Browsing by Author "Li, Chenfeng"

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    A Divergence-free Mixture Model for Multiphase Fluids
    (The Eurographics Association and John Wiley & Sons Ltd., 2020) Jiang, Yuntao; Li, Chenfeng; Deng, Shujie; Hu, Shi-Min; Bender, Jan and Popa, Tiberiu
    We present a novel divergence free mixture model for multiphase flows and the related fluid-solid coupling. The new mixture model is built upon a volume-weighted mixture velocity so that the divergence free condition is satisfied for miscible and immiscible multiphase fluids. The proposed mixture velocity can be solved efficiently by adapted single phase incompressible solvers, allowing for larger time steps and smaller volume deviations. Besides, the drift velocity formulation is corrected to ensure mass conservation during the simulation. The new approach increases the accuracy of multiphase fluid simulation by several orders. The capability of the new divergence-free mixture model is demonstrated by simulating different multiphase flow phenomena including mixing and unmixing of multiple fluids, fluid-solid coupling involving deformable solids and granular materials.
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    A Rigging-Skinning Scheme to Control Fluid Simulation
    (The Eurographics Association and John Wiley & Sons Ltd., 2019) Lu, Jia-Ming; Chen, Xiao-Song; Yan, Xiao; Li, Chen-Feng; Lin, Ming; Hu, Shi-Min; Lee, Jehee and Theobalt, Christian and Wetzstein, Gordon
    Inspired by skeletal animation, a novel rigging-skinning flow control scheme is proposed to animate fluids intuitively and efficiently. The new animation pipeline creates fluid animation via two steps: fluid rigging and fluid skinning. The fluid rig is defined by a point cloud with rigid-body movement and incompressible deformation, whose time series can be intuitively specified by a rigid body motion and a constrained free-form deformation, respectively. The fluid skin generates plausible fluid flows by virtually fluidizing the point-cloud fluid rig with adjustable zero- and first-order flow features and at fixed computational cost. Fluid rigging allows the animator to conveniently specify the desired low-frequency flow motion through intuitive manipulations of a point cloud, while fluid skinning truthfully and efficiently converts the motion specified on the fluid rig into plausible flows of the animation fluid, with adjustable fine-scale effects. Besides being intuitive, the rigging-skinning scheme for fluid animation is robust and highly efficient, avoiding completely iterative trials or time-consuming nonlinear optimization. It is also versatile, supporting both particle- and grid- based fluid solvers. A series of examples including liquid, gas and mixed scenes are presented to demonstrate the performance of the new animation pipeline.