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Fire Dynamics Simulator
https://pages.nist.gov/fds-smv/
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WFDS #11766

Closed Weggins closed 1 year ago

Weggins commented 1 year ago

Hi everyone, I am trying to establish a model to simulate the fire spread on a canyon terrain. I use 'GEOM' to realize a canyon terrain and I use the parameters about vegetation which is referred to in hill_structure_bench.fds. However, it is a pity that I cannot see the fire spread. I hope someone can give me some advise. The commands are the following: &MESH ID='canyon', IJK=80,70,50, XB=-4.0,4.0,-1.0,6.0,0.0,5.0/

&REAC ID='WOOD' FUEL='WOOD' FYI='Ritchie, et al., 5th IAFSS, C_3.4 H_6.2 O_2.5, dHc = 15MW/kg' SOOT_YIELD = 0.02 O = 2.5 C = 3.4 H = 6.2 HEAT_OF_COMBUSTION = 17700 /

&SPEC ID='WATER VAPOR' /

&SURF ID = 'GRASS' MATL_ID = 'Dry Grass' MASS_PER_VOLUME = 12 THICKNESS= 0.51 MOISTURE_FRACTION= 0.06 SURFACE_VOLUME_RATIO = 12240 EMISSIVITY = 0.99 RGB = 122,117,48 /

&MATL ID = 'AIR' DENSITY = 1.2 CONDUCTIVITY = 0.026 SPECIFIC_HEAT = 1.01 /

&MATL ID = 'MOISTURE' DENSITY = 997. CONDUCTIVITY = 0.62 SPECIFIC_HEAT = 4.184 A = 600000. E = 48200. N_T = -0.5 SPEC_ID = 'WATER VAPOR' NU_SPEC = 1.0 HEAT_OF_REACTION = 2259. /

&MATL ID = 'Dry Grass' DENSITY = 512. CONDUCTIVITY = 0.11 SPECIFIC_HEAT = 1.5 A = 36300. E = 60300. MATL_ID = 'Char' NU_MATL = 0.2 SPEC_ID = 'WOOD' NU_SPEC = 0.8 HEAT_OF_REACTION = 711. /

&MATL ID = 'Char' DENSITY = 300. CONDUCTIVITY = 0.052 SPECIFIC_HEAT = 1. / N_S = 0. NU_O2_CHAR = 1.65 BETA_CHAR = 0.2 A = 430. E = 74800. MATL_ID = 'Ash' NU_MATL = 0.0227273 SPEC_ID = 'PRODUCTS' NU_SPEC = 0.9965 HEAT_OF_REACTION = -32370. /

&MATL ID = 'Ash' DENSITY = 67. CONDUCTIVITY = 0.1 SPECIFIC_HEAT = 2.0 /

&GEOM ID='terrain', SURF_ID='GRASS', IS_TERRAIN=T,BNDF_GEOM=T, VERTS= -3.5,0.0,2.0, -3.5,6.0,2.0, -0.1,0.0,0.0, -0.1,6.0,0.0, 0.1,0.0,0.0, 0.1,6.0,0.0, 3.5,0.0,2.0, 3.5,6.0,2.0, FACES= 1,4,2,1, 1,3,4,1, 3,6,4,1, 3,5,6,1, 5,8,6,1, 5,7,8,1/ &SURF ID='fire',HRRPUA=1000,RAMP_Q='RAMPIGN',RGB=255,0,0,/ &RAMP ID='RAMPIGN',T= 0,F=1 / &RAMP ID='RAMPIGN',T= 20,F=1 / &RAMP ID='RAMPIGN',T= 21,F=0 / &VENT XB=-0.1,0.1,0.5,0.7,0.0,0.0,SURF_ID='fire'/

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

&BNDF QUANTITY='WALL TEMPERATURE'/ &BNDF QUANTITY='WALL THICKNESS'/ &BNDF QUANTITY='BURNING RATE'/ &BNDF QUANTITY='RADIATIVE HEAT FLUX'/ &BNDF QUANTITY='CONVECTIVE HEAT FLUX'/

&TAIL /

ericvmueller commented 1 year ago

Add GEOM = T to ensure your ignition is applied to the complex geometry: &VENT XB=-0.1,0.1,0.5,0.7,0.0,0.0,SURF_ID='fire', GEOM = T/

I'd also suggest having it ramp up over the first second or so, rather than start at full HRRPUA. Testing now but it looks like the fire is spreading.