84 research outputs found
Physical simulation of wood combustion by using particle system
Ankara : The Department of Computer Engineering and the Institute of Engineering and Science of Bilkent University, 2010.Thesis (Master's) -- Bilkent University, 2010.Includes bibliographical references leaves 50-54.In computer graphics, the most challenging problem is modeling natural phenomena
such as water, re, smoke etc. The reason behind this challenge is the
structural complexity, as the simulation of natural phenomena depends on some
physical equations that are di cult to implement and model. In complex physically
based simulations, it is required to keep track of several properties of the
object that participates in the simulation. These properties can change and their
alteration may a ect other physical and thermal properties of object. As one
of natural phenomena, burning wood has various properties such as combustion
reaction, heat transfer, heat distribution, fuel consumption and object shape in
which change in one during the duration of simulation alters the e ects of some
other properties.
There have been several models for animating and modeling re phenomena.
The problem with most of the existing studies related to re modeling is that
decomposition of the burning solid is not mentioned, instead solids are treated
only as fuel source.
In this thesis, we represent a physically based simulation of a particle based
method for decomposition of burning wood and combustion process. In our work,
besides being a fuel source, physical and thermal a ects of combustion process
over wood has been observed. A particle based system has been modelled in
order to simulate the decomposition of a wood object depending on internal and
external properties and their interactions and the motion of the spreading re
according to combustion process.Gürcüoğlu, GizemM.S
Real-time Physics Based Simulation for 3D Computer Graphics
Restoration of realistic animation is a critical part in the area of computer graphics. The goal of this sort of simulation is to imitate the behavior of the transformation in real life to the greatest extent. Physics-based simulation provides a solid background and proficient theories that can be applied in the simulation. In this dissertation, I will present real-time simulations which are physics-based in the area of terrain deformation and ship oscillations.
When ground vehicles navigate on soft terrains such as sand, snow and mud, they often leave distinctive tracks. The realistic simulation of such vehicle-terrain interaction is important for ground based visual simulations and many video games. However, the existing research in terrain deformation has not addressed this issue effectively. In this dissertation, I present a new terrain deformation algorithm for simulating vehicle-terrain interaction in real time. The algorithm is based on the classic terramechanics theories, and calculates terrain deformation according to the vehicle load, velocity, tire size, and soil concentration. As a result, this algorithm can simulate different vehicle tracks on different types of terrains with different vehicle properties. I demonstrate my algorithm by vehicle tracks on soft terrain.
In the field of ship oscillation simulation, I propose a new method for simulating ship motions in waves. Although there have been plenty of previous work on physics based fluid-solid simulation, most of these methods are not suitable for real-time applications. In particular, few methods are designed specifically for simulating ship motion in waves. My method is based on physics theories of ship motion, but with necessary simplifications to ensure real-time performance. My results show that this method is well suited to simulate sophisticated ship motions in real time applications
Interactive simulation of fire, burn and decomposition
This work presents an approach to effectively integrate into one unified modular
fire simulation framework the major processes related to fire, namely: a burning
process, chemical combustion, heat distribution, decomposition and deformation of
burning solids, and rigid body simulation of the residue. Simulators for every stage
are described, and the modular structure enables switching to different simulators if
more accuracy or more interactivity is desired. A “Stable Fluids” based three gas
system is used to model the combustion process, and the heat generated during the
combustion is used to drive the flow of the hot air. Objects, if exposed to enough
heat, ignite and start burning. The decomposition of the burning object is modeled as
a level set method, driven by the pyrolysis process, where the burning object releases
combustible gases. Secondary deformation effects, such as bending burning matches
and crumpling burning paper, are modeled as a proxy based deformation.
Physically based simulation, done at interactive rates, enables the user to ef-
ficiently test different setups, as well as interact and change the conditions during
the simulation. The graphics card is used to generate additional frames for real-time
visualization.
This work further proposes a method for controlling and directing high resolution
simulations. An interactive coarse resolution simulation is provided to the user as a “preview” to control and achieve the desired simulation behavior. A higher resolution
“final” simulation that creates all the fine scale behavior is matched to the preview
simulation such that the preview and final simulations behave in a similar manner.
In this dissertation, we highlighted a gap within the CG community for the
simulation of fire. There has not previously been a physically based yet interactive
simulation for fire. This dissertation describes a unified simulation framework for
physically based simulation of fire and burning. Our results show that our implementation
can model fire, objects catching fire, burning objects, decomposition of
burning objects, and additional secondary deformations. The results are plausible
even at interactive frame rates, and controllable
Recommended from our members
Real-time Rendering of Burning Objects in Video Games
In recent years there has been growing interest in limitless realism in computer graphics applications. Among those, my foremost concentration falls into the complex physical simulations and modeling with diverse applications for the gaming industry. Different simulations have been virtually successful by replicating the details of physical process. As a result, some were strong enough to lure the user into believable virtual worlds that could destroy any sense of attendance. In this research, I focus on fire simulations and its deformation process towards various virtual objects. In most game engines model loading takes place at the beginning of the game or when the game is transitioning between levels. Game models are stored in large data structures. Since changing or adjusting a large data structure while the game is proceeding may adversely affect the performance of the game. Therefore, developers may choose to avoid procedural simulations to save resources and avoid interruptions on performance. I introduce a process to implement a real-time model deformation while maintaining performance. It is a challenging task to achieve high quality simulation while utilizing minimum resources to represent multiple events in timely manner. Especially in video games, this overwhelming criterion would be robust enough to sustain the engaging player's willing suspension of disbelief. I have implemented and tested my method on a relatively modest GPU using CUDA. My experiments conclude this method gives a believable visual effect while using small fraction of CPU and GPU resources
Computational homogenisation of thermomechanical problems
The thesis at hand deals with the modelling of heat input and mass deposition during thermal spraying and especially with the capturing of the effective material behaviour of microstructures under consideration of inelasticity in the framework of thermo-mechanical continua. The heat input during thermal spraying is modelled by means of convective heat transfer as well as radiation in the framework of a non-linear rigid heat conductor which is implemented into a finite element programme. This model is subsequently extended in order to capture mass deposition via hot particles by a novel thermodynamically consistent ansatz. As this work proceeds, the main emphasis of this thesis is on the development of a thermo-mechanically coupled two-scale finite element programme. Here, the effective material behaviour of underlying microstructures is directly used in the solution of boundary value problems at the upper scale of application by means of numerical homogenisation. The implementation is carried out in the framework of small as well as finite deformations. In both cases, a thermo-viscoplastic material model is applied in order to exemplarily represent non-linear inelastic material behaviour. Furthermore, novel boundary conditions are elaborated for the solution of thermo-mechanically coupled boundary values problems at the scale of the underlying microstructure. The capabilities of the developed finite element frameworks as well as of the novel methods included therein are shown by means of descriptive numerical simulations
Animating Unpredictable Effects
Uncanny computer-generated animations of splashing waves, billowing smoke clouds, and characters’ flowing hair have become a ubiquitous presence on screens of all types since the 1980s. This Open Access book charts the history of these digital moving images and the software tools that make them. Unpredictable Visual Effects uncovers an institutional and industrial history that saw media industries conducting more private R&D as Cold War federal funding began to wane in the late 1980s. In this context studios and media software companies took concepts used for studying and managing unpredictable systems like markets, weather, and fluids and turned them into tools for animation. Unpredictable Visual Effects theorizes how these animations are part of a paradigm of control evident across society, while at the same time exploring what they can teach us about the relationship between making and knowing
Multiscale methods for fabrication design
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 135-146).Modern manufacturing technologies such as 3D printing enable the fabrication of objects with extraordinary complexity. Arranging materials to form functional structures can achieve a much wider range of physical properties than in the constituent materials. Many applications have been demonstrated in the fields of mechanics, acoustics, optics, and electromagnetics. Unfortunately, it is difficult to design objects manually in the large combinatorial space of possible designs. Computational design algorithms have been developed to automatically design objects with specified physical properties. However, many types of physical properties are still very challenging to optimize because predictive and efficient simulations are not available for problems such as high-resolution non-linear elasticity or dynamics with friction and impact. For simpler problems such as linear elasticity, where accurate simulation is available, the simulation resolution handled by desktop workstations is still orders of magnitudes below available printing resolutions. We propose to speed up simulation and inverse design process of fabricable objects by using multiscale methods. Our method computes coarse-scale simulation meshes with data-drive material models. It improves the simulation efficiency while preserving the characteristic deformation and motion of elastic objects. The first step in our method is to construct a library of microstructures with their material properties such as Young's modulus and Poisson's ratio. The range of achievable material properties is called the material property gamut. We developed efficient sampling method to compute the gamut by focusing on finding samples near and outside the currently sampled gamut. Next, with a pre-computed gamut, functional objects can be simulated and designed using microstructures instead of the base materials. This allows us to simulate and optimize complex objects at a much coarser scale to improve simulation efficiency. The speed improvement leads to designs with as many as a trillion voxels to match printer resolutions. It also enables computational design of dynamic properties that can be faithfully reproduced in reality. In addition to efficient design optimization, the gamut representation of the microstructure envelope provides a way to discover templates of microstructures with extremal physical properties. In contrast to work where such templates are constructed by hand, our work enables the first computational method to automatically discovery microstructure templates that arise from voxel representations.by Desai Chen.Ph. D
Signorini conditions for inviscid fluids
In this thesis, we present a new type of boundary condition for the simulation of inviscid fluids – the Signorini boundary condition. The new condition models the non-sticky contact of a fluid with other fluids or solids. Euler equations with Signorini boundary conditions are analyzed using variational inequalities. We derived the weak form of the PDEs, as well as an equivalent optimization based formulation. We proposed a finite element method to numerically solve the Signorini problems. Our method is based on a staggered grid and a level set representation of the fluid surfaces, which may be plugged into an existing fluid solver. We implemented our algorithm and tested it with some 2D fluid simulations. Our results show that the Signorini boundary cpndition successfully models some interesting contact behavior of fluids, such as the hydrophobic contact and the non-coalescence phenomenon
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