Multiphase Systems最新文献_第6页

Application of free software FreeFem++/Gmsh and FreeCAD/CalculiX for simulation of static elasticity problems 应用自由软件FreeFem++/Gmsh和FreeCAD/CalculiX进行静态弹性问题的模拟

Multiphase Systems Pub Date : 1900-01-01 DOI: 10.21662/mfs2020.3.129

I. Nasibullayev

{"title":"Application of free software FreeFem++/Gmsh and FreeCAD/CalculiX for simulation of static elasticity problems","authors":"I. Nasibullayev","doi":"10.21662/mfs2020.3.129","DOIUrl":"https://doi.org/10.21662/mfs2020.3.129","url":null,"abstract":"The paper discusses the stages of computer numerical simulation of engineering problems and ways to improve the accuracy of simulation; provides a brief overview of free software for simulation elasticity problems by the finite element method, as well as trends in the development of free CAD and CAE software. For a successful engineering study, it is necessary to choose a convenient tool that takes into account all the features of the problem being solved. Based on the solution of a test static problem of linear elasticity, two approaches to engineering modeling were demonstrated. The first approach requires programming skills - the full modeling cycle was written in the programming language of the FreeFem++ software. Additionally, the method mesh generating in the Gmsh program with subsequent use in the FreeFem++ program is shown. In the second approach, the full cycle of modeling is carried out through the interface of the FreeCAD program with the built-in CalculiX solver, which does not require programming skills. A way to parameterize the task using the Python interpreter built into FreeCAD is also proposed. The simulation results obtained using both approaches are compared for an object to which an external action is applied, determined by the Dirichlet or Neumann boundary conditions, and two types of object fastening are analyzed: rigid embedding and limitation by a plane with zero friction. The analysis of the use of computing resources by various direct and iterative methods is carried out. Within the framework of the considered test problem of static linear elasticity, the most optimal method in FreeFem++ is the iterative method of conjugate gradients CG both in terms of computation time and in terms of the memory used. The highest speed of calculations is provided by the Cholesky iterative method with conditioning by the incomplete Cholesky expansion in the CalculiX program.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"12 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130490033","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

Proceedings of the VII Russian Conference with international participation”Multiphase Systems: Models, Experiment, Applications“ 第七届俄罗斯国际会议论文集“多相系统:模型，实验，应用”

Multiphase Systems Pub Date : 1900-01-01 DOI: 10.21662/mfs2020.1-2

引用次数: 2

On the symmetries of the generalized Korteweg-de Vries equation 关于广义Korteweg-de Vries方程的对称性

Multiphase Systems Pub Date : 1900-01-01 DOI: 10.21662/mfs2021.3.018

O. Babkov, G. Z. Mukhametova

{"title":"On the symmetries of the generalized Korteweg-de Vries equation","authors":"O. Babkov, G. Z. Mukhametova","doi":"10.21662/mfs2021.3.018","DOIUrl":"https://doi.org/10.21662/mfs2021.3.018","url":null,"abstract":"The Korteweg–de Vries equation is a third–order nonlinear partial differential equation that plays an important role in the theory of nonlinear waves, mainly of hydrodynamic origin. It was first obtained by Joseph Boussinesq in 1877, but a detailed analysis was already carried out by Diederik Korteweg and Gustav de Vries in 1895. The Korteweg–de Vries equation, its analogues and generalizations arise in mathematical models in a variety of subject areas. There are at least several thousand publications in which the Korteweg–de Vries equation is considered from one side or another, and the authors are aware of the impossibility of writing at least a simple list listing these publications. Nevertheless, it is possible to mention, for example, The paper considers some generalization of the Korteweg–de Vries equation obtained by introducing an arbitrary function with respect to which a group classification is performed. The admissible operators of the generalized Korteweg–de Vries equation, the basic algebra of admissible operators and possible cases of extension of the algebra of admissible operators for a coefficient function of a special kind are found. Tables of commutators of the obtained algebras are also calculated. At the same time, the fact of isomorphism of admissible algebras in two different cases of specification of the function-coefficient of the generalized Korteweg–de Vries equation is noted. It is shown that the maximum possible dimension of the algebra of admissible operators is equal to four and corresponds to the almost classical Korteweg–de Vries equation with a possible additional linear term. In all other cases, if the resulting algebra of admissible operators and extends, then to a three-dimensional Lie algebra.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133895857","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

Thermoviscous liquid conjugate heat exchange simulation in cylindrical channel 热粘性液体在圆柱形通道中的共轭换热模拟

Multiphase Systems Pub Date : 1900-01-01 DOI: 10.21662/mfs2022.3.013

K. V. Moiseev, I.N. Iamlikhina

{"title":"Thermoviscous liquid conjugate heat exchange simulation in cylindrical channel","authors":"K. V. Moiseev, I.N. Iamlikhina","doi":"10.21662/mfs2022.3.013","DOIUrl":"https://doi.org/10.21662/mfs2022.3.013","url":null,"abstract":"The article is concerned with the flow of a thermoviscous fluid in a cylindrical channel for various types of viscosity functions in the joint solution of the problem of conjugate heat exchange between the channel and the surrounding material. A model of a cylindrical channel with a thermoviscous liquid flowing inside at a given velocity and viscosity is considered. The methodology of the process consists in applying a system of model equations that describes the dynamics of thermoviscous fluid flow processes based on the laws of phase energy conservation, the continuity equation, the Navier-Stokes momentum conservation equation taking into account conjugate heat transfer and the heat transfer equation for a solid. Numerical implementation of model representations was carried out using the Comsol Multiphysics digital package. Velocity and temperature profiles were obtained in the cross section of the channel. The influence of the viscosity function on the flow profile is shown, as well as the quantitative characteristics of the flow and heat transfer. An analysis was made of the dependence of the nature of the velocity and temperature profiles on the viscosity of the liquid and the type of dependence of viscosity on temperature. The result of the work done is the found features and regularities that arise in the process of conjugate heat transfer of a thermoviscous liquid in a cylindrical channel when comparing the linear and exponential dependences of viscosity on temperature. The analysis of the obtained dependences of viscosity and temperature in the flow profile, the value of the maximum flow rate was carried out. It is shown that viscous friction causes a local increase in temperature near the pipe walls, followed by an increase in fluid velocity due to a decrease in viscosity. The results obtained are basic for the further development of this topic and will be used to solve new problems in the field of modeling the thermoviscous fluid flow and conjugate heat transfer.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122140503","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

Terms number determination at the series truncation for the numerical solution of the problem of acoustic scattering from a sound-permeable spheres set 可透声球群声散射问题数值解序列截断处项数的确定

Multiphase Systems Pub Date : 1900-01-01 DOI: 10.21662/mfs2020.3.128

E. Nasibullaeva

{"title":"Terms number determination at the series truncation for the numerical solution of the problem of acoustic scattering from a sound-permeable spheres set","authors":"E. Nasibullaeva","doi":"10.21662/mfs2020.3.128","DOIUrl":"https://doi.org/10.21662/mfs2020.3.128","url":null,"abstract":"Acoustic scattering from small-sized obstacles under external influence is one of the most important problems in acoustics, primarily because of the practical applications of this phenomenon. The solution of this problem is reduced to solving the Helmholtz equation for a complex potential with certain boundary conditions. When using the calculation method based on the fast multipole method, the potentials are decomposed into series according to special spherical functions, the form of which depends on the region in which this potential is calculated. As a result, the numerical implementation of the resulting matrix system raises the question of the correct choice of the number of series members when truncating them, since with a small number of series members, the calculation accuracy will be low, and with a large one will be increase not only the accuracy, but also the calculation time. An analysis of the scientific literature has shown that there are two approaches to choosing the number of terms of a series when truncating for such problems. In the first approach, truncation of the series is based on comparing two consecutive values of the sum of the sought series until the required degree of accuracy is achieved. In the second approach, all series in each expansion are truncated for a fixed number of series terms determined using heuristic formulas. In this paper, using the example of three sound-permeable spheres of different radii in the case of their strong interaction, when numerical calculations become «sensitive» to the number of terms during truncation, we compared these approaches. The analysis of the obtained data showed that to determine the value of the desired function with the necessary accuracy, it is optimal to use a combination of the considered approaches.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123834139","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

The main tasks of group analysis of differential equations of mechanics 主要任务是力学微分方程的群分析

Multiphase Systems Pub Date : 1900-01-01 DOI: 10.21662/mfs2022.1.005

S. Khabirov

引用次数: 0

Concurses for young scientists of the Mavlyutov Institute of Mechanics UFRS RAS 2021 (abstracts) 马夫柳托夫力学研究所UFRS RAS 2021青年科学家大会(摘要)

Multiphase Systems Pub Date : 1900-01-01 DOI: 10.21662/mfs2021.3.020

D. Siraeva

引用次数: 0

Analytical review of the proceedings of the conference ”Multiphase Systems: Models, Experiment, Applications“ “多相系统:模型、实验、应用”会议论文集分析综述

Multiphase Systems Pub Date : 1900-01-01 DOI: 10.21662/mfs2020.3.124

S. Urmancheev

引用次数: 1

Influence of aqueous foam syneresis on the shock wave propagation velocity 水泡沫协同作用对激波传播速度的影响

Multiphase Systems Pub Date : 1900-01-01 DOI: 10.21662/mfs2020.3.126

E. F. Gainullina

{"title":"Influence of aqueous foam syneresis on the shock wave propagation velocity","authors":"E. F. Gainullina","doi":"10.21662/mfs2020.3.126","DOIUrl":"https://doi.org/10.21662/mfs2020.3.126","url":null,"abstract":"Numerical simulation of the spherical shock pulse propagation in aqueous foam with volumetric liquid fraction of 0.0083 has been carried out in accordance with the published experimental data on the explosion of HE in aqueous foam. The assumption is used that the foam structure is destroyed by the shock wave, which leads to the transformation of the foam into a monodisperse gas-droplet mixture. The system of equations for the two-phase gas-droplet model of aqueous foam includes the laws of conservation of mass, momentum, energy for each phase and the equation for the dynamics of the volumetric liquid fraction in a single-pressure, two-velocity, two-temperature approximations in a three-dimensional formulation and takes into account the forces of the Schiller-Naumann interfacial drag, the Ranz-Marshall interphase contact heat exchange and the effect of foam syneresis on the initial distribution of its volumetric liquid fraction. Realistic equations of state in the form of Peng-Robinson and Mie-Gruneisen are used to describe the thermodynamic properties of air and water that make up a gas-droplet mixture. Numerical modeling of the processes under consideration was carried out in the open software of computational fluid dynamics OpenFOAM using the finite volume method based on the iterative two-step PIMPLE algorithm. The analysis of the effect of foam syneresis on the dynamics of shock pulse in aqueous foam is given. It was found that the uneven distribution of the liquid fraction in the foam, caused by its sedimentation under the gravity, leads to the increase in the shock pulse velocity in upper layers of the foam. In comparative analysis of numerical solutions and experimental data at sensor locations, the importance of taking into account syneresis phenomena in modeling the dynamics of shock wave in aqueous foam is shown. The reliability of calculations obtained by the proposed model is confirmed by their agreement with experimental data.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"306 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116797443","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

Two-Dimensional numerical parametric modeling of the capillary microgripper cooling system with unsteady fluid flow 非定常毛细管微夹持冷却系统的二维数值参数化建模

Multiphase Systems Pub Date : 1900-01-01 DOI: 10.21662/mfs2022.3.014

I. Nasibullayev

{"title":"Two-Dimensional numerical parametric modeling of the capillary microgripper cooling system with unsteady fluid flow","authors":"I. Nasibullayev","doi":"10.21662/mfs2022.3.014","DOIUrl":"https://doi.org/10.21662/mfs2022.3.014","url":null,"abstract":"The paper presents a parametric analysis of a 2D model of a fluid cooling system for the hot side of a Peltier element of a capillary microgripper. An unsteady flow of coolant in the cooling chamber is considered. The cooling efficiency is studied for three chamber geometries with different radiator locations: monolithic, located on the Peltier element; with one or three ribs. Mathematical models are built: fluid flow through the microgripper chamber; heating the radiator with the hot side of the Peltier element; heat transfer from the radiator to fluid and the removal of the heated fluid from the chamber. The simulation is carried out in the FreeFem++ program until the average change in the temperature of the radiator over the period of fluid oscillations reaches saturation (microgripper operating mode). Using the method of orthogonal central compositional planning, analytical dependences of response functions (maximum temperature on the radiator, amplitude of temperature change on the radiator, and time to establish the operating mode) on model factors (average coolant velocity, heat transfer coefficient, frequency and amplitude of fluid velocity oscillations) are obtained. For each considered geometry and response function, leading and insignificant factors are determined. A parametric analysis of the influence of the physical parameters of the system on the operation of the cooling system was carried out. The simulation results show that the geometry that provides a high degree of cooling and a faster exit to the operating mode (radiator with three fins) has a large amplitude of temperature fluctuations on the radiator and can be used in technical devices that are less sensitive to temperature fluctuations on the radiator. The single fin radiator geometry provides the least radiator temperature fluctuation and can be used to cool capillary microgripper.","PeriodicalId":309215,"journal":{"name":"Multiphase Systems","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132766907","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