an overlap.

[Marina Simó Martí]

Yes, there is an overlap because I'm trying to set a fire as a VENT. Otherwise I don't how I should define my ignition point, as an obstruction maybe?

[Kevin McGrattan]

Put the fire vent in front of the other vent in the input file.

[Marina Simó Martí]

Alright, by doing it, the VENTS do not overlap and the fire spreads properly. However, the fire spreads all over my domain and not just through the smaller area specified, which means that the surface fuel model is applied to my whole domain surface. Any idea of how can I apply a boundary fuel model to a specified area? Or maybe by defining deifferent meshes I can do what I attempt to?

[Kevin McGrattan]

Post the most simple version of your file that demonstrates the problem.