Journal of Computational and Theoretical Transport最新文献_第8页

On the Generalization of the Response Matrix Spectral Nodal Method for Neutral Particle SN Source–Detector Problems in Slab Geometry 平板几何中中性粒子SN源探测器问题响应矩阵谱节点法的推广

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2021-01-02 DOI: 10.1080/23324309.2021.1889604

J. P. Curbelo, Odair P. da Silva, R. Barros

引用次数: 2

Theoretical Aspects of Radiative Energy Transport for Nanoscale System: Thermodynamic Uncertainty 纳米系统辐射能量输运的理论方面:热力学不确定性

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-12-11 DOI: 10.1080/23324309.2020.1836496

A. Moldavanov

引用次数: 3

Eigenvalue Formulations for the PN Approximation to the Neutron Transport Equation 中子输运方程PN近似的特征值公式

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-12-11 DOI: 10.1080/23324309.2020.1856879

N. Abrate, M. Burrone, S. Dulla, P. Ravetto, P. Saracco

{"title":"Eigenvalue Formulations for the PN Approximation to the Neutron Transport Equation","authors":"N. Abrate, M. Burrone, S. Dulla, P. Ravetto, P. Saracco","doi":"10.1080/23324309.2020.1856879","DOIUrl":"https://doi.org/10.1080/23324309.2020.1856879","url":null,"abstract":"Abstract The study of the eigenvalues of the neutron transport operator yields an important insight into the physical features of the neutronic phenomena taking place in a nuclear reactor. Although the multiplication eigenvalue is the most popular because of its implication in the engineering design of multiplying structures, alternative interesting formulations are possible. In this paper the interest is focused on the multiplication, collision and time eigenvalues. The transport model is considered in the spherical harmonics approximation and the study is restricted to the one-dimensional plane geometry in the monokinetic case. The spectra of the different eigenvalues are investigated using a numerical code, validating its performance against the results available in the literature. The observation of the convergence trends allows to establish the performance of even- and odd-order approximations. It is shown that in general even-order approximations yield slightly less accurate results, nevertheless they appear to converge to the reference values. The effect of the choice of the boundary conditions according to the methodologies proposed by either Mark or Marshak is also investigated. The analysis of all the results presented allows to characterize the convergence properties of the spherical harmonics approach to neutron transport. The spectrum of the time eigenvalues retains a very rich physical meaning, as they are the actual time constants of the time-dependent solution of the transport problem. Therefore, in the last part of the paper the behavior of the pattern of the spectrum of the time eigenvalues when changing the scattering ratio and the order of the approximation is examined.","PeriodicalId":54305,"journal":{"name":"Journal of Computational and Theoretical Transport","volume":"50 1","pages":"407 - 429"},"PeriodicalIF":0.7,"publicationDate":"2020-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23324309.2020.1856879","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44718672","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: 5

On the Ronen Method in Simple 1-D Geometries for Neutron Transport Theory Solutions 中子输运理论解的简单一维几何Ronen方法

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-11-23 DOI: 10.1080/23324309.2020.1843496

D. Tomatis, R. Gross, E. Gilad

{"title":"On the Ronen Method in Simple 1-D Geometries for Neutron Transport Theory Solutions","authors":"D. Tomatis, R. Gross, E. Gilad","doi":"10.1080/23324309.2020.1843496","DOIUrl":"https://doi.org/10.1080/23324309.2020.1843496","url":null,"abstract":"Abstract In this work, we apply the Ronen method to obtain highly-accurate approximations to the solution of the neutron transport equation in simple homogeneous problems. Slab, cylindrical, and spherical geometries are studied. This method demands successive resolutions of the diffusion equation, where the local diffusion constants are modified in order to reproduce new estimates of the currents by a transport operator. The diffusion solver employs here finite differences and the transport-corrected currents are forced in the numerical scheme by means of drift terms, like in the CMFD scheme. Boundary conditions are discussed introducing proper approximations to save the particle balance in case of reflection in the slab. The solution from the Ronen iterations is compared against reference results provided by the collision probability method. More accurate estimates of the currents are provided by integral transport equations using first flight escape probabilities. Slow convergence on the scalar flux is analyzed, although the results match the reference solutions in the limit of fine meshes and far from the bare boundary.","PeriodicalId":54305,"journal":{"name":"Journal of Computational and Theoretical Transport","volume":"50 1","pages":"134 - 157"},"PeriodicalIF":0.7,"publicationDate":"2020-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23324309.2020.1843496","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46773396","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: 3

Subdiffusion of Particles with a Nonlinear Interaction and Cell-Cell Adhesion 非线性相互作用粒子的扩散与细胞粘附

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-11-11 DOI: 10.1080/23324309.2020.1840395

A. Al-Sabbagh

引用次数: 0

Extended Validity of the Energy Dependent Scattering Kernel within the Boltzmann Transport Equation Boltzmann输运方程中能量相关散射核的扩展有效性

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-11-09 DOI: 10.1080/23324309.2020.1836497

R. Dagan, A. Konobeev

{"title":"Extended Validity of the Energy Dependent Scattering Kernel within the Boltzmann Transport Equation","authors":"R. Dagan, A. Konobeev","doi":"10.1080/23324309.2020.1836497","DOIUrl":"https://doi.org/10.1080/23324309.2020.1836497","url":null,"abstract":"Abstract The scattering term within the Boltzmann equation was for decades approximated either through the Legendre polynomial for deterministic solvers or by /free gas model approach for Monte Carlo solvers. This, to some extent, inaccurate approach led to the assumption in several cases that the scattering term can be further “tuned” to simplify complex mathematical solver of the transport equation, mainly by reducing considerably the computation time, assuming no consequences on the physical results. The introduction of the resonant dependent scattering kernel to MONTE CARLO code and in particular the experimental validation within the resolved resonance range for Uranium and Thorium, in RPI (Renselear Polytechnic Institute), pointed out that the scattering term cannot be taken as a second order negligible term, but rather should be accurately regarded for any solution of the transport equation. Corollary to the considerable high impact of that “physical” scattering kernel, this study extends its importance beyond the epithermal resolved resonance range and aims to proof that the scattering kernel can and should be accurately dealt also at higher energies at least up to about several tens of keV. Moreover, in the debate between the purely quantum mechanics treatment known as the Optical Model -OM and the Doppler broadening based classical approach, the latter seems to be correct for this extended energy range. Strictly speaking, Newton’s Laws for the scattering kernel evaluation remain intact, yet in accordance to their quantum mechanics based integrated scattering cross section values as was shown for example by the well-known fundamental Breit Wigner formula.","PeriodicalId":54305,"journal":{"name":"Journal of Computational and Theoretical Transport","volume":"50 1","pages":"364 - 376"},"PeriodicalIF":0.7,"publicationDate":"2020-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23324309.2020.1836497","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47983342","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

Comparing Kinetic and MEP Model of Charge Transport in Graphene 石墨烯中电荷输运动力学模型与MEP模型的比较

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-11-09 DOI: 10.1080/23324309.2020.1822870

Liliana Luca, G. Mascali, G. Nastasi, V. Romano

引用次数: 3

Analytical Solution of a Gas Release Problem considering Permeation with Time-Dependent Boundary Conditions 考虑渗透时边界条件下气体释放问题的解析解

IF 0.7 4区工程技术

Journal of Computational and Theoretical Transport Pub Date : 2020-11-09 DOI: 10.1080/23324309.2020.1828469

M. Schulz, K. Nagatou, A. von der Weth, F. Arbeiter, V. Pasler

{"title":"Analytical Solution of a Gas Release Problem considering Permeation with Time-Dependent Boundary Conditions","authors":"M. Schulz, K. Nagatou, A. von der Weth, F. Arbeiter, V. Pasler","doi":"10.1080/23324309.2020.1828469","DOIUrl":"https://doi.org/10.1080/23324309.2020.1828469","url":null,"abstract":"Abstract In preparation for determining material properties such as Sieverts’ constant (solubility) and diffusivity (transport rate) we give a detailed discussion on a model describing some gas release experiment. Aiming to simulate the time-dependent hydrogen fluxes and concentration profiles efficiently, we provide an analytical solution for the diffusion equations on a cylindrical specimen and a cylindrical container for three boundary conditions (B.C.). These (B.C.) occur in three phases – loading phase, evacuation phase and gas release phase. In the loading phase the specimen is charged with hydrogen assuring a constant partial pressure of hydrogen. The gas will be quickly removed in the second phase, in the third phase, the hydrogen is released from the specimen to the gaseous phase. The diffusion equation in each phase is a simple homogeneous equation. Due to the complex time-dependent (B.C.), we transform the homogeneous equations to the non-homogeneous ones with a zero Dirichlet (B.C.). Compared with the time consuming numerical methods our analytical approach has an advantage that the flux of desorbed hydrogen can be explicitly given and therefore can be evaluated efficiently. Our analytical solution also assures that the (B.C.) are exactly satisfied. The interaction between specimen and container is taken into account.","PeriodicalId":54305,"journal":{"name":"Journal of Computational and Theoretical Transport","volume":"49 1","pages":"389 - 412"},"PeriodicalIF":0.7,"publicationDate":"2020-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23324309.2020.1828469","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48376214","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: 4

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