nomenon
we often observe. In this paper, we present an energybased
Lagrangian method that expands the capability of existing
multiple-fluid methods to handle various phenomena, such as
extraction, partial dissolution, etc. Based on our user-adjusted
Helmholtz free energy functions, the simulated fluid evolves from
high-energy states to low-energy states, allowing flexible capture of
various mixing and unmixing processes. We also extend the original
Cahn-Hilliard equation to be better able to simulate complex
fluid-fluid interaction and rich visual phenomena such as motionrelated
mixing and position based pattern. Our approach is easily
integrated with existing state-of-the-art smooth particle hydrodynamic
(SPH) solvers and can be further implemented on top of the
position based dynamics (PBD) method, improving the stability and
incompressibility of the fluid during Lagrangian simulation under
large time steps. Performance analysis shows that our method is at
least 4 times faster than the state-of-the-art multiple-fluid method.
Examples are provided to demonstrate the new capability and effectiveness
of our approach.