| Summary: | Ubiquitous and captivating, fluid—gaseous and liquid—motion is often desired in computer
animation. For example, rives, lakes, and clouds enhance flights simulations. Realizing realistic
fluid behaviour, however, can be difficult and laborious using traditional computer animation
methods. Ad hoc kinematic models of fluid motion have been presented to facilitate the animation
of fluids, but it is not clear how to extend or integrate these models to describe more
general fluid motion. Simple dynamic models have been presented, but it is difficult to control
the dynamic simulation to achieve the desired effect. To address this problem, a simple,
hydrodynamically-based framework for realistically integrating models of fluid flow for computer
animation purposes is presented. This framework is based on the continuity equation for
incompressible flow, and allows flow fields to be linearly combined, regardless of whether they
are interactively modeled or computed by dynamic simulation. Novel interactive flow field modeling
methods are introduced to allow the animator to manipulate spline curves that correspond
to streamlines in the flow field. The spline-based flow fields can be computed at interactive
speed on standard graphics workstations. Many dynamic simulations produce flow fields that
satisfy the continuity equation, and these can be linearly combined with the modeled flow field
to define a mean flow field which is sampled at the nodes of a lattice. Turbulence is modeled by
advecting stochastic distributions of models of vortex flow with the mean flow, allowing infinite
resolution for small-scale complexity. Geometric models are advected using the final resulting
flow field. A simple animation system incorporating the interactive flow modeling methods
was implemented and shows this approach to be a promising and easily extendable method of
realistically animating fluids. === Science, Faculty of === Computer Science, Department of === Graduate
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