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A Semi-Analytical Description of Radiation Coupled with Thermal Wave Conductive Transfer in Inhomogeneous Solid Cylinder 非均匀固体圆柱体中辐射与热波传导耦合的半解析描述
4区 工程技术 Q3 MATHEMATICS, APPLIED Pub Date : 2023-06-07 DOI: 10.1080/23324309.2023.2257670
Guillaume Lambou Ymeli
AbstractThis study presents the analytical layered solution for thermal radiations coupled with non-Fourier conductive heat transfer, formulated from the Cattaneo-Vernotte flux model in inhomogeneous solid cylinder. This solution is built by combining the spherical harmonics for volumetric thermal radiations with the D1Q3 scheme of lattice Boltzmann method (LBM) for hyperbolic energy equation where the gradient of static particle distribution function was discretized at implicit time. The accuracy of the proposed model for dealing with radiation/conduction problems is investigated by considering a semitransparent radiative transfer in a cylinder with temperature dependent thermal conductivity and space dependent scattering albedo. The effects of different parameters, such as scattering albedo, refractive index, thermal conductivity, emissivity, optical thickness, and the conduction-radiation parameter on both radiations and temperature distributions for steady and transient states are studied. Results of the present work are benchmarked against those available in the literature with accuracy greater than 98.9% for a large interval of parameter sets and therefore, excellent agreement has been obtained. It also establishes from this study that the proposed layered approach is an efficient and accurate method for radiative analysis in inhomogeneous media while the D1Q3 scheme is suitable to accommodate thermal wave front in non-Fourier analysis.Keywords: Non-Fourier conductionradiationspherical harmonics methodLattice Boltzmann methodsolid cylinder Disclosure statementNo potential conflict of interest was reported by the authors.
摘要本文从非均匀固体圆柱体的Cattaneo-Vernotte通量模型出发,给出了热辐射耦合非傅立叶传导传热的分层解析解。将体积热辐射的球面谐波与晶格玻尔兹曼方法(LBM)的D1Q3格式相结合,建立了在隐式时间离散静态粒子分布函数梯度的双曲能量方程的解。通过考虑具有温度相关导热系数和空间相关散射反照率的圆柱体中的半透明辐射传递,研究了所提模型处理辐射/传导问题的准确性。研究了散射反照率、折射率、导热系数、发射率、光学厚度、导辐射参数等参数对稳态和瞬态辐射和温度分布的影响。本工作的结果与文献中可用的结果进行了基准测试,在参数集的大间隔内精度大于98.9%,因此,获得了非常好的一致性。本研究还表明,分层方法对于非均匀介质的辐射分析是一种有效而准确的方法,而D1Q3方案适用于非傅立叶分析中的热波前。关键词:非傅立叶传导辐射球面谐波法晶格玻尔兹曼法固体圆柱体披露声明作者未报告潜在利益冲突。
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引用次数: 1
On Multivariate Distribution of n-Dimensional Brownian Diffusion Particle in the Fluid 流体中n维布朗扩散粒子的多元分布
4区 工程技术 Q3 MATHEMATICS, APPLIED Pub Date : 2023-06-07 DOI: 10.1080/23324309.2023.2254951
Mohamed Abd Allah El-Hadidy, Alaa Awad Alzulaibani
This work presents the multivariate distribution of an n-dimensional independent Brownian particle’s position at any time t in the fluid. To know the diffusion properties of particle in a fluid, we study some statistical properties of this distribution. Besides that, we study the estimated value of the diffusion coefficient to present more information about the particle’s motion in the fluid.
这项工作提出了一个n维独立布朗粒子在任何时间t在流体中的位置的多元分布。为了了解粒子在流体中的扩散特性,我们研究了这种分布的一些统计性质。此外,我们还研究了扩散系数的估计值,以提供更多关于颗粒在流体中的运动的信息。
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引用次数: 0
Evaluation of 1D Models for Particle Transport with Wall Migration in Ducts of Rectangular Cross Section 矩形截面管道中具有壁面迁移的粒子输运一维模型的评价
IF 0.7 4区 工程技术 Q3 MATHEMATICS, APPLIED Pub Date : 2023-04-16 DOI: 10.1080/23324309.2023.2233233
R. D. Garcia, M. T. Pazianotto, Felipe L. Frigi
Abstract Approximate 1D models of particle transport in ducts that make use of an exponential displacement kernel to describe the effect of wall migration are evaluated for ducts of rectangular cross section. The studied models are based on the use of either one or two basis functions to approximate the transverse and azimuthal dependencies of the angular flux in the duct. Thermal-neutron reflection and transmission probabilities resulting from Monte Carlo simulations carried out with the MCNP and PHITS codes for iron, concrete and graphite ducts are used as reference solutions. It is concluded that the model built on two basis functions performs well (deviations typically < 10% in magnitude) for iron, the material for which absorption is most important, but less so for the scattering-dominated materials concrete and graphite. It is also concluded that changes in the energy distribution of the incident source have their strongest influence on the results for iron ducts.
摘要对矩形截面管道中颗粒传输的近似一维模型进行了评估,该模型利用指数位移核来描述壁迁移的影响。所研究的模型基于使用一个或两个基函数来近似管道中角通量的横向和方位相关性。使用MCNP和PHITS代码对铁、混凝土和石墨管道进行的蒙特卡罗模拟得出的热中子反射和透射概率作为参考解。得出的结论是,建立在两个基函数上的模型对铁(吸收最重要的材料)表现良好(偏差通常<10%),但对散射为主的材料混凝土和石墨表现较差。还得出结论,入射源能量分布的变化对铁管的结果影响最大。
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引用次数: 0
A Monte Carlo Thermal Radiative Transfer Solver with Nonlinear Elimination 具有非线性消去的蒙特卡罗热辐射传递求解器
IF 0.7 4区 工程技术 Q3 MATHEMATICS, APPLIED Pub Date : 2023-04-16 DOI: 10.1080/23324309.2023.2223410
Adam Q. Lam, T. Palmer, T. Brunner, R. Vega
Abstract In this paper, we present a new Monte Carlo method for solving the thermal radiative transfer (TRT) equations via the method of nonlinear elimination (NLEM). This method is inspired by the previous application of NLEM to thermal radiation diffusion. Our approach, called diffusion accelerated Implicit Monte Carlo (DAIMC), is a hybrid technique which combines a Monte Carlo method for solving a purely-absorbing transport equation and a diffusion solution that accounts for effective scattering, or absorption–reemission. The method aims to improve the implicitness of the traditional implicit Monte Carlo (IMC) method. We derive DAIMC generally for 3D Cartesian geometries, but in this paper, we present results and analysis in 1D slab geometry. These preliminary results indicate that DAIMC implementations may provide more accurate and robust TRT solutions than IMC in certain test problems.
摘要在本文中,我们提出了一种新的蒙特卡罗方法,通过非线性消去法(NLEM)求解热辐射传输(TRT)方程。该方法的灵感来源于之前NLEM在热辐射扩散中的应用。我们的方法称为扩散加速隐式蒙特卡罗(DAIMC),是一种混合技术,它结合了求解纯吸收输运方程的蒙特卡罗方法和考虑有效散射或吸收-再发射的扩散解。该方法旨在提高传统隐式蒙特卡罗(IMC)方法的隐式性。我们通常导出三维笛卡尔几何的DAIMC,但在本文中,我们给出了一维板几何的结果和分析。这些初步结果表明,在某些测试问题中,DAIMC实现可以提供比IMC更准确、更稳健的TRT解决方案。
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引用次数: 1
Probability of Initiation in Neutron Transport 中子输运的起始概率
IF 0.7 4区 工程技术 Q3 MATHEMATICS, APPLIED Pub Date : 2023-04-16 DOI: 10.1080/23324309.2023.2222003
P. Brown
Abstract We discuss the numerical solution of the nonlinear integro-differential equation for the probability of a divergent neutron chain in a stationary system (i.e., the probability of initiation (POI)). We follow the development described in Bell’s classic paper on the stochastic theory of neutron transport. As noted by Bell, the linearized form of this equation resembles the linear adjoint neutron transport equation. A matrix formalism for the discretized steady state (or forward) neutron equation in slab geometry is first developed, and is then used to derive the discrete adjoint equation. A main advantage of this discrete development is that the resulting discrete adjoint equation does not depend upon how the multigroup cross sections for the forward problem are obtained. That is, we derive the discrete adjoint directly from the discrete forward equations rather than discretizing directly the adjoint equation. This also guarantees that the discrete adjoint operator is consistent with the inner product used to define the adjoint operator. We discuss three approaches for the numerical solution of the POI equations, and present numerical results on several test problems. The three solution methods are a simple fixed point iteration, a second approach that is akin to a nonlinear Power iteration, and a third approach which uses a Newton-Krylov nonlinear solver. We also give sufficient conditions to guarantee the existence and uniqueness of nontrivial solutions to our discrete POI equations when the discrete system is supercritical, and that only the trivial solution exists when the discrete system is subcritical. Our approach is modeled after the analysis presented for the continuous POI equations by Mokhtar-Kharroubi and Jarmouni-Idrissi, and by Pazy and Rabinowitz.
摘要我们讨论了稳态系统中发散中子链概率的非线性积分微分方程的数值解(即引发概率(POI))。我们遵循贝尔关于中子输运随机理论的经典论文中描述的发展。正如贝尔所指出的,该方程的线性化形式类似于线性伴随中子输运方程。首先建立了板几何中离散稳态(或正向)中子方程的矩阵形式,然后用矩阵形式导出离散伴随方程。这种离散发展的一个主要优点是,所得的离散伴随方程不取决于如何获得正演问题的多群截面。也就是说,我们直接从离散正演方程中导出离散伴随,而不是直接离散伴随方程。这也保证了离散伴随算子与用于定义伴随算子的内积是一致的。我们讨论了POI方程的三种数值求解方法,并给出了几个试验问题的数值结果。三种求解方法是简单的不动点迭代,第二种方法类似于非线性幂迭代,第三种方法使用Newton-Krylov非线性求解器。我们还给出了充分的条件来保证当离散系统是超临界时,我们的离散POI方程的非平凡解的存在性和唯一性,并且当离散系统为亚临界时,只有平凡解存在。我们的方法是根据Mokhtar Kharroubi和Jarmouni Idrissi以及Pazy和Rabinowitz对连续POI方程的分析建模的。
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引用次数: 0
Half-Space Albedo Problem for Triplet Anlı-Güngör Scattering 三重态Anlı-Güngör散射的半空间反照率问题
IF 0.7 4区 工程技术 Q3 MATHEMATICS, APPLIED Pub Date : 2023-02-23 DOI: 10.1080/23324309.2023.2218843
R. G. Türeci, D. Gülderen
Abstract Introduction The Anlı-Güngör (AG) scattering function which is written in triplet form is applied to the half-space albedo problem. The aim of the study is to compare the results of albedo between the triplet AG scattering and quadratic AG scattering. Methods The analytical calculations are performed by HN method. Since the HN method is based on the usage of the Case eigenfunctions, they should be derived for the interested in this study. The tabulated results are calculated for varying the secondary neutron number and the scattering parameter. Albedo values for the triplet anisotropic scattering are convergent. A special code is used to get the numerical values in Mathematica with high precision This code holds all numerical values and the results of all algebraic process as a rational number. Thus, the round-off errors in machine language are minimized. A second and completely different numerical process is performed with the Polynomial Regression (PR) and the Artificial Neural Network (ANN). The application of the PR and ANN algorithms are studied with the calculated albedo results in this study. This application is only data mining without performing any analytical calculation. Discussion The expectation is to get bigger albedo values than the quadratic AG scattering. But the results are surprising that the triplet and the quadratic albedo results are close to each other. The result of ANN is more successful than PR results. Moreover, the intermediate values that are not in the data set can also be successfully calculated.
摘要简介将三元态形式的Anlı-Güngör (AG)散射函数应用于半空间反照率问题。研究的目的是比较三重态银散射和二次态银散射的反照率结果。方法采用HN法进行分析计算。由于HN方法是基于Case特征函数的使用,因此应该为对本研究感兴趣的人推导出它们。对二次中子数和散射参数的变化进行了计算。三态各向异性散射的反照率值是收敛的。使用特殊代码在Mathematica中获得高精度的数值,该代码将所有的数值和所有代数过程的结果保存为有理数。因此,机器语言的舍入误差被最小化。第二种完全不同的数值过程是用多项式回归(PR)和人工神经网络(ANN)进行的。结合反照率计算结果,研究了PR和ANN算法的应用。这个应用程序只是数据挖掘,不执行任何分析计算。期望得到比二次AG散射更大的反照率值。但令人惊讶的是,三重态反照率和二次反照率的结果非常接近。人工神经网络的结果比PR的结果更成功。此外,不在数据集中的中间值也可以成功计算。
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引用次数: 0
Study of Forward and Backward Scattering in Two-Region Milne Problem for Non-absorbing Medium Using a Synthetic Kernel 用合成核研究非吸收介质两区Milne问题中的前向和后向散射
IF 0.7 4区 工程技术 Q3 MATHEMATICS, APPLIED Pub Date : 2023-02-23 DOI: 10.1080/23324309.2023.2219659
Dalia A. Garbiea, A. El-Depsy, M. M. Selim, O. A. Mohamedien
Abstract In this work, the effect of an extremely anisotropic scattering function on the two-region Milne problem is studied. This scattering function divides the neutrons resulting from the collisions into three parts; part ( which moves backward, part (m) which moves forward, and part (n) which emerge isotropically from the collisions, where  + m + n = 1. The integral version of the transport equation is solved using trial functions based on Case’s eigenmodes and exponential integral function. Hence, the solution to the Milne problem is formulated in terms of characteristic quantities such as the extrapolation length and the fractional scalar flux discontinuity. Numerical results for the analytically evaluated quantities are presented. Some of our numerical results are compared with the available published results.
摘要本文研究了极各向异性散射函数对两区Milne问题的影响。这个散射函数把碰撞产生的中子分成三部分;部分(向后移动),部分(m)向前移动,部分(n)从碰撞中各向同性出现,其中+ m + n = 1。利用基于Case特征模态和指数积分函数的试函数求解输运方程的积分版本。因此,米尔恩问题的解是用外推长度和分数标量通量不连续等特征量来表示的。给出了解析求值量的数值结果。我们的一些数值结果与现有的已发表的结果进行了比较。
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引用次数: 0
High-Order Mixed Finite Element Variable Eddington Factor Methods 高阶混合有限元变Eddington因子法
IF 0.7 4区 工程技术 Q3 MATHEMATICS, APPLIED Pub Date : 2023-01-11 DOI: 10.1080/23324309.2023.2200308
Samuel S. Olivier, T. Haut
Abstract We apply high-order mixed finite element discretization techniques and their associated preconditioned iterative solvers to the Variable Eddington Factor (VEF) equations in two spatial dimensions. The mixed finite element VEF discretizations are coupled to a high-order Discontinuous Galerkin (DG) discretization of the discrete ordinates transport equation to form effective linear transport algorithms that are compatible with high-order (curved) meshes. This combination of VEF and transport discretizations is motivated by the use of high-order mixed finite element methods in hydrodynamics calculations at the Lawrence Livermore National Laboratory (LLNL). Due to the mathematical structure of the VEF equations, the standard Raviart Thomas (RT) mixed finite elements cannot be used to approximate the vector variable in the VEF equations. Instead, we investigate three alternatives based on the use of continuous finite elements for each vector component, a non-conforming RT approach where DG-like techniques are used, and a hybridized RT method. We present numerical results that demonstrate high-order accuracy, compatibility with curved meshes, and robust and efficient convergence in iteratively solving the coupled transport-VEF system and in the preconditioned linear solvers used to invert the discretized VEF equations.
摘要将高阶混合有限元离散化技术及其相关的预条件迭代求解方法应用于两个空间维度的可变Eddington因子(VEF)方程。将混合有限元VEF离散化与离散坐标输运方程的高阶间断伽辽金(DG)离散化相耦合,形成与高阶(曲线)网格兼容的有效线性输运算法。劳伦斯利弗莫尔国家实验室(LLNL)在流体力学计算中使用了高阶混合有限元方法,从而激发了VEF和输运离散化的结合。由于VEF方程的数学结构,标准的Raviart - Thomas (RT)混合有限元不能近似求解VEF方程中的矢量变量。相反,我们研究了基于对每个矢量组件使用连续有限元的三种替代方案,一种使用类似dg技术的非一致性RT方法,以及一种杂交RT方法。我们给出的数值结果表明,在迭代求解耦合输运-VEF系统和用于反演离散VEF方程的预条件线性求解器中,具有高阶精度、与曲面网格兼容、鲁棒性和高效收敛性。
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引用次数: 1
On the Semi-Analytical Solution of Displacement Thickness in a Laminar Streamwise Corner Flow Assisted by Computational Fluid Dynamics Simulation 基于计算流体动力学模拟的层流角流位移厚度半解析解
IF 0.7 4区 工程技术 Q3 MATHEMATICS, APPLIED Pub Date : 2023-01-02 DOI: 10.1080/23324309.2023.2171063
E. Bumrungthaichaichan, Prajaree Unaprom, Pakapong Sathianchok, S. Wattananusorn
Abstract In this paper, the new semi-analytical correlation for displacement thickness of laminar fluid flow along an arbitrary-angle corner formed by the intersection of two plates has been proposed because of the discrepancy in displacement thickness for strong interference corner between the present computational fluid dynamics simulation and previous analytical correlation.
摘要针对目前计算流体力学模拟与以往解析式关联在强干涉角位移厚度上存在差异的问题,提出了层流流体沿两板交点任意角位移厚度的半解析式关联。
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引用次数: 0
On a Response Matrix Solver for Slab-Geometry Neutral Particle Transport Problems in the Discrete Ordinates and Energy Multigroup Formulations Considering Non-Uniform Interior Sources 离散坐标系中板几何中性粒子输运问题的响应矩阵求解器和考虑非均匀内源的能量多组公式
IF 0.7 4区 工程技术 Q3 MATHEMATICS, APPLIED Pub Date : 2023-01-02 DOI: 10.1080/23324309.2023.2194294
L.R.C. Moraes, R. Barros, R. Vasques
Abstract We present in this work an extension of the Response Matrix (RM) method for the numerical solution of slab-geometry neutral particle transport equation in the discrete ordinates (S ) and energy multigroup formulations considering non-uniform sources. By using the term non-uniform we mean that the particle source is not spatially uniform inside the regions that compose the domain. The extended RM method, differently from the conventional RM method, is based on the solution of “source-independent” auxiliary problems (Green’s functions). The solution of these auxiliary problems is used in conjunction with the given non-uniform source to generate the sweeping matrices for the extended RM method. Numerical results with respect to both uniform and non-uniform source problems are given to illustrate the efficiency of the offered extended RM method.
摘要在这项工作中,我们提出了响应矩阵(RM)方法的扩展,用于离散坐标(S)中的平板几何中性粒子输运方程的数值解和考虑非均匀源的能量多群公式。使用术语非均匀,我们的意思是粒子源在组成域的区域内的空间不均匀。与传统的RM方法不同,扩展的RM方法基于“源无关”辅助问题(格林函数)的求解。这些辅助问题的解与给定的非均匀源一起用于生成扩展RM方法的扫描矩阵。给出了均匀和非均匀源问题的数值结果,以说明所提供的扩展RM方法的有效性。
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引用次数: 0
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Journal of Computational and Theoretical Transport
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