Synthetic Turbulence using Artificial Boundary Layers

Abstract: Turbulent vortices in fluid flows are crucial for a visually interesting appearance. Although there has been a significant amount of work on turbulence in graphics recently, these algorithms rely on the underlying simulation to resolve the flow around objects. We build upon work from classical fluid mechanics to design an algorithm that allows us to accurately precompute the turbulence being generated around an object immersed in a flow. This is made possible by separating the flow into a mean and a fluctuating component, and relying on universal laws describing the flow near a wall. We precompute the turbulence characteristics around an object, and inject corresponding vorticity during a fluid simulation run, giving regions of confined vorticity. Then, a turbulence model is used to identify areas where this vorticity will transition into actual turbulence. We sample these regions with vortex particles, and simulate the further dynamics of the vortices based on these particles. We will show how our method complements previous work on synthetic turbulence, and yields physically plausible results. In addition, we demonstrate that our method can efficiently compute turbulent flows around a variety of objects including cars, whisks, as well as boulders in a river flow. We can even apply our model to precomputed static flow fields, yielding turbulent dynamics without a costly simulation.