Animating Explosions

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Animating Explosions

• Abhinav Golas
• Akram Khan
• Under the guidance of Prof. Kalra Prof. Kumar

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Outline

• The problem
• How weve split the problem
• Current progress
• Some comparison

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The problem

• Animating explosions Navier Stokes
• Modeling the pressure wave
• Issues
• Large quantities
• Large spatial temporal derivatives
• Inherent shocks (speed of sound)
• Large bulk transfer

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How weve split the problem

• Abhinav
• Navier Stokes modeling
• Focus on seeing impact of viscosity on simulation
  in different media
• Models for different solver components applying
  known methods for incompressible flows to problem

• Akram
• Euler equation modeling inviscid Navier Stokes
• Mostly first derivatives scope for linear
  algebra based solvers
• Focus will be on modeling as sparse linear systems

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Current Progress

• Our implementation
• Ready
• Some methods for larger timestep simulation ready
• Original paper implementation (Animating
  Explosions Yngve et al, SIGGRAPH 2000)
• 2D version ready some parameter tuning required
• Rendering
• Renderman based particle systems renderer
• Uses order of 100000 particles

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Some comparison

• Original implementation
• 0.1 ms timestep for simple blast case
• Our implementation
• 1 ms timestep for simple blast case using
  multistep advection
• 5 ms timestep for same case also done.

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Modifications made

• Staggered grid (vs. centralized grid)
• Better accuracy of spatial derivatives
• Semi-lagrangian based multi-step advecton(vs.
  donor acceptor method)
• Much more stable guarantee of outputltinput
  (but slight dissipation)
• Allows for larger timesteps
• Step 1ms 5ms
• Frame at 15ms

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Future work

• Complete comparison with earlier implementation
• Improve methods to allow larger timesteps
• Improve rendering
• Experiment with ENO methods (CFD)
• Develop solid interaction and fracturing models

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Thanks