Chris Wojtan, Georgia Tech: Animating Physical Phenomena with Embedded Surface Meshes
Andreas Söderström, Linköping University: Memory Efficient Methods for Eulerian Free Surface Fluid Animation
Category: Fluids
Fast Particle-Based Visual Simulation of Melting Ice
The visual simulation of natural phenomena has been widely studied. Although several methods have been proposed to simulate melting, the flows of meltwater drops on the surfaces of objects are not taken into account. In this paper, we propose a particle-based method for the simulation of the melting and freezing of ice objects and the interactions between ice and fluids. To simulate the flow of meltwater on ice and the formation of water droplets, a simple interfacial tension is proposed, which can be easily incorporated into common particle-based simulation methods such as Smoothed Particle Hydrodynamics. The computations of heat transfer, the phase transition between ice and water, the interactions between ice and fluids, and the separation of ice due to melting are further accelerated by implementing our method using CUDA. We demonstrate our simulation and rendering method for depicting melting ice at interactive frame-rates.
Interactive SPH Simulation and Rendering on the GPU
In this paper we introduce a novel parallel and interactive SPH simulation and rendering method on the GPU using CUDA which allows for high quality visualization. The crucial particle neighborhood search is based onZ-indexing and parallel sorting which eliminates GPU memory overhead due to grid or hierarchical data structures. Furthermore, it overcomes limitations imposed by shading languages allowing it to be very flexible and approaching the practical limits of modern graphics hardware. For visualizing the SPH simulation we introduce a new rendering pipeline. In the first step, all surface particles are efficiently extracted from the SPH particle cloud exploiting the simulation data. Subsequently, a partial and therefore fast distance field volume is rasterized from the surface particles. In the last step, the distance field volume is directly rendered using state-of-the-art GPU raycasting. This rendering pipeline allows for high quality visualization at very high frame rates.
Vector Fluid: A Vector Graphics Depiction of Free Surface Flow
We present a simple technique for creating fluid silhouettes described with vector graphics, which we call “Vector Fluid.” In our system, a solid region in the fluid is represented as a closed contour and advected by fluid flow to form a curly and clear shape similar to marbling or sumi-nagashi. The fundamental principle behind our method is that contours of solid regions should not collide. This means that if the initial shape of the region is a concave polygon, that shape should maintain its topology so that it can be rendered as a regular concave polygon, no matter how irregularly the contour is distorted by advection. In contrast to other techniques, our approach explicitly neglects topology changes to track surfaces in a trade off of computational cost and complexity. We also introduce an adaptive contour sampling technique to reduce this extra cost. We explore specific examples in 2D for art oriented usage and show applications and robustness of our method to exhibit organic fluid components. We also demonstrate how to port our entire algorithm onto a GPU to boost interactive performance for complex scenes.
Vector Fluid: A Vector Graphics Depiction of Free Surface Flow
Detail-Preserving Fully Eulerian Interface Tracking Framework
This paper introduces a fully-Eulerian interface tracking framework that preserves the fine details of liquids. Unlike existing Eulerian methods, the proposed framework shows good mass conservation even though it does not employ conventional Lagrangian elements. In addition, it handles complex merging and splitting of interfaces robustly due to the implicit representation. To model the interface more accurately, a high order polynomial reconstruction of the signed distance function is utilized based on a number of sub-grid quadrature points. By combining this accurate polynomial representation with a high-order re-initialization method, the proposed framework preserves the detailed structures of the interface. Moreover, the method is simple to implement, unconditionally stable, and is suitable for parallel computing environments.
Detail-Preserving Fully Eulerian Interface Tracking Framework
Free-Flowing Granular Material with Two-Way Solid Coupling
We present a novel continuum-based model that enables efficient simulation of granular materials. Our approach fully solves the internal pressure and frictional stresses in a granular material, thereby allows visually noticeable behaviors of granular materials to be reproduced, including freely dispersing splashes without cohesion, and a global coupling between friction and pressure. The full treatment of internal forces in the material also enables two-way interaction with solid bodies. Our method achieves these results at only a very small fraction of computational costs of the comparable particle-based models for granular flows.
Boundary handling and adaptive time-stepping for PCISPH
We present a novel boundary handling scheme for incompressible fluids based on Smoothed Particle Hydro-dynamics (SPH). In combination with the predictive-corrective incompressible SPH (PCISPH) method, the boundary handling scheme allows for larger time steps compared to existing solutions. Furthermore, an adaptive time-stepping approach is proposed. The approach automatically estimates appropriate time steps independent of the scenario. Due to its adaptivity, the overall computation time of dynamic scenarios is significantly reduced compared to simulations with constant time steps.
A Parallel SPH Implementation on Multi-core CPUs
This paper presents a parallel framework for simulating fluids with the Smoothed Particle Hydrodynamics (SPH) method. For low computational costs per simulation step, efficient parallel neighborhood queries are proposed and compared. To further minimize the computing time for entire simulation sequences, strategies for maximizing the time step and the respective consequences for parallel implementations are investigated. The presented experiments illustrate that the parallel framework can efficiently compute large numbers of time steps for large scenarios. In the context of neighborhood queries, the paper presents optimizations for two efficient instances of uniform grids, i. e. spatial hashing and index sort. For implementations on parallel architectures with shared memory, the paper discusses techniques with improved cache-hit rate and reduced memory transfer. The performance of the parallel implementations of both optimized data structures is compared. The proposed solutions focus on systems with multiple CPUs. Benefits and challenges of potential GPU implementations are only briefly discussed.
Scalable Fluid Simulation using Anisotropic Turbulence Particles
It is usually difficult to resolve the fine details of turbulent flows, especially when targeting real-time applications. We present a novel, scalable turbulence method that uses a realistic energy model and an efficient particle representation that allows for the accurate and robust simulation of small-scale detail. We compute transport of turbulent energy using a complete two-equation k–e model with accurate production terms that allows us to capture anisotropic turbulence effects, which integrate smoothly into the base flow. We only require a very low grid resolution to resolve the underlying base flow. As we offload complexity from the fluid solver to the particle system, we can control the detail of the simulation easily by adjusting the number of particles, without changing the large scale behavior. In addition, no computations are wasted on areas that are not visible. We demonstrate that due to the design of our algorithm it is highly suitable for massively parallel architectures, and is able to generate detailed turbulent simulations with millions of particles at high framerates.
Scalable Fluid Simulation using Anisotropic Turbulence Particles
Multi-Phase Fluid Simulation Using Regional Level Sets
We address the problem of Multi-Phase (or Many-Phase) Fluid simulations. We propose to use the regional level set (RLS) that can handle a large number of regions and materials, and hence, is appropriate for simulations of many immiscible materials. Towards this goal, we improve the interpolation of the RLS, and develop the regional level set graph (RLSG), which registers connected components and their contacts, and tracks their properties such as region volumes, film life times, and film material types, as regions evolve, merge, split, or are squeezed into films. Using RLSG’s tracking feature, we generate particles from tiny regions or rupturing films.