Fluid Dynamics最新文献

{"title":"On the Influence of Turbulence on the Coagulation of Droplets in the Process of Bulk Condensation in Vapor–Gas Flow","authors":"A. A. Sidorov,&nbsp;A. K. Yastrebov","doi":"10.1134/S0015462825603584","DOIUrl":"10.1134/S0015462825603584","url":null,"abstract":"<p>Bulk condensation is one of the frequently encountered and exploited processes in the technologies of gas purification from impurities. The phase transition process can be conditionally divided into stages of the droplet formation and growth due to two simultaneously acting mechanisms, namely, continuing vapor condensation on the surface of formed droplets and droplet coagulation due to their collisions. Early computational estimates in regard to coagulation showed a good qualitative agreement between the calculated and experimental data, but there was a significant quantitative difference. Within the framework of the present study, a hypothesis about a possible reason of these differences is put forward: turbulent disturbances are not considered in the one-dimensional formulation. The main aim is to test the hypothesis on the need to take turbulence into account within the framework of the calculation model for expanding flow in which bulk condensation takes place. The proposed modification of the approach makes it possible to take into account the effect of turbulent disturbances on coagulation of condensation aerosol particles. This can be essential, for example, in vapor–liquid turboexpanders. The study considers the bulk condensation of heavy water vapor mixed with nitrogen, acting as a non-condensable carrier gas, in the flow part of a Laval slot nozzle with regard to coagulation and turbulence. The hypothesis on the effect of turbulence in the system of gas dynamics equations on the process of droplet (particle) coagulation of a condensing impurity in the flow is confirmed. It is found that taking turbulence into account significantly improves the numerical convergence of calculations and experiment; however, it does not provide exact agreement, which, in turn, may be caused by the adopted assumption of the Brownian coagulation approximation, as well as the use of the <i>k</i>–ω turbulence model. It is shown that taking turbulence into account affects the magnitude of the coagulation kernel, the maximum difference for calculations with and without turbulence being approximately 10%. Taking into account turbulence during coagulation, droplets (particles) grow to larger sizes, which in the long term makes it possible to control this process.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 8","pages":""},"PeriodicalIF":0.6,"publicationDate":"2026-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147339342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of the Specifics of Steady Liquid Flow through a Submillimeter Hole under Vacuum Conditions","authors":"A. S. Yaskin,&nbsp;A. E. Zarvin,&nbsp;O. A. Kabov,&nbsp;D. Yu. Kochkin,&nbsp;A. S. Mungalov,&nbsp;V. V. Kalyada,&nbsp;K. A. Dubrovin,&nbsp;V. V. Cheverda,&nbsp;N. E. Sibiryakov,&nbsp;V. E. Khudozhitkov","doi":"10.1134/S0015462825603778","DOIUrl":"10.1134/S0015462825603778","url":null,"abstract":"<p>This paper examines the steady-state outflow of ethanol microjets in a metastable superheated state into a highly rarefied medium, accompanied by physical phenomena absent in dense gaseous environments. The formation of microjets in the form of curved, temporally and spatially unstable flows that disintegrate into droplets is reported. Flow bifurcation and explosive boiling of ethanol jets at the outlet, resulting in vapor–droplet streams, have been observed. Droplet formation on the surface of the flow source and the motion of these droplets along the surface in a direction opposite to the jet flow have also been detected, regardless of the orientation of the source in space. A mechanism explaining this reverse droplet motion is proposed.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 7","pages":""},"PeriodicalIF":0.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147336963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Modeling of Gas-Dispersed Dilute Flows Using the Continuum Approach","authors":"I. A. Kryukov,&nbsp;I. E. Ivanov","doi":"10.1134/S0015462825603948","DOIUrl":"10.1134/S0015462825603948","url":null,"abstract":"<p>A computational algorithm for calculating flows of nonequilibrium gas-dispersed media (gas–solid particles, gas–liquid droplets) with a low volume concentration of the dispersed phase has been developed. Within the Euler–Euler approach, a fully continuous description of the two-phase medium is implemented based on the mathematical model for two-phase flows by A. Chinnayya, R. Saurel, and Q. Carmouze (2016). The effect of pressure and phase velocity relaxation is taken into account during phase interaction. The computational algorithm utilizes the high-resolution Godunov method and HLL Riemann solver. The main focus is on accounting for the influence of phase velocity nonequilibrium (slip) on the relationship between the trajectories of particles and the gas phase, as well as on the interaction of the dispersed phase with solid walls. Test calculations are carried out in the case of a one-dimensional flow of a two-phase medium and methodological studies examining how the particle size and the dispersed-phase volume fraction affect the structure and parameters of gas-dispersed flows in two-dimensional regions bounded by solid surfaces.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 7","pages":""},"PeriodicalIF":0.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of the Influence of Atmospheric Air on the Active Medium of an Optically Pumped Rare Gas Laser","authors":"A. V. Juriev,&nbsp;Yu. A. Adamenkov,&nbsp;B. A. Vyskubenko,&nbsp;M. A. Gorbunov,&nbsp;A. A. Kalacheva,&nbsp;V. A. Shaidulina","doi":"10.1134/S0015462825603808","DOIUrl":"10.1134/S0015462825603808","url":null,"abstract":"<p>This paper presents a theoretical study of the influence of atmospheric air impurity on the active medium of an optically pumped rare gas laser. The active medium of the laser is formed by passing a pulse-periodic discharge through an argon–helium plasma and represents excited states of argon at the lower levels of the <i>s</i>- and <i>p</i>-multiplets. The analysis of key reactions of the interaction of nitrogen and oxygen particles with each other, with electrons, and with argon and helium atoms is carried out. The key reactions of interaction that have the greatest effect on the particle concentration are selected. A kinetic model of Ar–He plasma is compiled and the reactions of the interaction of inert-gas atoms with nitrogen and oxygen atoms, molecules, and ions are added. The concentration of excited argon atoms and other plasma particles is calculated. The calculation results demonstrate that when the proportion of impurity gases in the active medium of the laser exceeds 1 × 10⁻⁵, their effect on the concentration of excited argon and helium atoms and ions becomes noticeable. When the proportion reaches 5 × 10⁻⁴, the quenching of excited atoms due to collisions with nitrogen and oxygen begins to prevail over other quenching mechanisms.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 7","pages":""},"PeriodicalIF":0.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative Analysis of Heat-Transfer Efficiency in Round and Flat Continuous Diffusers","authors":"V. G. Lushchik,&nbsp;A. I. Reshmin,&nbsp;A. D. Chicherina","doi":"10.1134/S0015462825603870","DOIUrl":"10.1134/S0015462825603870","url":null,"abstract":"<p>Numerical simulation of flow and heat transfer in round and flat continuous diffusers with a smooth surface is performed using a three-parameter differential RANS turbulence model supplemented by a transfer equation for the turbulent heat flux. A comparative analysis of local and integral characteristics of the flow and heat transfer shows that, at the same opening angle, the Nusselt number in a round diffuser is higher than in a flat diffuser, and this excess increases with increasing opening angle. However, the Reynolds analogy factor for a round diffuser is slightly higher than for a flat diffuser due to the higher value of the friction coefficient in a round diffuser. It is shown that, with an increasing Reynolds number, the Reynolds analogy factor, both current and averaged over the diffuser length, slightly decreases. The Nusselt number averaged over the length also decreases, while the averaged friction coefficient remains practically constant.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 7","pages":""},"PeriodicalIF":0.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The PROCESS Database of Recommended Data in the AVOGADRO System: Recovered Data and Organization of Access","authors":"A. L. Sergievskaya,&nbsp;V. Yu. Levashov","doi":"10.1134/S0015462825603766","DOIUrl":"10.1134/S0015462825603766","url":null,"abstract":"<p>One of the main components of the AVOGADRO scientific information system—the database of recommended data on rate constants of chemical reactions—has been restored. The data are accompanied by expert commentaries with brief justifications for the recommendations and links to information sources. The basic data has an attribute of the degree of reliability and an expert numerical value of the error in various ranges of the argument of the gas medium (translational temperature). The new version of the database is implemented as an Excel file and is accompanied by a description of the structure and procedure for accessing the data. In total, data for 1384 chemical reactions are presented. The file is available for downloading to readers of the journal on the article page in the Media section (https://chemphys.edu.ru/issues/2025-26-5/articles/1191/#media). The database is intended for information support for mathematical modeling in physical and chemical kinetics.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 7","pages":""},"PeriodicalIF":0.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Spacing and Canting on Twinjet Characteristics","authors":"K. B. V. Satya Prakash,&nbsp;P. Lovaraju,&nbsp;E. Rathakrishnan","doi":"10.1134/S0015462825603134","DOIUrl":"10.1134/S0015462825603134","url":null,"abstract":"<p>The effect of the spacing between two centers of twin nozzles on the propagation of the Mach 0.8 twinjet is studied experimentally. The center-to-center spacings of the twin nozzles studied are equal to 3<i>D</i> and 5<i>D</i> (here, <i>D</i> is the nozzle exit diameter). The twinjets in parallel, inward and outward canting configurations are also studied. The inward and outward canting nozzles with a half angle of interception of 5°, 10°, and 15° are studied. For the inward canting, it is found that the peak Mach number is higher for the inward-canting twinjets than for the parallel and outward-canting twinjets. The interaction of twinjets diminishes with increase in the nozzle spacing.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 7","pages":""},"PeriodicalIF":0.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of the Hydrogen Blending Ratio on Leakage Diffusion and Explosion Range of Above-Ground Natural Gas Pipelines","authors":"L. Q. Chen,&nbsp;S. X. Li,&nbsp;J. T. Huang","doi":"10.1134/S0015462825601822","DOIUrl":"10.1134/S0015462825601822","url":null,"abstract":"<p>Hydrogen energy, as a clean and efficient secondary energy, has a broad application prospects under the global energy transition and carbon neutrality goals. Blending hydrogen into the natural gas pipeline is the most technologically viable and economically feasible approach for hydrogen transportation while resulting in more severe leakage consequences. The existing studies mainly focus on buried pipelines, while ignoring above-ground pipelines, which have a wider impact range due to the lack of soil resistance. In this study, the numerical simulation method is used to investigate the effect of the hydrogen blending ratio on leakage diffusion and explosion range of above-ground natural gas pipelines. The results show that the hydrogen blending ratio (HBR) has a small effect on the leakage diffusion range, but a significant effect on the explosion range and the leakage velocity. When the hydrogen blending ratio is less than 10%, the leakage diffusion range, the explosion range, and the leakage velocity are close to the natural gas condition. This study provide theoretical guidance for the selection of the hydrogen blending ratio for natural gas pipelines.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 7","pages":""},"PeriodicalIF":0.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of Turbulent Flow Characteristics in Plate Heat Exchangers with Diffuser Channels","authors":"V. G. Lushchik,&nbsp;A. I. Reshmin,&nbsp;A. D. Chicherina","doi":"10.1134/S0015462825603869","DOIUrl":"10.1134/S0015462825603869","url":null,"abstract":"<p>Numerical simulation of the flow and heat transfer in a unit of a counter-flow heat exchanger is carried out using a three-parameter differential RANS turbulence model supplemented by a transfer equation for a turbulent heat flow. The adjacent channels of the unit are flat, continuous diffusers with a smooth surface. The physical properties and thickness of the wall between the channels are taken into account. The analysis of the influence of the opening angle of the diffusers on the local and integral characteristics of the flow of hot and cold fluids, as well as heat exchange, shows that the intensity of turbulence and shear stress increase with an increase in the angle of inclination of the heat-transfer wall of the diffuser channel.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 7","pages":""},"PeriodicalIF":0.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147336961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mathematical Models of Spontaneous Rotation of Ice on the Surface of Water","authors":"T. O. Chaplina,&nbsp;V. P. Pakhnenko","doi":"10.1134/S0015462825603924","DOIUrl":"10.1134/S0015462825603924","url":null,"abstract":"<p>The results of theoretical and experimental studies of convective vortex flows formed during the melting of ice, as well as the physical and mathematical modeling of the phenomenon of spontaneous displacement and rotation of an ice disk on the surface of still water are presented. It is shown that the cause of the observed movements on the surface of initially still water is a cellular convective flow generated by the process of ice melting at the lower boundary of the disk, and a mathematical model of this rotation is constructed.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 7","pages":""},"PeriodicalIF":0.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147336962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}