Animating SuspendedParticle Explosions

Presented at SIGGRAPH 2003 by

Bryan E. Feldman

James F. O’Brien

Okan Arikan

University of California, Berkeley

Reviewed for CS 527 by

John T. Bell

Motivation and Background

• Movies & video games incorporate explosions

• Real pyrotechnics are expensive & dangerous

• Goal is an impressive ( realistic ) fireball

• ( Accurate ) damage effects are of little or no consequence

• This work is based upon suspended particle explosions, a.k.a. dust explosions

Explosion Types

• Mechanical - Rupture of a high pressure tank

• Dust Explosions - Typically grain or coal

• Vapor Cloud Explosions - E.g. Flixborough England, where 30 tons of cyclohexane leveled the plant and killed 28 people.

• BLEVE - Boiling Liquid Expanding Vapor Explosion

Properties of Dust Explosions• Dust particles must be below a certain size.

• Particle loading in air must be within certain limits, and relatively uniform.

• ( Unentrained dust is typically non flammable. )

• Primary explosions often stir up additional dust, leading to (more powerful) secondary explosions.

• A series of grain silo explosions killed 35 people in Westsego near New Orleans in 1977.

Damage Produced by Overpressurepsig Damage

0.5-1 Windows Shattered

1.0 Houses uninhabitable

2-3 Non-reinforced concrete walls shattered

5 Wooden utility poles snapped

5-7 Nearly complete destruction of homes

10 Probable total destruction of buildings

Simulation Method

• Based on Physics, Thermodynamics, etc.

• Four major components:

1. Gas Model - Air and Combustion Products

2. Particulate Model - Heat & Mass Transfer

3. Detonation, Dispersal, and Ignition

4. Interaction and Combustion

Gas Model• Modeled as an incompressible inviscid fluid,

in a rectangular 3D grid.

• Euler Equation ( Navier Stokes w/o viscosity):

• Modified Poisson’s Equation:

• Temperature:

( ) / /u u u p f (1)

2 ( )p ut

(3)

4

2

max

1( ) a

r ka v

T TT u T c c T H

T T c

(4)

Particulate Model

• Particles include solid particulate fuel & soot

• Properties include position, mass, velocity, temperature, thermal mass, volume, & type.

• Governing equations:

• a.k.a. :

/x f m / mY H c(5)

f ma pQ mc T

Detonation, Dispersal, Ignition• Pressure front from a detonation is imposed by

a divergence function radiating from a point:

Fluid / Particulate Interaction

• Momentum transfer ( drag on particles ):

• Heat transfer to particle from fluid:

• When a particle’s temperature rises above its ignition point, it commences combustion . . .

2 ( )df r u x u x (6)

2 ( )hH r T Y (7)

Combustion

• Particle Heat + Gas + Soot

• Heat:

• Gas:

• Soot:

hH b z (8)

1gb zV

(9)

ss b z (10)

Rendering

• Fuel and soot particles are rendered directly.

• Lighting comes from the environment, and

• Particles glow if sufficiently hot.

• Light emission is based on black body radiation.

• Deep shadows ( Lukovic & Veach 2000 ) used.

• Light scattering by particles also employed.

Single Unconfined Explosion

Single Explosion at a Wall

Single Confined Explosions

Comparison With Experiment

Multiple Detonations

Flame Throwers

References

• Feldman, Bryan E., James F. O’Brien, and Okan Arikan, “Animating Suspended Particle Explosions”, SIGGRAPH 2003, pp. 708-715.

• Crowl, Daniel A. and Joseph F. Louvar, “Chemical Process Safety: Fundamentals with Applications”, Prentice Hall, 1990, ISBN 0-13-129701-5.

Animating SuspendedParticle Explosions

Presented at SIGGRAPH 2003 by

Bryan E. Feldman

James F. O’Brien

Okan Arikan

University of California, Berkeley

Reviewed for CS 527 by

John T. Bell