Position Based Multi- Fluids Tao Yang 2014/10/24.

Position Based Multi-Fluids

Tao Yang2014/10/24

Traditional Particle/Vertex MethodPosition->density & pressure->force->acceleration->position & velocity

• Based on Newton’s second law• Limited step time• Unstable(overshooting)• Uncontrollable

SPH/Particle level set/FLIP

Force Based Method

Position Based Dynamics

• A serial of constraints• Control position directly• Stable & controllable

MULLER, M., H EIDELBERGER, B., H ENNIX, M., AND RATCLIFF, J. 2007. Position based dynamics. J. Vis. Comun. Image Represent. 18, 2 (Apr.), 109–118.

Position Based Dynamics

Constraint types:

• Distance(clothing)• Shape(rigids, plastics)• Density(fluids)->self-adaptive incompressible• Volume(inflatables)• Contact(non-penetration, friction)

Position Based Fluids

MACKLIN, M., AND MULLER, M. 2013. Position based fluids. ACM Trans. Graph. 32, 4 (July), 104:1–104:12.

Multi-Fluid Simulation

• WCSPH + A mixture model • Miscible & immiscible• Chemical reaction• Unmixing

Main drawbacks: Compressible + speed + boundary

Bo Ren et al. 2014. Multiple-fluid SPH Simulation Using a Mixture Model. ACM Trans. Graph

Project Idea

Why not combine two of them?

• Position Based Dynamics + Multi-Fluid Simulation = Position Based Multi-Fluids

• Immiscible position based multi-fluids

Miles Macklin et al. 2014. Unified Particle Physics for Real-Time Applications. ACM SIGGRAPH

Heat Transport and Phase Change• MPM(material point method)• Heat transport• Phase Change(melting, solidifying…)

Alexey Stomakhin et al.2014. Augmented MPM for phase-change and varied materials. ACM Trans. Graph

Schedule

• Implement Position Based Fluids(done!)• Implement immiscible Position Based Multi-Fluids(done!)• Implement Multi-Fluids simulation(having codes)• Theory deduction(always)• ….