Ray Effect and False Scattering in the Discrete Ordinates Method

Chai, John C.; Lee, HaeOk S.; Patankar, S. V.

doi:10.1080/10407799308955899

Cited by 268 publications

(122 citation statements)

References 20 publications

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“…The external radiation heat flux distribution is modelled using a variant of the discrete transfer method, [35], modified using staggered ray meshes, [36,37] to minimise the ray effect, [38]. Spectral emission from the fire is modelled using a statistical narrow band model, RADCAL, [39].…”

Section: Thermal Radiation Modellingmentioning

confidence: 99%

Modeling Lifted Methane Jet Fires Using the Boundary-Layer Equations

Cumber

Spearpoint

2006

Numerical Heat Transfer, Part B: Fundamentals

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The focus of this paper is turbulent lifted jet fires. The main objective is to present a lifted jet fire methodology using the boundary layer equations as a basis. The advantages of this are finite volume mesh independent predictions of the mean flow fields can be calculated on readily available computer resources which leads to rigorous model calibration. A number of lift-off models are evaluated. The model of choice is one based on the laminar flamelet quenching concept combined with a model for the large-scale strain rate.

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Section: Thermal Radiation Modellingmentioning

confidence: 99%

Modeling Lifted Methane Jet Fires Using the Boundary-Layer Equations

Cumber

Spearpoint

2006

Numerical Heat Transfer, Part B: Fundamentals

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“…Low order S N solutions suffer from the errors known as 'ray effects' and the solution also depends on the spatial interpolation scheme used. The effect of these phenomena on accuracy and predictive capabilities of the S N method has been studied by Chai et al (1993), Coelho et al (1995a) and Selçuk and Kayakol (1996). Variable and exponential differencing schemes have been developed to avoid overshoots, undershoots and physically unrealistic results arising from spatial differencing practices.…”

Section: Methods For Complex Geometries and Recent Advancesmentioning

confidence: 99%

Calculation of Radiative Heat Transfer in Combustion Systems

Malalasekera¹,

Versteeg²,

Henson³

et al. 2002

Clean Air

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Most practical combustion systems involve complex geometry configurations and CFD techniques used for the calculation of flow and combustion in such geometries use body-fitted non-orthogonal mesh systems. This paper reviews some of the currently available radiative heat transfer calculation techniques suitable for such CFD applications. The Monte Carlo method, the discrete transfer method, the YIX method, the discrete ordinates method and the finite volume method are discussed and some notable applications related to combustion problems are reviewed. Comparative results using all the methods outlined are presented for bench mark problems and their applicability to complex geometry situations are discussed. Radiative heat flux predictions for an S.I. engine simulation are presented to demonstrate the capability of the discrete transfer method in a pent-roof complex geometry combustion chamber. The paper also describes a ray based technique for the handling of turbulence-radiation interactions in combustion and its application is demonstrated in the prediction of a methane diffusion flame.

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“…However, specular reflection and refraction may exhibit ray effects when discretized rays hit smooth specular surfaces. This effect has been discovered by the radiative heat transfer community [4] and found to be caused by the discretization of scattering directions when accurate directions are needed for specularity.…”

Section: Specular Photon Tracingmentioning

confidence: 99%

Lattice-Based Volumetric Global Illumination

Qiu

Fan

et al. 2007

IEEE Trans. Visual. Comput. Graphics

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Abstract-We describe a novel volumetric global illumination framework based on the Face-Centered Cubic (FCC) lattice. An FCC lattice has important advantages over a Cartesian lattice. It has higher packing density in the frequency domain, which translates to better sampling efficiency. Furthermore, it has the maximal possible kissing number (equivalent to the number of nearest neighbors of each site), which provides optimal 3D angular discretization among all lattices. We employ a new two-pass (illumination and rendering) global illumination scheme on an FCC lattice. This scheme exploits the angular discretization to greatly simplify the computation in multiple scattering and to minimize illumination information storage. The GPU has been utilized to further accelerate the rendering stage. We demonstrate our new framework with participating media and volume rendering with multiple scattering, where both are significantly faster than traditional techniques with comparable quality.

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Ray Effect and False Scattering in the Discrete Ordinates Method

Cited by 268 publications

References 20 publications

Modeling Lifted Methane Jet Fires Using the Boundary-Layer Equations

Modeling Lifted Methane Jet Fires Using the Boundary-Layer Equations

Calculation of Radiative Heat Transfer in Combustion Systems

Lattice-Based Volumetric Global Illumination

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