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Boundary Elements Method for Solving Aerodynamics design Problems

Mathematical Models and computer Simulations 2019年第5期11卷 810-817页

作者： Shevelev, Yu. D. Egorov, N.A. Institute of Computer Aided Design Russian Academy of Sciences Moscow 123056 Russian Federation

Abstract: The boundary element method for numerically modeling linearized continuous media flows is considered. The method is one of the fastest among all computational aerodynamics methods. This is achieved by discarding the construction of three-dimensional computational grids, since the values to be determined during the solution of the flow problem are distributed along the surface of the layouts and, if necessary, along the surface of the vortex wake. This work is divided into the following stages: constructing a mathematical model of a complex-shaped surface and dividing it into panels, building a congruent grid on the surface, and calculating the aerodynamic characteristics of two aircraft. The results are obtained for Mach numbers corresponding to subsonic flows. © 2019, Pleiades Publishing, Ltd.

关键词： aerodynamics design panel method subsonic gas flow three-dimensional gas flows

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On kinetic model of damage development

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Procedia Structural Integrity 2020年 28卷 2032-2042页

作者： I S Nikitin N G Burago A D Nikitin B A Stratula Institute for computer aided design of RAS 2-ya Brestskaya st. 123056 Moscow Russia

A complex kinetic model of damage development under cyclic loading is proposed to describe the process of fatigue failure. Two separate models are proposed. A numerical method for calculating crack-like zones up to macro fracture is proposed. The results of numerical fatigue experiments are presented. The operability of the single criterion model and calculation algorithm is shown on experimental results. The potential operability of the double criteria model was shown; the presence of two criteria that use different types of crack nucleation may result in cases when one of the criteria leads to crack growth while the other one does not and vice versa. Under a complex stress state in the proposed double criteria model the natural implementation of any of the considered crack development mechanisms is possible. Cracks of different types may be developing simultaneously in various parts of a specimen.

关键词： Fatigue Crack Damage Crack Development

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Regularity of spots chain dynamics with intervals

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AIP Conference Proceedings 2023年第1期2953卷

作者： V. A. Gushchin I. A. Smirnova Institute for Computer Aided Design RAS 19/18 2nd Brestskaya str. Moscow Russia

The task of the spots chain dynamics with initial intervals of mixed liquid in stratified environment, and viscous flow is considered. To solve the problem, the splitting method for studying incompressible fluid flows (SMIF method) is used. The finite-different scheme of SMIF has such properties as the second order of approximation on spatial variables, minimal scheme dissipation and dispersion. The results of the formation of a streak depending on the Reynolds and Froude numbers values and the initial interval between spots are presented. Two characteristic variants were identified among the calculating variants. There are four stages of horizontal banding dynamics of spots chain with intervals.

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Model for determining of body potential 19

Model for determining of body potential

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19th International Multidisciplinary Scientific Geoconference, SGEM 2019

作者： Gushchin, Valentin Khasanov, Adam Institute for Computer Aided Design of RAS Moscow Russia Moscow Russia

ISBN: (纸本)9786197408768

The task of determining the potential of the field u( x ) of a bodyG, which is limited in space R3, is important and well known for solving both theoretical and applied problems of geodesy. The traditional approach to its solution, based on the representation of the potential in the form of series of spherical functions, has well-known advantages and disadvantages. This article discusses another model for solving the original problem in the form of an integro-differential equation u ( x) = KΔu ( x), x ∈G, where K is an integral operator with 3 a symmetric polar core, defined in a bounded domain G∈ R with boundary S of class 2 C . In the focus of the article is on justifying the suitability of the model for solving the problem and analyzing the conditions for the existence of a solution to the considered equation. Based on the known methods of mathematical physics, in particular, the method of potentials and integral Green formulas, necessary and sufficient conditions for the existence of a solution of this equation are obtained. The results are presented in the form of a theorem on the criterion for the existence of a solution for the problem. It is shown that the solution u( x) of the equation coincides with the potential of the field of the body G under consideration in the whole space. © SGEM2019. All Rights Reserved.

关键词： Integrodifferential equations

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Numerical Simulation of Detonation Initiation: The Quest of Grid Resolution 21st

Numerical Simulation of Detonation Initiation: The Quest of ...

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21st International Conference on Computational Mechanics and Modern Applied Software Systems, CMMASS 2019

作者： Lopato, Alexander I. Eremenko, Artem G. Utkin, Pavel S. Gavrilov, Dmitry A. Institute for Computer Aided Design of the RAS 19/18 Vtoraya Brestskaya ul. Moscow123056 Russia 9 Institutskiy per. Dolgoprudny Moscow Region141701 Russia

ISBN: (纸本)9789811525995

The chapter is dedicated to the numerical investigation of the grid resolution influence on the detonation initiation process in the multifocused system with the profiled end-wall. Two-dimensional system of Euler equations coupled with the single-step Arrhenius kinetic reaction mechanism was solved on completely unstructured triangular grid using the numerical scheme of second approximation order. The important technical features of interaction with SALOME software used to build an unstructured triangular computational grid, including differences in the results of the triangulation algorithms, are discussed. The content of the structure elements of the output file format CGNS of SALOME is considered. The mechanisms of detonation initiation in the multifocused system are investigated. The grid convergence problem and the influence of the resolution on flow structures are considered. © 2020, Springer Nature Singapore Pte Ltd.

关键词： Numerical models

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Modeling of Some Astrophysical Problems on Supercomputers Using Gas-Dynamic Model 21st

Modeling of Some Astrophysical Problems on Supercomputers Us...

引用

21st International Conference on Computational Mechanics and Modern Applied Software Systems, CMMASS 2019

作者： Babakov, Alexander V. Lugovsky, Alexey Y. Chechetkin, Valery M. Institute for Computer Aided Design of the RAS 19/18 Vtoraya Brestskaya ul. Moscow123056 Russia Keldysh Institute of Applied Mathematics of the RAS 4 Miusskaya pl. Moscow125047 Russia

ISBN: (纸本)9789811525995

In the current study, the vortex structures that occur in accretion disks are investigated using mathematical modeling methods. The simulation of the processes of formation of large-scale vortex structures in stellar accretion disks is carried out by two methods with different numerical schemes. The first numerical technique is based on conservative difference scheme with "upwind" approximation for fluxes. The second numerical technique is based on an explicit, conservative, monotone in the linear approximation Godunov-type Roe–Einfeldt–Osher scheme, which approximates, with order no higher than the third, the conservation laws in the form of Euler equations. Visualized pictures of the vortex structure are given by both methods for accretion disks. The qualitative similarity of the obtained results is discussed. Evolutionary calculations are carried out on the basis of parallel algorithms implemented on the supercomputing complex of the cluster architecture. © 2020, Springer Nature Singapore Pte Ltd.

关键词： Numerical methods

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On Structures of Supersonic Flow Around Plane System of Cylindrical Rods 21st

On Structures of Supersonic Flow Around Plane System of Cyli...

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21st International Conference on Computational Mechanics and Modern Applied Software Systems, CMMASS 2019

作者： Guvernyuk, Sergey V. Maksimov, Fedor A. Institute of Mechanics Lomonosov Moscow State University 1 Michurinskii prt. Moscow119192 Russia Institute of Computer Aided Design of the RAS 19/18 Vtoraya Brestskaya ul. Moscow123056 Russia

ISBN: (纸本)9789811525995

The chapter presents the results of numerical simulation of two-dimensional laminar flows near a regular system of cylinders, forming a plane lattice perpendicular to the velocity vector of the oncoming supersonic flow. A multiblock computing technology is applied using local curvilinear grids adapted to the surface of bodies and having finite areas of overlap with a global rectangular grid. The viscous boundary layers are resolved on the local grids using Navier–Stokes equations. The interaction of shock-wave structures and aerodynamic wakes behind the elements of the lattice is described within Euler equations. With a sequential increase and decrease in Mach number of the oncoming flow, several rearrangements of the flow structure near the grid are found. A multiple hysteresis was revealed, which is expressed in the fact that the flow structure and aerodynamic loads on the lattice elements depend not only on Mach number but also on the history of its change. © 2020, Springer Nature Singapore Pte Ltd.

关键词： Aerodynamics

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Cosmic voids and the kinetic analysis IV. Hubble tension and the cosmological constant

arXiv

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arXiv 2025年

作者： Gurzadyan, V.G. Fimin, N.N. Chechetkin, V.M. Center for Cosmology and Astrophysics Alikhanian National Laboratory Alikhanian Brothers str.2 0036 Armenia Yerevan State University Manukian str.1 Yerevan0025 Armenia SIA Sapienza Universita di Roma Via Salaria 851/881 Rome00191 Italy Keldysh Institute of Applied Mathematics of RAS Miusskaya Sq. 4 Moscow125047 Russia Institute of Computer Aided Design of RAS 2nd Brestskaya st. Moscow123056 Russia

The formation of cosmic structures in the late Universe was considered using the Vlasov kinetic approach. The crucial point is the use of the gravitational potential with repulsive term of the cosmological constant, which provides a solution to the Hubble tension, that is, the Hubble parameter for the late Universe has to differ from its global cosmological value. This also provides a mechanism of formation of stationary semi-periodic gravitating structures of voids and walls, so that the cosmological constant has the role of the scaling. It can therefore be compared with the observational data for given regions. The considered mechanism of the structure formation in the late cosmological epoch then succeeds the epoch described by the evolution of primordial density fluctuations. Copyright © 2025, The Authors. All rights reserved.

关键词： Cosmology

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Transmission Spectra Investigation of Nanoporous Al2O3 Matrices Filled with KDP, ADP and TGS Crystals at Visible, NIR, and SubTerahertz Ranges 11

Transmission Spectra Investigation of Nanoporous Al2O3 Matri...

引用

11th IEEE International Conference "Nanomaterials: Applications and Properties", NAP 2021

作者： Andrushchak, Nazariy Adamiv, Volodymyr Haiduchok, Volodymyr Teslyuk, Ihor Yashchyshyn, Yevhen Andrushchak, Anatoliy Computer-Aided Design Systems Lviv Polytechnic National University Lviv Ukraine Department of Optical Materials Vlokh Institute of Physical Optics Lviv Ukraine Scientific research company "Electron-Carat" Lviv Ukraine Institute of Radioelectronics and Multimedia Technology Warsaw University of Technology Warsaw Poland Department of Applied Physics and Nanomaterials Science Lviv Polytechnic National University Lviv Ukraine

ISBN: (纸本)9781665439077

In this paper, the modified technology of nanoporous aluminum oxide (Al2O3) matrices filling with the KDP, ADP, and TGS crystals is proposed. The transmission spectra of the grown structures were studied at 300-3000 nm and 50-1200 GHz spectral ranges. Because of the performed investigation, due to the significant transmission of nanoporous matrices in the terahertz range, in-depth analysis needs to be performed for their use as substrates for the implementation of nanoplasmonic devices, given the regular (periodic) structure of nanopores in these matrices. ©2021 IEEE

关键词： Aluminum oxide

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Cosmic voids and the kinetic analysis: III. Hubble tension and structure formation in the late Universe

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Astronomy and Astrophysics 2023年 677卷

作者： Gurzadyan, V.G. Fimin, N.N. Chechetkin, V.M. Center for Cosmology and Astrophysics Alikhanian National Laboratory Yerevan State University Alikhanian Brothers str. 2 0036 Manukian str.1 Yerevan0025 Armenia SIA Sapienza Universita di Roma Via Salaria 851/881 Rome Italy Keldysh Institute of Applied Mathematics of RAS Miusskaya Sq. 4 Moscow125047 Russia Institute of Computer Aided Design of RAS 2nd Brestskaya st. Moscow123056 Russia

We study structure formation in the late Universe within the Vlasov kinetic self-consistent field approach. Our work is principally focused on the use of the modified gravitational potential with a repulsive term of the cosmological constant, which is directly linked to observations that enable characterizations of the Hubble tension as the result of local and global flows. We formulate the criteria for the formation of the semi-periodic gravitating structures, along with the predictions of their quantitative scales associated with observable parameters. Our principal conclusion is that filament formation in the Local (late) Universe can proceed as a deterministic process that is distinct from the structures at larger scales that result from the essentially stochastic dynamics of density perturbations. © The Authors 2023.

关键词： Stochastic systems

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