Animation tools for interactive flow visualization

The authors have built a new graphics environment for essentially real-time visualization of the results of numerical simulations of fluid mechanics. Starting from a precomputed discrete set of time-dependent flow quantities, such as velocity and density, the user may interactively examine the data on a frame buffer using animated flow visualization diagnostics that mimic those in the experimental laboratory. The graphics environment accepts data written in a general format and can handle a wide variety of flow geometries. Images are updated at 9 frame/s, providing an effective way to study the solution, analyze fluid flow mechanisms, and compare numerical results with experiment. The authors have used this environment to analyze data produced from numerical simulations of viscous, incompressible, laminar, and turbulent flow. They have studied two-dimensional flow over a backward-facing step and in a closed square computed using Chorin's Random Vortex Method. The graphics environments can be used to isolate and identify a variety of physical flow phenomena, such as eddy formation and merger, propagation and decay, horseshoe vortices, mixing and intertwining of fluid structures, and pairing of counteroscillatory vortical structures.