Representation of Bubbles in High Viscosity Fluids for CG

<p>To depict liquid realistically in computer graphics (CG) works, it is necessary to represent bubbles in the liquid. In conventional studies, liquid and gas particles have been utilized to represent bubbles in a liquid. On the other hand, the gas particles increase computational complexity. Additionally, the conventional fluid simulations can not utilize an implicit method to calculate the flow of liquid with high viscosity. This study proposes a simulation method to represent bubbles in liquid with various viscosity without gas particles. To calculate bubbles, we utilize the conservation of the mass of bubbles. For this purpose, we apply pressure calculated from the bubble density as the pressure boundary condition at the bubble surface to the Navier-Stokes equation. By assuming that the sum of vertical velocity to the surface at the bubble is zero, the volume change of the bubble can be minimized. The simulation method does not require gas particles because the two conditions conserve the mass and the volume of a gas. The proposed model can be incorporated into the material point method, which can represent liquid with various viscosity in a short time. Owing to the mentioned characteristics, the proposed model can realistically represent bubbles in a liquid such as water or honey and contribute to improving the quality of CG works.</p>