Special Applications¶
Specialized simulation types for specific scenarios and research applications.
Overview¶
These examples demonstrate PyFDS for specialized applications:
- Wildfire and vegetation fires
- Heat transfer only (no combustion)
- Sprinkler system activation
- Aircraft and vehicle fires
- Industrial scenarios
Wildfire Simulation¶
Large-scale outdoor fire with vegetation and wind.
from pyfds import Simulation
sim = Simulation(chid='wildfire')
sim.add(Time(t_end=1800.0)) # 30 minutes
# Large outdoor domain (100m × 100m × 30m)
sim.add(Mesh(ijk=Grid3D.of(100, 100, 30), xb=Bounds3D.of(0, 100, 0, 100, 0, 30)))
# Hot, dry, windy conditions
sim.set_misc(
tmpa=35.0, # Hot day (35°C)
humidity=15.0, # Low humidity
wind_speed=5.0, # 5 m/s wind
wind_direction=270.0 # From west (blowing east)
)
# Open boundaries for wind flow
for mb in ['XMIN', 'XMAX', 'YMIN', 'YMAX', 'ZMAX']:
sim.add(Vent(mb=mb, surf_id='OPEN'))
# Vegetation fuel (grass/brush)
sim.add(Reaction(
id='VEGETATION',
fuel='CELLULOSE',
heat_of_combustion=15000.0,
soot_yield=0.015,
co_yield=0.004
)
# Initial fire line (ignition source)
sim.add(Surface(
id='IGNITION',
hrrpua=500.0,
reac_id='VEGETATION',
color='ORANGE'
)
# Fire starts along western edge
sim.add(Obstruction(
xb=Bounds3D.of(10, 15, 45, 55, 0, 0.5),
surf_id='IGNITION'
)
# Temperature measurements downwind
for x in [30, 50, 70, 90]:
sim.add(Device(
id=f'TEMP_X{x}',
quantity='TEMPERATURE',
xyz=Point3D.of(x, 50, 2)
)
# Heat flux to potential targets
for x in [60, 80]:
sim.add(Device(
id=f'HF_X{x}',
quantity='GAUGE HEAT FLUX',
xyz=Point3D.of(x, 50, 2),
ior=1 # Facing fire
)
sim.write('wildfire.fds')
Features: - Large outdoor domain - Wind-driven fire spread - Vegetation fuel properties - Downwind temperature and heat flux monitoring
Heat Transfer Only¶
Thermal analysis without combustion (pure conduction/radiation).
from pyfds import Simulation
sim = Simulation(chid='heat_transfer')
sim.add(Time(t_end=3600.0)) # 1 hour
sim.add(Mesh(ijk=Grid3D.of(60, 40, 30), xb=Bounds3D.of(0, 3, 0, 2, 0, 1.5)))
# Disable combustion
sim.set_misc(no_combustion=True)
# Steel structure properties
sim.add(Material(
id='STEEL',
conductivity=45.8,
specific_heat=0.46,
density=7850.0
)
sim.add(Surface(
id='STEEL_SURF',
matl_id='STEEL',
thickness=0.01, # 10mm steel plate
emissivity=0.85
)
# Hot boundary (fire exposure side)
sim.add(Surface(
id='HOT_BC',
tmp_front=800.0, # 800°C constant temperature
color='RED'
)
# Steel plate between hot and cold sides
sim.add(Obstruction(
xb=Bounds3D.of(1.45, 1.55, 0, 2, 0, 1.5),
surf_id='STEEL_SURF'
)
# Hot side exposure
sim.add(Vent(
xb=Bounds3D.of(0, 0, 0, 2, 0, 1.5),
surf_id='HOT_BC'
)
# Cold side (ambient)
sim.add(Vent(
xb=Bounds3D.of(3, 3, 0, 2, 0, 1.5),
surf_id='OPEN'
)
# Temperature through steel plate
for i, x in enumerate([1.45, 1.475, 1.50, 1.525, 1.55]):
sim.add(Device(
id=f'TEMP_STEEL_{i}',
quantity='TEMPERATURE',
xyz=Point3D.of(x, 1, 0.75)
)
# Heat flux on cold side
sim.add(Device(
id='HF_COLD_SIDE',
quantity='GAUGE HEAT FLUX',
xyz=Point3D.of(1.56, 1, 0.75),
ior=1
)
sim.write('heat_transfer.fds')
Features: - No combustion (thermal only) - Temperature boundary conditions - Heat conduction through materials - Temperature gradient measurement
Sprinkler System¶
Automatic sprinkler activation with suppression.
from pyfds import Simulation
sim = Simulation(chid='sprinkler_system')
sim.add(Time(t_end=600.0))
sim.add(Mesh(ijk=Grid3D.of(80, 60, 30), xb=Bounds3D.of(0, 8, 0, 6, 0, 3)))
# Fire growing over time
sim.add(Ramp(id='FIRE_GROWTH', t=[0, 120, 300], f=[0, 0.5, 1.0]))
sim.add(Surface(id='FIRE', hrrpua=2000.0, ramp_q='FIRE_GROWTH'))
sim.add(Obstruction(xb=Bounds3D.of(3.5, 4.5, 2.5, 3.5, 0, 0.1), surf_id='FIRE'))
# Sprinkler heads (4 heads, K-factor 80)
sprinkler_locations = [
(2, 2, 2.95),
(6, 2, 2.95),
(2, 4, 2.95),
(6, 4, 2.95)
]
for i, (x, y, z) in enumerate(sprinkler_locations):
# Temperature link for each sprinkler
sim.add(Device(
id=f'LINK_{i+1}',
quantity='TEMPERATURE',
xyz=Point3D.of(x, y, z)
)
# Control: Activate at 68°C (typical sprinkler)
sim.add(Control(
id=f'SPRINKLER_{i+1}_CTRL',
input_id=f'LINK_{i+1}',
setpoint=68.0,
latch=True # Once activated, stays on
)
# Water spray surface
sim.add(Surface(
id=f'SPRAY_{i+1}',
mass_flux=0.05, # Water spray rate (kg/m²/s)
tmp_front=20.0, # Water temperature
ctrl_id=f'SPRINKLER_{i+1}_CTRL'
)
# Spray vent
sim.add(Vent(
xb=Bounds3D.of(x-0.2, x+0.2, y-0.2, y+0.2, z, z),
surf_id=f'SPRAY_{i+1}'
)
# Monitor temperatures
for loc, (x, y) in [('FIRE', (4, 3)), ('CORNER', (1, 1))]:
sim.add(Device(
id=f'TEMP_{loc}',
quantity='TEMPERATURE',
xyz=Point3D.of(x, y, 2.5)
)
# Monitor HRR (will decrease after sprinkler activation)
sim.add(Device(
id='HRR',
quantity='HRR',
xyz=Point3D.of(4, 3, 1.5)
)
sim.write('sprinkler_system.fds')
Features: - Multiple sprinkler heads with thermal links - Automatic activation controls - Water spray suppression - Fire suppression monitoring
Aircraft Cabin Fire¶
Aircraft interior fire scenario.
from pyfds import Simulation
sim = Simulation(chid='aircraft_fire')
sim.add(Time(t_end=600.0))
# Aircraft cabin dimensions (20m long × 3m wide × 2m high)
sim.add(Mesh(ijk=Grid3D.of(100, 30, 20), xb=Bounds3D.of(0, 20, 0, 3, 0, 2)))
# Cabin materials (composite/aluminum)
sim.add(Material(
id='AIRCRAFT_PANEL',
conductivity=0.25,
specific_heat=1.0,
density=1600.0
)
sim.add(Surface(
id='CABIN_WALL',
matl_id='AIRCRAFT_PANEL',
thickness=0.003, # 3mm panels
color='GRAY'
)
# Cabin walls
sim.add(Obstruction(xb=Bounds3D.of(0, 20, 0, 0.1, 0, 2), surf_id='CABIN_WALL'))
sim.add(Obstruction(xb=Bounds3D.of(0, 20, 2.9, 3, 0, 2), surf_id='CABIN_WALL'))
sim.add(Obstruction(xb=Bounds3D.of(0, 20, 0, 3, 1.95, 2), surf_id='CABIN_WALL'))
# Seat fire (polyurethane foam)
sim.add(Reaction(
id='FOAM',
fuel='POLYURETHANE',
heat_of_combustion=25000.0,
soot_yield=0.131,
co_yield=0.042,
radiative_fraction=0.40
)
sim.add(Surface(id='SEAT_FIRE', hrrpua=800.0, reac_id='FOAM'))
# Burning seat at row 10
sim.add(Obstruction(
xb=Bounds3D.of(9.5, 10, 0.5, 1.5, 0.4, 1.2),
surf_id='SEAT_FIRE'
)
# Emergency exits
sim.add(Vent(xb=Bounds3D.of(0, 0, 1, 2, 0, 1.8), surf_id='OPEN') # Forward
sim.add(Vent(xb=Bounds3D.of(20, 20, 1, 2, 0, 1.8), surf_id='OPEN') # Aft
# Dense monitoring along aisle
for x in range(2, 19, 2):
# Temperature at head height (seated)
sim.add(Device(
id=f'TEMP_X{x:02d}',
quantity='TEMPERATURE',
xyz=Point3D.of(x, 1.5, 1.0)
)
# Visibility (critical for evacuation)
sim.add(Device(
id=f'VIS_X{x:02d}',
quantity='VISIBILITY',
xyz=Point3D.of(x, 1.5, 1.0)
)
# CO concentration (toxic)
sim.add(Device(
id=f'CO_X{x:02d}',
quantity='VOLUME FRACTION',
spec_id='CARBON MONOXIDE',
xyz=Point3D.of(x, 1.5, 1.0)
)
sim.write('aircraft_fire.fds')
Features: - Confined aircraft geometry - Polyurethane foam fire (high soot) - Visibility along evacuation path - Toxic gas monitoring
Battery Fire (Thermal Runaway)¶
Lithium-ion battery thermal runaway simulation.
from pyfds import Simulation
sim = Simulation(chid='battery_fire')
sim.add(Time(t_end=600.0))
sim.add(Mesh(ijk=Grid3D.of(60, 60, 40), xb=Bounds3D.of(0, 3, 0, 3, 0, 2)))
# Battery thermal runaway characteristics
sim.add(Ramp(
id='THERMAL_RUNAWAY',
t=[0, 30, 60, 90, 120, 600],
f=[0, 0.5, 1.0, 0.8, 0.3, 0.1] # Rapid onset, gradual decay
)
# Battery fire (high heat, moderate smoke)
sim.add(Surface(
id='BATTERY_FIRE',
hrrpua=1500.0,
ramp_q='THERMAL_RUNAWAY',
color='ORANGE'
)
# Battery pack (small footprint, intense heat)
sim.add(Obstruction(
xb=Bounds3D.of(1.4, 1.6, 1.4, 1.6, 0.5, 0.7),
surf_id='BATTERY_FIRE'
)
# Thermal propagation to adjacent batteries
sim.add(Device(
id='TEMP_ADJACENT_1',
quantity='TEMPERATURE',
xyz=Point3D.of(1.7, 1.5, 0.6)
)
sim.add(Device(
id='TEMP_ADJACENT_2',
quantity='TEMPERATURE',
xyz=Point3D.of(1.3, 1.5, 0.6)
)
# Heat flux to surrounding objects
for angle in [0, 90, 180, 270]:
import math
r = 0.5 # 0.5m from battery
x = 1.5 + r * math.cos(math.radians(angle))
y = 1.5 + r * math.sin(math.radians(angle))
sim.add(Device(
id=f'HF_{angle}DEG',
quantity='GAUGE HEAT FLUX',
xyz=Point3D.of(x, y, 0.6),
ior=1
)
# Toxic gas monitoring (HF from electrolyte)
# Note: Simplified - real battery fires produce complex chemistry
sim.add(Device(
id='SMOKE_DETECTOR',
quantity='OPTICAL DENSITY',
xyz=Point3D.of(1.5, 1.5, 1.8)
)
sim.write('battery_fire.fds')
Features: - Thermal runaway growth curve - Small, intense heat source - Thermal propagation monitoring - Radial heat flux measurements
Industrial Process Fire¶
Chemical plant/industrial scenario.
from pyfds import Simulation
sim = Simulation(chid='industrial_fire')
sim.add(Time(t_end=900.0))
# Large industrial space
sim.add(Mesh(ijk=Grid3D.of(120, 80, 50), xb=Bounds3D.of(0, 24, 0, 16, 0, 10)))
# Concrete structure
sim.add(Material(id='CONCRETE', conductivity=1.8, specific_heat=0.88, density=2400.0))
sim.add(Surface(id='CONCRETE_WALL', matl_id='CONCRETE', thickness=0.3))
# Walls
sim.add(Obstruction(xb=Bounds3D.of(0, 0.3, 0, 16, 0, 10), surf_id='CONCRETE_WALL'))
sim.add(Obstruction(xb=Bounds3D.of(23.7, 24, 0, 16, 0, 10), surf_id='CONCRETE_WALL'))
# Flammable liquid pool fire (heptane)
sim.add(Reaction(
id='HEPTANE',
fuel='N-HEPTANE',
heat_of_combustion=44600.0,
soot_yield=0.037,
co_yield=0.010,
radiative_fraction=0.33
)
# Large pool fire
sim.add(Surface(
id='POOL_FIRE',
hrrpua=2500.0,
reac_id='HEPTANE',
color='ORANGE'
)
# 4m diameter pool
sim.add(Vent(
xb=Bounds3D.of(10, 14, 6, 10, 0, 0),
surf_id='POOL_FIRE',
xyz=Point3D.of(12, 8, 0),
radius=2.0
)
# Pressure relief vents at roof
sim.add(Vent(xb=Bounds3D.of(8, 10, 6, 8, 10, 10), surf_id='OPEN'))
sim.add(Vent(xb=Bounds3D.of(14, 16, 6, 8, 10, 10), surf_id='OPEN'))
# Heat flux to critical equipment
equipment_locations = [(6, 4, 3), (18, 4, 3), (12, 12, 3)]
for i, (x, y, z) in enumerate(equipment_locations):
sim.add(Device(
id=f'HF_EQUIPMENT_{i+1}',
quantity='GAUGE HEAT FLUX',
xyz=Point3D.of(x, y, z),
ior=2 # Facing toward center
)
# High-level temperature (roof structure)
for x in [6, 12, 18]:
sim.add(Device(
id=f'TEMP_ROOF_X{x}',
quantity='TEMPERATURE',
xyz=Point3D.of(x, 8, 9.5)
)
sim.write('industrial_fire.fds')
Features: - Large industrial space - Flammable liquid pool fire - Pressure relief venting - Equipment heat exposure
Best Practices for Special Applications¶
1. Wildfire Simulations¶
# Use large domain with open boundaries
sim.add(Mesh(ijk=Grid3D.of(100, 100, 30), xb=Bounds3D.of(0, 100, 0, 100, 0, 30)))
# Realistic wind conditions
sim.set_misc(wind_speed=5.0, wind_direction=270.0, roughness_length=0.1)
# Open all boundaries
for mb in ['XMIN', 'XMAX', 'YMIN', 'YMAX', 'ZMAX']:
sim.add(Vent(mb=mb, surf_id='OPEN'))
2. Heat Transfer Studies¶
# Disable combustion for pure thermal analysis
sim.set_misc(no_combustion=True)
# Use temperature boundary conditions
sim.add(Surface(id='HOT_BC', tmp_front=800.0))
3. Sprinkler Systems¶
# Realistic activation temperature
sim.add(Control(id='SPRINKLER', input_id='LINK', setpoint=68.0, latch=True))
# Appropriate water flux
sim.add(Surface(id='SPRAY', mass_flux=0.05) # kg/m²/s
4. Confined Spaces¶
# Ensure adequate resolution in small spaces
# Aircraft: 0.1-0.2m cells
# Battery enclosure: 0.05-0.1m cells
# Monitor visibility and toxicity
sim.add(Device(id='VIS', quantity='VISIBILITY', xyz=(...)))
sim.add(Device(id='CO', quantity='VOLUME FRACTION', spec_id='CARBON MONOXIDE', xyz=(...)))
Next Steps¶
- Basic Examples - Fundamental simulations
- Advanced Examples - Complex scenarios
- Parametric Studies - Sensitivity analysis
- User Guide - Detailed documentation