Inverse Modeling of Incompressible Gas Flow in Subspace

This paper advocates a novel method for modeling physically realistic flow from captured incompressible gas sequence via modal analysis in frequency-constrained subspace. Our analytical tool is uniquely founded upon Empirical Mode Decomposition (EMD) and modal reduction for fluids, which are seamlessly integrated towards a powerful, style-controllable flow modeling approach. We first extend EMD, which is capable of processing 1D time series but had shown inadequacies for 3D graphics earlier, to fit gas flows in 3D. Next, frequency components from EMD are adopted as candidate vectors for bases of modal reduction. The prerequisite parameters of the Navier-Stokes equations are then optimized to inversely model the physically realistic flow in the frequency-constrained subspace. The estimated parameters can be utilized for re-simulation, or be altered toward fluid editing. Our novel inverse-modeling technique produces real-time gas sequences after precomputation, and is convenient to couple with other methods for visual enhancement and/or special visual effects. We integrate our new modeling tool with a state-of-the-art fluid capturing approach, forming a complete pipeline from real-world fluid to flow re-simulation and editing for various graphics applications.