An Implicitly Stable Mixture Model for Dynamic Multi-fluid Simulations
Problem
Particle-based simulations have become increasingly popular in real-time applications due to their efficiency and adaptability, especially for generating highly dynamic fluid effects. However, the swift and stable simulation of interactions among distinct fluids poses challenges for current mixture model techniques. When using a single-mixture flow field to represent all fluid phases, numerical discontinuities in phase fields can lead to significant losses of dynamic effects and unstable conservation of mass and momentum.
Solution
To tackle these issues, we present an advanced implicit mixture model for smoothed particle hydrodynamics. Instead of using an explicit mixture field for all dynamic computations and phase transfers between particles, we calculate phase momentum sources from the mixture model to derive explicit and continuous velocity phase fields. We then implicitly obtain the mixture field using a phase-mixture momentum-mapping mechanism that ensures conservation of incompress- ibility, mass, and momentum.
We also propose a mixture viscosity model and establish viscous effects between the mixture and individual fluid phases to avoid instability under extreme inertia conditions.
Results
The snapshots below show stills from a complex fluid simulation achieved with our model. Note the subtle diffusion effects between the different phases.
The video below shows extensive results of what our simulation model is capable of.
Code
The code of our simulation model is publicly available here.
Reference
Y. Xu, X. Wang, J. Wang, C. Song, T. Wang, Y. Zhang, J. Chang, J. Zhang, J. Kosinka, A. Telea, X. Ban (2023) An Implicitly Stable Mixture Model for Dynamic Multi-fluid Simulations. Proc. SIGGRAPH Asia.