Mathematical Models and Computer Simulations最新文献

{"title":"About One Spatial Filtration Model with a Nonclassical Law of Motion in a Hydrate-Containing Environment","authors":"A. E. Bakeer, Yu. A. Poveshchenko, V. O. Podryga, P. I. Rahimly","doi":"10.1134/s2070048224700236","DOIUrl":"https://doi.org/10.1134/s2070048224700236","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>This study proposes a spatial two-component (H₂O, CH₄), three-phase (hydrate, free water, and gas) filtration model, taking into account the dissociation of gas hydrates, based on splitting by physical processes, using a nonclassical law of motion (taking its nonlinearity into account). The presented mathematical model makes it possible to calculate two-dimensional flows in areas with an irregular strata structure. With its help, it is possible to carry out both profile and areal calculations, taking into account the complex geometry of sedimentary basins. When testing it to solve problems of the theory of filtration in sedimentary basins, the method of support operators is applied and implemented. This method makes it possible to calculate filtration processes in media with discontinuous physical properties, which is achieved by using irregular meshes. As a result, it becomes possible to model the shear zones and obtain a numerical solution under conditions of different scales of the problem. At the same time, on meshes with large cells, where there are discontinuities in the material properties, a qualitative approximation of the transfer of the saturation and gradients of the thermodynamic quantities is preserved. The constructed mesh model also approximates the identities of the support operator method on different time layers. Based on the developed computing technology, a software package is created, whose tools are capable of solving two-dimensional problems of multiphase and multicomponent modeling of gas hydrate dissociation processes in the porous environment of sedimentary basins of a lithologically complex structure on meshes of an irregular structure. To test the software package, model calculations of piezoconductive processes in a three-phase medium with hydrated solid-phase inclusions in a two-dimensional case on irregular meshes are carried out. The calculations show a decrease in the depression value within the spatial regions when using nonlinear filtration laws of motion in the medium compared to the classical Darcy law, which makes it possible to correctly describe the physics of low-permeability reservoirs.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190198","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}

{"title":"Application of WENO-Schemes for Modelling Shock-Wave Processes","authors":"F. A. Belolutskiy, V. V. Shepelev, S. V. Fortova","doi":"10.1134/s2070048224700200","DOIUrl":"https://doi.org/10.1134/s2070048224700200","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>This paper analyzes weighted essentially non-oscillatory (WENO)-schemes for the solution of one-dimensional Euler equations with a Mie−Grüneisen type of equation of state. The least dissipative and oscillatory modifications of WENO-schemes in characteristic variables with a monotonicity-preserving (MP) limiter are presented. A modified scheme, MP-WENO-SM, is developed, demonstrating the smallest amplitude of oscillations in the solution of the test problems with discontinuous initial data.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190201","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}

{"title":"Coupling Model for Real-Time Simulation of a Sailing Ship’s Motion under the Influence of Irregular Waves and Wind","authors":"A. L. Zheleznyakova","doi":"10.1134/s2070048224700273","DOIUrl":"https://doi.org/10.1134/s2070048224700273","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The development of the interactive models for coupled dynamics of floating bodies in changing environments and wind-wave-body interactions is of paramount importance. This study presents a computationally cost-effective approach that implements the simplified but physically based submodels combined into a single system. A realistic geometric model of a complex-shaped sailing ship, which is rigged with adjustable sails and steered by a rudder, is selected as the object of numerical research. The irregular wind waves are simulated using in situ records of the sea surface, probability description, and inverse fast Fourier transform. The complicated geometries of a floating object and arbitrary overwater obstacles, as well as a changeable sea surface, are represented as high-resolution triangular meshes. A six-degrees-of-freedom motion model for an immersed rigid body is also integrated. A technique for the computation of wind loads on arbitrary-shaped adjustable sails, a ship’s hull, masts, and superstructures is proposed. The ship-generated waves that propagate and reflect off arbitrary obstacles are modeled using the linearized wave theory in conjunction with the two-dimensional convolution and masking operations, which are applied to the wave height field. A combination of the above approaches allows real-time conjugate modeling of the dynamics of a ship exposed to wind and irregular waves. A real sailing ship and a virtual one are compared using an experimental polar diagram in terms of the speed characteristics.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190199","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}

{"title":"Numerical Simulation of a Gas Flow in a Stage-Diffuser System in a Wide Range of Modes with Experimental Verification","authors":"M. G. Cherkasova, V. A. Chernikov, E. Yu. Semakina","doi":"10.1134/s2070048224700212","DOIUrl":"https://doi.org/10.1134/s2070048224700212","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Usually at the design stage of a gas turbine unit (GTU) the nominal operating mode is considered. This mode is defined by the axial exit of the flow from the turbine, in order to reduce losses with the exhaust velocity. Axial entry into the diffuser is optimal, due to the absence of incidence angle on the support struts. Struts are the integral part of the diffuser, where the rear bearing support of the turbine rotor is located. However, the GTU operates for a long time both in the nominal and in variable modes. Partial modes are characterized by significant incidence angles on the struts, which leads to flow separation and a notable increase in pressure losses in the diffuser. Maintaining a satisfactory flow in the diffuser in a wide range of modes is an important issue. In this paper, the stage-diffuser system is studied by experimental and numerical methods in a wide range of modes. This study shows that at the last stage when the flow angle is less than 50°, the flow in the diffuser acquires an asymmetric character with the developed vortices. This means that numerical simulation in an engineering approach cannot repeat the nature of the flow at low load modes. Nevertheless, a comparison of the total parameters of the experiment and simulation shows close agreement (a difference of about 5%) even for modes with large incidence angles on the diffuser struts.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190175","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}

{"title":"A Model of the Russian Banking System with a Breakdown of the Main Asset and Liability Categories by Maturity","authors":"N. P. Pilnik, S. A. Radionov","doi":"10.1134/s2070048224700224","DOIUrl":"https://doi.org/10.1134/s2070048224700224","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A new version of the model of the Russian banking system, which describes the dynamics of a wide range of indicators of banking activity, is presented. Compared to the previous version of the model, a breakdown of the volumes of ruble loans and deposits of businesses and households by maturity has been added. It is shown that the model makes it possible to accurately reproduce a wide range of performance indicators of the Russian banking system, outperforming the econometric analogs for most variables.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190177","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}

{"title":"Numerical Modeling of a Groundwater Flow in Fractured Porous Media Based on the DFM Approach","authors":"F. V. Grigorev","doi":"10.1134/s207004822470025x","DOIUrl":"https://doi.org/10.1134/s207004822470025x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The approaches used to model a groundwater flow in fractured porous media are reviewed and their merits and shortcomings are discussed. The discrete fracture and matrix (DFM) model implemented in the GeRa software is described, emphasizing its capacity to explicitly consider the geometry of fractures and the water exchange between fractures and the porous matrix. The use of a multipoint flux approximation on the fracture within the finite volume method based on the O‑scheme is proposed. The implemented numerical scheme is applied to solve a practical problem of estimating the water inflow into an underground research laboratory in a fractured rock massif.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190197","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}

{"title":"Heterogeneous Parallel Implementation of a Multigrid Method with Full Approximation in the Noisette Code","authors":"A. V. Gorobets, S. A. Soukov, A. R. Magomedov","doi":"10.1134/s2070048224700261","DOIUrl":"https://doi.org/10.1134/s2070048224700261","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>This article studies accelerating simulations of compressible flows on hybrid cluster systems using the full approximation scheme multigrid (FAS MG) method. The basic numerical algorithm has the following features: for spatial discretization, unstructured mixed-element meshes and schemes with the definition of mesh functions at mesh nodes are used; for temporal discretization, a fully implicit scheme is used. The aim of this study is to achieve acceleration of stationary simulations on both central and graphics processors without significant losses in parallel efficiency. We describe an approach to construct mesh levels; a technique for improving the quality of the mesh representation of the geometry of the modeled objects; and parallel implementation within the framework of complex parallelization, combining the message passing interface (MPI) for a distributed-memory parallel model, OpenMP for a shared-memory model, and OpenCL for computing on GPUs of various architectures.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190202","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}

{"title":"Numerical Modeling of Compressible Mixing Layers with a Bicompact Scheme","authors":"M. D. Bragin","doi":"10.1134/s2070048224700194","DOIUrl":"https://doi.org/10.1134/s2070048224700194","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A bicompact scheme for the Navier–Stokes equations is considered in the case of a compressible heat-conducting fluid. The scheme is constructed using splitting by physical processes and it has the fourth order of approximation in space and the second order of approximation in time. New, conservative formulas are derived for transitions between two different representations of the numerical solution in bicompact schemes for hyperbolic and parabolic equations. The parallel implementation of the bicompact scheme is tested for strong scalability. The bicompact scheme is applied to the three-dimensional direct numerical simulation of the mixing layer with convective Mach numbers of 0.4 and 0.8. In the calculated flows, the zone of turbulent mixing is resolved in detail, and the phenomena observed in experiments are adequately reproduced. Good quantitative agreement is demonstrated with the simulations carried out by other authors.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190173","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}

{"title":"Some Ways of Parallel Implementation of the Conjugate Gradient Method with an Implicit Factorized Preconditioner","authors":"O. Yu. Milyukova","doi":"10.1134/s2070048224700285","DOIUrl":"https://doi.org/10.1134/s2070048224700285","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The paper considers two ways of using MPI and MPI + OpenMP technologies for constructing and inverting the preconditioner of an incomplete triangular Cholesky decomposition without filling IC(0) for solving systems of linear algebraic equations with an arbitrary symmetric positive definite matrix. They differ in the way in which the preconditioning matrix IC(0) is computed. Methods of using MPI and MPI + OpenMP technologies are based on the use of grid node orderings consistent with the division of the calculation area. Comparative timing results for the MPI + OpenMP and MPI implementations of the proposed preconditioning IC(0) used with the conjugate gradient method for a model problems and the sparse matrix collections SuiteSparse, as well as comparing the time required to solve these problems using the two MPI and MPI + OpenMP technology methods, are presented.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190200","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}

{"title":"Numerical Modeling of Noise Generation by Different Propeller Configurations of a Multicopter","authors":"A. A. Aksenov, S. F. Timushev, D. V. Klimenko, S. Yu. Fedoseev, P. A. Moshkov","doi":"10.1134/s2070048224700248","DOIUrl":"https://doi.org/10.1134/s2070048224700248","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Lightweight multicopters (drones) are widely used for commercial and other activities. In the developed countries of Europe and the United States, legislative measures are beginning to be developed to limit the noise of multicopters; thus, the low noise level of a propeller multicopter is an important factor in competitiveness. This requires the development of computational aeroacoustics methods in combination with computer-aided design systems for drones, including propellers. The application of the method of decomposition of vortex and acoustic modes in a subsonic isentropic flow, described in this article, makes it possible to consider the factors of the inhomogeneity of the flow and rotor interference. For a feasibility study, a single-processor version of the software is used, which implements this method in the time domain for the propeller blade passing frequency (BPF). The comparative characteristics of the sound field parameters for different rotor configurations in the hovering mode above the ground are presented. The necessity of optimizing the mutual position of the propellers of the multicopter to ensure a low level of radiated sound power is shown.</p>","PeriodicalId":38050,"journal":{"name":"Mathematical Models and Computer Simulations","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190178","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}