SIGGRAPH 2016: Generalized Non-Reflecting Boundaries for Fluid Re-Simulation

Title: Generalized Non-Reflecting Boundaries for Fluid Re-Simulation
Publication: SIGGRAPH 2016
WWW: http://visualcomputing.ist.ac.at/publications/2016/GNRBfFRS/

Authors:
Morten Bojsen-Hansen (IST Austria)
Chris Wojtan (IST Austria)

Abstract: When aiming to seamlessly integrate a fluid simulation into a larger scenario (like an open ocean), careful attention must be paid to boundary conditions. In particular, one must implement special "non-reflecting" boundary conditions, which dissipate out-going waves as they exit the simulation. Unfortunately, the state of the art in non-reflecting boundary conditions (perfectly-matched layers, or PMLs) only permits trivially simple inflow/outflow conditions, so there is no reliable way to integrate a fluid simulation into a more complicated environment like a stormy ocean or a turbulent river.

This paper introduces the first method for combining non-reflecting boundary conditions based on PMLs with inflow/outflow boundary conditions that vary arbitrarily throughout space and time. Our algorithm is a generalization of state-of-the-art mean-flow boundary conditions in the computational fluid dynamics literature, and it allows for seamless integration of a fluid simulation into much more complicated environments. Our method also opens the door for previously-unseen post-process effects like retroactively changing the location of solid obstacles, and locally increasing the visual detail of a pre-existing simulation.