{"title":"Analysis of Fundamentals of Calculation and Measuring Techniques in Fluid Dynamics","authors":"Yu. D. Chashechkin","doi":"10.1134/s1063784224700518","DOIUrl":null,"url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The logics of contemporary scientific researches includes the requirement of formulation for distinctive determining the branch of science, the physical medium, and methods for solving problems. Flows are studied in two scientific disciplines, vis., engineering mathematics and technical physics. A flowing medium is characterized by equations of state for the Gibbs potential, density, and velocity of sound, as well as kinetic and other physical coefficients. Fluid flows are treated as transport of momentum, energy, and mass, which causes self-consistent changes in other physical quantities. Flows are described by the unified system of fundamental equations for all media (differential form of conservation laws). Calculations are performed in the algebra of complex numbers, where frequency is assumed to be real-valued, while wavenumber is complex-valued. Natural stratifications of the atmosphere and ocean are characterized by the buoyancy parameters. The classification of flow components is based on complete solutions to linearized and weakly nonlinear forms of fundamental equations, which are obtained by the methods of the singular perturbation theory. Regular components of solutions describe flows and waves on the surface of in the bulk of a fluid, while singular solutions describe the fine structure of the medium. In experiments performed on the stands of the Unique Hydrophysical Complex of the Ishlinsky Institute for Problems in Mechanics, Russian Academy of Sciences, upstream perturbations, internal wave fields, wakes with submerged and suspended vortices structured by interfaces and fibers during the motion of a plate, cylinder, and sphere in stratified and homogeneous fluids are singled out. Numerical calculations of a flow past a plate in a wide range of Reynolds numbers, including creeping flows with Re ~ 1 and nonstationary vortex regimes with Re ~ 100 000, are in qualitative agreement with the observations of schlieren patterns of flows in a stratified aqueous medium in the laboratory basin and in wind tunnels. The conditions for the extension of results to flows in natural conditions and problems in metrology in flight regimes are considered shortly.</p>","PeriodicalId":783,"journal":{"name":"Technical Physics","volume":null,"pages":null},"PeriodicalIF":1.1000,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Technical Physics","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1134/s1063784224700518","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"PHYSICS, APPLIED","Score":null,"Total":0}
引用次数: 0
Abstract
The logics of contemporary scientific researches includes the requirement of formulation for distinctive determining the branch of science, the physical medium, and methods for solving problems. Flows are studied in two scientific disciplines, vis., engineering mathematics and technical physics. A flowing medium is characterized by equations of state for the Gibbs potential, density, and velocity of sound, as well as kinetic and other physical coefficients. Fluid flows are treated as transport of momentum, energy, and mass, which causes self-consistent changes in other physical quantities. Flows are described by the unified system of fundamental equations for all media (differential form of conservation laws). Calculations are performed in the algebra of complex numbers, where frequency is assumed to be real-valued, while wavenumber is complex-valued. Natural stratifications of the atmosphere and ocean are characterized by the buoyancy parameters. The classification of flow components is based on complete solutions to linearized and weakly nonlinear forms of fundamental equations, which are obtained by the methods of the singular perturbation theory. Regular components of solutions describe flows and waves on the surface of in the bulk of a fluid, while singular solutions describe the fine structure of the medium. In experiments performed on the stands of the Unique Hydrophysical Complex of the Ishlinsky Institute for Problems in Mechanics, Russian Academy of Sciences, upstream perturbations, internal wave fields, wakes with submerged and suspended vortices structured by interfaces and fibers during the motion of a plate, cylinder, and sphere in stratified and homogeneous fluids are singled out. Numerical calculations of a flow past a plate in a wide range of Reynolds numbers, including creeping flows with Re ~ 1 and nonstationary vortex regimes with Re ~ 100 000, are in qualitative agreement with the observations of schlieren patterns of flows in a stratified aqueous medium in the laboratory basin and in wind tunnels. The conditions for the extension of results to flows in natural conditions and problems in metrology in flight regimes are considered shortly.
摘要当代科学研究的逻辑包括要求制定明确的科学分支、物理介质和解决问题的方法。工程数学和技术物理这两个科学学科研究流动问题。流动介质的特征是吉布斯势、密度和声速的状态方程，以及动力学和其他物理系数。流体流动被视为动量、能量和质量的传输，从而引起其他物理量的自洽变化。流体流动由适用于所有介质的统一基本方程系统（守恒定律的微分形式）来描述。计算在复数代数中进行，其中假设频率为实值，而波长为复值。大气和海洋的自然分层以浮力参数为特征。流动成分的分类基于基本方程线性化和弱非线性形式的完整解，这些解是通过奇异扰动理论方法获得的。解的规则成分描述了流体表面和体积中的流动和波浪，而奇异解则描述了介质的细微结构。在俄罗斯科学院伊什林斯基力学问题研究所独特的水文物理综合实验台上进行的实验中，研究了板块、圆柱体和球体在分层和均质流体中运动时的上游扰动、内波场、带有界面和纤维结构的沉没和悬浮涡旋的漩涡。在很大的雷诺数范围内，包括 Re ~ 1 的蠕动流和 Re ~ 100 000 的非稳态涡旋状态，对流过板的流动进行了数值计算，计算结果与在实验室盆地和风洞中观察到的分层水介质中流动的离层模式基本一致。稍后将讨论将结果推广到自然条件下流动的条件以及飞行状态下的计量问题。
期刊介绍：
Technical Physics is a journal that contains practical information on all aspects of applied physics, especially instrumentation and measurement techniques. Particular emphasis is put on plasma physics and related fields such as studies of charged particles in electromagnetic fields, synchrotron radiation, electron and ion beams, gas lasers and discharges. Other journal topics are the properties of condensed matter, including semiconductors, superconductors, gases, liquids, and different materials.
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