Control of physics-based fluid animation using a velocity-matching method

Fluid animation remains one of the most challenging problems in computer graphics. Research on methods using physics-based simulation for animation has recently increased since this method has the capability of producing realistic fluid behavior. However, the primary drawback to using a simulation method is control of the resulting flow field because it is computationally expensive and highly nonlinear.; The main goal of this research is to help users produce physically realistic fluid effects along a NURBS curve that can be specified directly or derived from an image or video. A linear-feedback velocity matching method is used to control the fluid flow. A physically realistic smoke flow along a user-specified path is generated by first procedurally producing a target velocity field, and then matching the velocity field obtained from a three-dimensional flow simulation with the target velocity field. The target velocity field can include various effects such as the small scale swirling motion characteristic of turbulent flows. The swirling motion is achieved by incorporating a vortex particle method into the linear feedback loop. The method is flexible in that any procedurally-generated target velocity field may be integrated with the fluid simulation. The efficacy of this approach is demonstrated by generating several three-dimensional flow animations for complex fluid paths, two-dimensional artistic fluid effects, and realistic tornado animations.