Mathematical Models and Computer Simulations最新文献_第6页

Parallel Numerical Implementation of Mathematical Wave Hydrodynamics Models Taking into Account the Features of the Vertical Turbulent Exchange Using Remote Sensing Data 利用遥感数据并行数值实现考虑到垂直湍流交换特征的数学波浪流体力学模型

Mathematical Models and Computer Simulations Pub Date : 2024-04-01 DOI: 10.1134/s2070048224020170

A. Sukhinov, E. Protsenko, S. Protsenko, N. D. Panasenko

引用次数: 0

On the Accuracy of Finite-Difference Schemes in Calculations of Centered Rarefaction Waves 论有限差分方案在计算居中稀释波中的准确性

Mathematical Models and Computer Simulations Pub Date : 2023-12-26 DOI: 10.1134/s2070048223070104

O. A. Kovyrkina, V. V. Ostapenko

引用次数: 0

Generalized Model Representation of the Thermal Shock Theory 热冲击理论的广义模型表示法

Mathematical Models and Computer Simulations Pub Date : 2023-12-26 DOI: 10.1134/s2070048223070062

E. M. Kartashov

{"title":"Generalized Model Representation of the Thermal Shock Theory","authors":"E. M. Kartashov","doi":"10.1134/s2070048223070062","DOIUrl":"https://doi.org/10.1134/s2070048223070062","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>This article considers the open problem of the thermal shock theory in terms of a generalized model of dynamic thermoelasticity under conditions of a locally nonequilibrium heat transfer process. The model is used for a massive body in the cases of three coordinate systems: Cartesian coordinates for a body bounded by a flat surface; spherical coordinates for a body with an internal spherical cavity; and cylindrical coordinates for a body with an internal cylindrical cavity. Three types of intensive heating and cooling are considered: temperature, thermal, and heating by the medium. The task is set to obtain an analytical solution, to carry out numerical experiments, and to give their physical analysis. As a result, generalized model representations of a thermal shock in terms of dynamic thermoelasticity are developed for locally nonequilibrium heat transfer processes simultaneously in three coordinate systems: Cartesian, spherical, and cylindrical. The presence of a curvature of the boundary surface of the thermal shock area substantiates the initial statement of the dynamic problem in displacements using the proposed corresponding compatibility equation. The latter made it possible to propose a generalized dynamic model of the thermal reaction of massive bodies with internal cavities simultaneously in Cartesian, spherical, and cylindrical coordinate systems under conditions of intense thermal heating and cooling, thermal heating and cooling, and heating and cooling by the medium. The model is considered in displacements on the basis of a local nonequilibrium heat transfer. An analytical solution for stresses is obtained and a numerical experiment is carried out; the wave nature of the propagation of a thermoelastic wave is described. A comparison is made with the classical solution without taking into account the local non-equilibrium. Based on the operational solution of the problem, design engineering relations that are important in practical terms for the upper estimate of the maximum thermal stresses are proposed.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139055192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Direct Numerical Simulation Method of Turbulence Taking the History of the Process into Account 考虑过程历史的湍流直接数值模拟法

Mathematical Models and Computer Simulations Pub Date : 2023-12-26 DOI: 10.1134/s2070048223070165

Yu. V. Yanilkin, A. R. Guzhova, L. I. Degtyarenko, V. Yu. Kolobyanin, V. A. Shmelev

引用次数: 0

Optimally Controlled Turbulent Boundary Layers in Supersonic Gas Flows 超音速气体流动中的优化控制湍流边界层

Mathematical Models and Computer Simulations Pub Date : 2023-12-26 DOI: 10.1134/s2070048223070049

K. G. Garaev, I. R. Mukhametzyanov

{"title":"Optimally Controlled Turbulent Boundary Layers in Supersonic Gas Flows","authors":"K. G. Garaev, I. R. Mukhametzyanov","doi":"10.1134/s2070048223070049","DOIUrl":"https://doi.org/10.1134/s2070048223070049","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A variational problem for a conditional extremum of the Mayer type on the construction of the distribution law of the normal component of the velocity of injection of a cooled gas into a turbulent boundary layer under a supersonic flow regime that provides the minimum value of the convective heat flux transmitted from the hot gas to the streamlined surface is considered. The isoperimetric condition is the power of the injection control system, calculated taking into account Darcy’s filtration law. To solve the optimal problem, we use the first integral for the conjugate system with respect to Lagrange multipliers, obtained earlier by the authors using the classical theorem of E. Noether on invariant variational problems and the Lie-Ovsyannikov infinitesimal apparatus. A.A. Dorodnitsyn’s method of generalized integral relations, which has proven itself well in calculating the characteristics of boundary layers under various flow regimes, is used for the calculations. A computational experiment conducted for the case of a flow around a sphere shows the effectiveness of the optimal control law found in comparison with a uniform injection: the gain in the value of the minimized functional is 16.8%. The novelty of the study lies in the development of a method for solving the variational problem using the first integral for the conjugate system, as well as the Dorodnitsyn’s method of generalized integral relations. The scientific significance of the study lies in the development of the theory of an optimally controlled boundary layer under a turbulent flow regime in supersonic gas flows. The results obtained may be of interest in the design of systems for the active thermal protection of surfaces in high-velocity gas flows.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139055757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Modeling the Nearest Neighbor Graphs to Estimate the Probability of the Independence of Data 建立近邻图模型以估算数据独立性的概率

Mathematical Models and Computer Simulations Pub Date : 2023-12-26 DOI: 10.1134/s2070048223070086

A. A. Kislitsyn

{"title":"Modeling the Nearest Neighbor Graphs to Estimate the Probability of the Independence of Data","authors":"A. A. Kislitsyn","doi":"10.1134/s2070048223070086","DOIUrl":"https://doi.org/10.1134/s2070048223070086","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The proposed method is based on calculations of the statistics of the nearest neighbor graph (NNG) structures, which are presented as a benchmark of the probabilities of the distribution of graphs by the number of disconnected fragments. The deviation of the actually observed occurrence of connectivity from the calculated one will allow us to determine the probability that this sample can be considered a set of statistically independent variables. The statements about the independence of the NNG statistics from the distribution of distances and from the triangle inequality are proved, which allows the numerical modeling of such structures. Estimates of the accuracy of the calculated statistics for graphs and their comparison with estimates obtained by modeling random coordinates of points in <i>d</i>-dimensional space are carried out. It is shown that the model of the NNGs without taking into account the dimension of the space leads to fairly accurate estimates of the statistics of graph structures in spaces of dimensionality higher than five. For spaces of smaller dimensionality, the benchmark can be obtained by directly calculating the distances between points with random coordinates in a unit cube. The proposed method is applied to the problem of analyzing the level of unsteadiness of the earthquake catalog in the Kuril–Kamchatka region. The lengths of samples of time intervals between neighboring events are analyzed. It is shown that the analyzed system as a whole is interconnected with a probability of 0.91, and this dependence is fundamentally different from the lag correlation between the sample elements.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139055188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Application of the Local Discontinuous Galerkin Method to the Solution of the Quasi-Gas Dynamic System of Equations 应用局部非连续伽勒金方法求解准气体动态方程组

Mathematical Models and Computer Simulations Pub Date : 2023-12-26 DOI: 10.1134/s207004822307013x

E. V. Shilnikov, I. R. Khaytaliev

引用次数: 0

Modeling the Elastic-Diffusion Vibrations of a Hinged Timoshenko Plate under the Action of a Distributed Surface Load 铰链式季莫申科板在分布式表面载荷作用下的弹性-扩散振动建模

Mathematical Models and Computer Simulations Pub Date : 2023-12-26 DOI: 10.1134/s2070048223070050

N. V. Grigorevskiy, A. V. Zemskov, A. V. Malashkin

引用次数: 0

Numerical Simulation of Dynamic Processes in the Medium of Fine-Grained Solid Particles 细粒固体颗粒介质中动态过程的数值模拟

Mathematical Models and Computer Simulations Pub Date : 2023-12-26 DOI: 10.1134/s2070048223070128

M. Y. Nemtsev

{"title":"Numerical Simulation of Dynamic Processes in the Medium of Fine-Grained Solid Particles","authors":"M. Y. Nemtsev","doi":"10.1134/s2070048223070128","DOIUrl":"https://doi.org/10.1134/s2070048223070128","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A mathematical model and numerical method for solving problems of the flow of two-phase mixtures of gas and fine solid particles are considered. The particles are assumed to be absolutely rigid, incompressible, and nondeformable. As the initial model, the continuum model of R.I. Nigmatulin is considered. The model has two drawbacks: it is not strictly hyperbolic (i.e., it degenerates into an elliptical one under certain flow regimes) and has a nonconservative form, which makes it difficult to solve numerically. This paper proposes a method for regularizing Nigmatulin’s model at a discrete level, which makes it possible to eliminate these shortcomings and develop a numerical model that is well-conditioned for evolutionary problems of the flow of gas-dispersed mixtures with nondeformable solid particles. The regularization method is based on splitting the original system into two subsystems, each of which is strictly hyperbolic and has a conservative form. Difference schemes of the Godunov type are developed for the numerical solution of these subsystems. Testing of the proposed model and implemented methods includes checking the preservation of a homogeneous solution and the formation of shock waves and rarefaction waves in a gas, as well as compaction and decompaction waves in the particle phase. The results of the numerical simulation of the interaction of a shock wave in a gas with a near-wall layer of particles are also presented.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139055190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

BlackOilFoam: Modelling Multiphase Flow from Laboratory Cells to Unconventional Reservoirs 黑油泡沫：从实验室细胞到非常规储层的多相流建模

Mathematical Models and Computer Simulations Pub Date : 2023-12-01 DOI: 10.1134/s2070048223070141

Soledad Fioroni, A. Larreteguy, G. Savioli

引用次数: 0