Fluid Simulation of China Ink and Water that Enables Control of The Diffusion Effect

Abstract

This paper proposes a simulation method that can enable the user to control the movements of China ink being dispersed in water. In the proposed method, the fluid calculations for China ink dispersing in water were made into a model with a grid base using a 2-dimensional incompressible fluid equation, then it was expanded into a 3-dimensional fluid field using the Kolmogorov spectrum. Furthermore, when an animator wishes to express desired shapes using the diffusion phenomenon of China ink, he/she prepares beforehand the shapes for which he/she wants to control the diffusion phenomenon (a process called “targeting”) and defines them in the interior of the 3-dimensional fluid field. In the 3-dimensional fluid field where the target shape is defined, a particle equivalent in size to one voxel is moved into the target shape according to the fluid body field, and a decision is made about collision between the particle and the target shape. In other words, the 3-dimensional fluid field is renewed according to the movement path of the particle. This enables the formation of new 3-dimensional fluid fields inside the target shape and allows the animator to express the diffusion phenomenon of China ink inside the desired shape.