Journal of Computational and Theoretical Transport最新文献_第9页

Partial Range Completeness of Case Eigenfunctions and Numerical Solution of Singular Integral Equations of Particle Transport Problems 粒子输运问题奇异积分方程的数值解与情形特征函数的部分范围完备性

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-11-09 DOI: 10.1080/23324309.2020.1819329

D. Sahni, R. G. Tureci, A. Z. Bozkır

引用次数: 3

Asymptotic PN Approximation in Radiative Transfer Problems 辐射传递问题的渐近PN逼近

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-11-03 DOI: 10.1080/23324309.2020.1845738

Re'em Harel, S. Burov, Shay I. Heizler

引用次数: 3

On the Effect of Angular and Spatial Discretization on Perturbation Calculations 角和空间离散化对微扰计算的影响

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-10-22 DOI: 10.1080/23324309.2020.1834407

Z. I. Böröczki, M. Szieberth, A. Rineiski, F. Gabrielli

{"title":"On the Effect of Angular and Spatial Discretization on Perturbation Calculations","authors":"Z. I. Böröczki, M. Szieberth, A. Rineiski, F. Gabrielli","doi":"10.1080/23324309.2020.1834407","DOIUrl":"https://doi.org/10.1080/23324309.2020.1834407","url":null,"abstract":"Abstract In this article, different angular flux discretization options, namely discrete ordinates representation and spherical harmonics expansion are compared from the viewpoint of the accuracy of perturbation calculations. The PARTISN discrete ordinates neutron transport solver was coupled with the SEnTRi code, developed at BME, in order to perform perturbation theory calculations in different types of geometry descriptions and angular representations. With the help of the implemented code, the effect of the angular and spatial discretization on the results of perturbation theory calculations was investigated. Exact matches were observed in Cartesian geometries with the direct perturbation method when the discrete ordinates angular representation was used, and small discrepancies were found when the spherical harmonics expansion was applied. In cylindrical geometries, slight differences were observed with both angular expansions, which originate from the nature of the adjoint transport operator in curvilinear coordinate systems. The differences can be reduced to a negligible level with increased expansion order in both cases. Small discrepancies can have a significant effect in sensitivity, uncertainty and transient calculations, which that for high accuracy calculation the discrete ordinates representation of the angular dependent flux should be used or sufficiently high expansion order with the spherical harmonics must be applied.","PeriodicalId":54305,"journal":{"name":"Journal of Computational and Theoretical Transport","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2020-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23324309.2020.1834407","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44229567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Nonlocal Effects to Neutron Diffusion Equation in a Nuclear Reactor 核反应堆中子扩散方程的非定域效应

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-09-18 DOI: 10.1080/23324309.2020.1816551

R. El-Nabulsi

引用次数: 8

A Modified Symbolic Implicit Monte Carlo Method for Time-Dependent Thermal Radiation Transport 时变热辐射输运的一种改进符号隐式蒙特卡罗方法

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-09-18 DOI: 10.1080/23324309.2020.1817087

Kai Yan

{"title":"A Modified Symbolic Implicit Monte Carlo Method for Time-Dependent Thermal Radiation Transport","authors":"Kai Yan","doi":"10.1080/23324309.2020.1817087","DOIUrl":"https://doi.org/10.1080/23324309.2020.1817087","url":null,"abstract":"Abstract Symbolic Implicit Monte Carlo (SIMC) is fully implicit in the value of matter temperature used to calculate the thermal emission. However, it means that the temporal precision of this method is limited, despite this method being more robust than Fleck and Cummings’ IMC method. In this article, we develop a new Monte Carlo method which is accurate for the thermal emission in one time step. Instead of solving a system of nonlinear equations as in SIMC, we rewrite the material energy balance equation as a system of ordinary differential equations by a waveform relaxation method. We find that the initial value problem associated with these ordinary differential equations has an analytical solution, meaning that we can convert the problem into solving a function of the material temperature at the end of a time step. We prove that the function is monotonic during a time step, so that a bisection method can be used to solve the equation. This calculation process avoids having to solve the matrix equations directly and instead they are converged by performing an outer iteration. Numerical experiments are performed to validate the accuracy and efficiency of the current approach.","PeriodicalId":54305,"journal":{"name":"Journal of Computational and Theoretical Transport","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2020-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23324309.2020.1817087","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45995171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

SP3 Limit of the 2D/1D Transport Equations with Varying Degrees of Angular Coupling 不同角度耦合度下二维/一维输运方程的SP3极限

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-09-18 DOI: 10.1080/23324309.2020.1819330

M. Jarrett, B. Kochunas, E. Larsen, T. Downar

{"title":"SP3 Limit of the 2D/1D Transport Equations with Varying Degrees of Angular Coupling","authors":"M. Jarrett, B. Kochunas, E. Larsen, T. Downar","doi":"10.1080/23324309.2020.1819330","DOIUrl":"https://doi.org/10.1080/23324309.2020.1819330","url":null,"abstract":"Abstract Two-dimensional/one-dimensional (2D/1D) methods have become popular for solving the 3D Boltzmann neutron transport equation on medium-to-large computing platforms. These methods can have a wide range of accuracy that depends largely on the fidelity of the coupling between the 2D and 1D solutions in the spatial and angular variables. In general, methods with higher-order coupling are both more accurate and more computationally expensive. In order to simplify and reduce computation, an isotropic angular coupling term is frequently used. The deficiency of this approximation compared to higher-order angular coupling has been studied experimentally, but there is insufficient theoretical analysis in the literature to supplement the experimental results. In this paper, an asymptotic analysis is applied to the 2D/1D equations with varying orders of angular coupling to facilitate comparison to the simplified PN (SPN) equations. We find that the 2D/1D method with 3 angular coupling moments preserves the 3D SP3 limit, while the 2D/1D method with isotropic coupling does not. As a result, the isotropic coupling method is theoretically less accurate in problems with strong spatial gradients in both the radial and axial dimensions. This analysis provides a theoretical basis for design and optimization of the angular coupling scheme in a 2D/1D method. The results of the theoretical analysis are confirmed by using the Takeda-Ikeda benchmark to compare the accuracy of 2D/1D methods with isotropic and anisotropic coupling implemented in MPACT to SP1 and SP3 finite difference solutions.","PeriodicalId":54305,"journal":{"name":"Journal of Computational and Theoretical Transport","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2020-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23324309.2020.1819330","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41618468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A Continuous Source Tilting Scheme for Radiative Transfer Equations in Implicit Monte Carlo 隐式蒙特卡罗辐射传递方程的连续源倾斜格式

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-09-14 DOI: 10.1080/23324309.2020.1819331

Yining Shi, Xiaole Han, Wenjun Sun, Peng Song

引用次数: 11

Discrete Transfer and Finite Volume Methods for Highly Anisotropically Scattering in Radiative Heat Analysis 辐射热分析中高度各向异性散射的离散传递和有限体积法

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-07-28 DOI: 10.1080/23324309.2020.1801749

Steven Audrey Ndjanda Heugang, Hervé Thierry Kamdem Tagne, F. B. Pelap

{"title":"Discrete Transfer and Finite Volume Methods for Highly Anisotropically Scattering in Radiative Heat Analysis","authors":"Steven Audrey Ndjanda Heugang, Hervé Thierry Kamdem Tagne, F. B. Pelap","doi":"10.1080/23324309.2020.1801749","DOIUrl":"https://doi.org/10.1080/23324309.2020.1801749","url":null,"abstract":"Abstract The present work deals with the performance assessment of the finite volume method (FVM) and discrete transfer method (DTM) in term of their abilities to accurately satisfy conservation of both scattered energy and asymmetry factor of the scattering phase function, after angular discretization and their computational time to calculate the scattering phase function, in radiative transfer problems. Studies are carried out for many representative benchmark problems dealing with one-dimensional steady state radiative heat transfer through participating gray media under diffuse incident irradiation. For problems considered, tests were performed for a wide range of optical thickness, angular resolution, and anisotropic scattering phase function approximation. The results from both DTM and FVM formulations are presented and compared with available analytical and numerical literature solutions. While the two methods were found to give practically the same results, the DTM was found to be much computationally economical than the FVM, to evaluate the scattering phase function.","PeriodicalId":54305,"journal":{"name":"Journal of Computational and Theoretical Transport","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2020-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23324309.2020.1801749","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44109818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Stretched and Filtered Multigroup Pn Transport for Improved Positivity and Accuracy 用于提高正性和准确性的拉伸和过滤多群Pn传输

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-07-28 DOI: 10.1080/23324309.2020.1800745

G. Olson

引用次数: 2

Recent Studies on Two-Dimensional Radiative Transfer Problems in Anisotropic Scattering Media 各向异性散射介质中二维辐射传输问题的最新研究

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-07-28 DOI: 10.1080/23324309.2020.1806076

K. Rui, L. Barichello, R. D. da Cunha

{"title":"Recent Studies on Two-Dimensional Radiative Transfer Problems in Anisotropic Scattering Media","authors":"K. Rui, L. Barichello, R. D. da Cunha","doi":"10.1080/23324309.2020.1806076","DOIUrl":"https://doi.org/10.1080/23324309.2020.1806076","url":null,"abstract":"Abstract In this work, an explicit formulation to solve two-dimensional radiative transfer problems in anisotropic scattering media is developed. A nodal technique along with the Analytical Discrete Ordinates (ADO) method are used to solve the discrete ordinates approximation of the radiative transfer equation, in Cartesian geometry. To make it possible, the discrete ordinates equations are transversally integrated over regions of the domain reducing the complexity of the model, yielding two one-dimensional equations for average angular intensities in x and y directions. The one-dimensional equations, with approximations for the unknown intensities on the contours of the regions, are then explicitly solved by the ADO method, with respect to the spatial variables, whose solutions are written in terms of eigenvalues and eigenfunctions. The phase function is expanded in terms of Legendre polynomials up to arbitrary order L, to model higher order anisotropy. The eigenvalue problem is derived for this general case and it preserves a relevant feature of the ADO method, which is the reduced order equal to half of the number of discrete directions. Numerical results for the average radiation density and radiative heat flux are presented, for test cases in which the degree of anisotropy can be up to twelve and the albedo assumes different values. A comparative analysis with results available in the literature allows the verification of the formulation and indicates a good performance of the proposed method in coarser meshes.","PeriodicalId":54305,"journal":{"name":"Journal of Computational and Theoretical Transport","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2020-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23324309.2020.1806076","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41737915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2