I am a doctoral student in computer science at Columbia University, advised by Professor Eitan Grinspun. My research involves physically based animation techniques, with a particular focus on the modeling and simulation of fluid phenomena.

I received my B.S. degree at Peking University in 2007, and M.S. degree at Columbia University in 2012.


Multimaterial Mesh-Based Surface Tracking

Fang Da, Christopher Batty, Eitan Grinspun
ACM Transaction on Graphics (Proceedings of SIGGRAPH 2014).

We present a triangle mesh-based technique for tracking the evolution of three-dimensional multimaterial interfaces undergoing complex deformations. It is the first non-manifold triangle mesh tracking method to simultaneously maintain intersection-free meshes and support the proposed broad set of multimaterial remeshing and topological operations. We represent the interface as a non-manifold triangle mesh with material labels assigned to each half-face to distinguish volumetric regions. Starting from proposed application-dependent vertex velocities, we deform the mesh, seeking a non-intersecting, watertight solution. This goal necessitates development of various collision-safe, label-aware non-manifold mesh operations: multimaterial mesh improvement; T1 and T2 processes, topological transitions arising in foam dynamics and multi-phase flows; and multimaterial merging, in which a new interface is created between colliding materials. We demonstrate the robustness and effectiveness of our approach on a range of scenarios including geometric flows and multiphase fluid animation.
[PDF] [Bib] [Project][MP4][C++ Code]

Coiling of Elastic Rods on Rigid Substrates

Khalid Jawed, Fang Da (Joint first author), Jungseock Joo, Eitan Grinspun, Pedro Reis
Proceedings of the National Academy of Sciences. 2014.

We investigate the deployment of a thin elastic rod onto a rigid substrate and study the resulting coiling patterns. In our approach, we combine precision model experiments, scaling analyses, and computer simulations toward developing predictive understanding of the coiling process. Both cases of deposition onto static and moving substrates are considered. We construct phase diagrams for the possible coiling patterns and characterize them as a function of the geometric and material properties of the rod, as well as the height and relative speeds of deployment. The modes selected and their characteristic length scales are found to arise from a complex interplay between gravitational, bending, and twisting energies of the rod, coupled to the geometric nonlinearities intrinsic to the large deformations. We give particular emphasis to the first sinusoidal mode of instability, which we find to be consistent with a Hopf bifurcation, and analyze the meandering wavelength and amplitude. Throughout, we systematically vary natural curvature of the rod as a control parameter, which has a qualitative and quantitative effect on the pattern formation, above a critical value that we determine. The universality conferred by the prominent role of geometry in the deformation modes of the rod suggests using the gained understanding as design guidelines, in the original applications that motivated the study. [PDF] [Bib] [Project][C++ Code]