Fluid Dynamics最新文献

{"title":"Diffraction of Oblique Surface Waves by an Ice Cover in the Presence of a Current with Velocity Shear","authors":"L. A. Tkacheva","doi":"10.1134/S0015462824604303","DOIUrl":"10.1134/S0015462824604303","url":null,"abstract":"<p>The diffraction of oblique surface waves on the edge of an elastic semi-infinite plate floating on the surface of a fluid of finite depth in the presence of a current with linear velocity shear is studied. An exact analytical solution of this problem is constructed using the Wiener–Hopf technique. The frequency dependences of the reflection and transmission coefficients and angles are investigated at various angles of incident waves and the shear gradient.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143938372","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":"Influence of the Mach Number on the Flow Field and Acoustics of a Supersonic Jet with Tabs","authors":"S. R. Lavala,&nbsp;S. Das","doi":"10.1134/S0015462824604741","DOIUrl":"10.1134/S0015462824604741","url":null,"abstract":"<p>Experimental investigations are carried out with triangular shaped tabs orientated circumferentially 120° apart with designed nozzle Mach numbers of 1.5, 2.0, and 2.5. The effects of the Mach number with a constant exit pressure ratio (EPR) of 0.35 and the constant nozzle pressure ratio (NPR) of 6 are studied. The Pitot survey and Schlieren flow visualization are carried out to present the jet core length characteristics, the shock cell structure, and the jet spread through time-averaged images. Acoustic measurements are made inside an anechoic chamber to get the signatures of various nozzle design Mach numbers. It is observed that the screech fundamental frequency shifts with increase in the design Mach numbers. The triangular shaped tabs can reduce the jet core length effectively to the tune of 40–70% in the ranges tested at various designed Mach numbers. The results indicate complete alleviation of noise/acoustics for jets adopting tabs having triangle shape irrespective of the penetration depth and orientation.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143938664","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":"Simulation and Experimental Study on Droplet Impact Rebound Behavior on Stainless Steel Surface","authors":"L. Yang,&nbsp;T. Y. Zhou,&nbsp;X. Y. Zhang","doi":"10.1134/S0015462824605497","DOIUrl":"10.1134/S0015462824605497","url":null,"abstract":"<p>The droplet impact rebound behavior is one of the most direct ways to study the hydrophobicity of materials. Different from the previous study, a series of groove structures with the same groove to the column ratio and the column height but various width sizes were constructed on the 316L stainless steel surface. The volume of fluid (VOF) method and experiments were used to observe the morphological evolution process of droplets impacting on the surface of this series of 316L stainless steel grooves at the same speed. The simulation and experimental data reveal that the grooved structure on 316L stainless steel surfaces markedly enhances the rebound coefficient of droplets and diminishes the spreading coefficient as compared to the smooth surface. The maximum rebound coefficient of the groove structure surface with the width of 100 μm increased the most by 2.093, the maximum spreading coefficient of the groove structure surface with a width of 200 μm decreased the best by 0.805, indicating that the establishment of groove structures significantly improves hydrophobicity. At the same time, as the groove width increases from 50 to 300 μm, the wetting state of droplets on the stainless steel groove surface gradually changes from the Cassie Baxter state to the Wenzel state, and the rebound coefficient decreases with transformation of the wetting state, but the spreading coefficient is not affected transformation of the wetting state.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143938378","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":"Thermal Effect on Dynamic Evolution of Cavitation Flows through a Cryogenic Butterfly Valve","authors":"G. Zhang,&nbsp;K. Wang,&nbsp;W. W. Wang,&nbsp;D. S. Chen,&nbsp;Z. Lin","doi":"10.1134/S0015462824604418","DOIUrl":"10.1134/S0015462824604418","url":null,"abstract":"<p>In cryogenic butterfly valves, the obstruction caused by the valve core leads to the localized pressure drop in flow of cryogenic media. This cavitation phenomenon is induced when the localized pressure of the cryogenic medium falls below the saturation vapor pressure corresponding to the local temperature. In comparison to the fluid medium with normal temperature, the thermal sensitivity of cryogenic media affects the precision of the numerical simulations for cavitation flow fields at cryogenic conditions when employing conventional cavitation models. In this study, the traditional Zwart–Gerber–Belamri (ZGB) cavitation model is modified by considering the thermal effect of cryogenic medium. A modified cavitation model is obtained to accurately predict cryogenic cavitation flows and verified by experimental results. By utilizing the modified cavitation model and large eddy simulation model, the cavitation flow field and the cavitation evolution of liquid nitrogen through a cryogenic butterfly valve was studied at various temperatures and the valve opening degree of 80%. Using the ω-criterion, the spatial and temporal correlations between the cavitation and vortex structures are discussed and analyzed in detail.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143938613","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 Study of the Turbulent Boundary Layer with an Adverse Pressure Gradient in Compressible Gas Flow","authors":"V. G. Lushchik,&nbsp;S. S. Popovich","doi":"10.1134/S0015462824604583","DOIUrl":"10.1134/S0015462824604583","url":null,"abstract":"<p>The turbulent boundary layer in supersonic flow with an adverse pressure gradient is numerically simulated using the three-parameter differential RANS turbulence model. The adverse pressure gradient is implemented by reducing the Mach number along the plate. The simulation is carried out for a number of values of the free-stream Mach number from 1.5 to 3.0 and the temperature factor equal to and different from unity. The results of calculating the integral and local flow characteristics testify that there is a significant effect of the adverse pressure gradient on the flow and heat transfer characteristics.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143925657","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 Analysis of Gas–Liquid Flow Characteristics in Annular Microreactors","authors":"J. Y. Bai,&nbsp;P. Yan,&nbsp;H. B. Jin,&nbsp;S. H. Yang,&nbsp;G. X. He,&nbsp;L. Ma","doi":"10.1134/S001546282460439X","DOIUrl":"10.1134/S001546282460439X","url":null,"abstract":"<p>The characteristics of two-phase gas–liquid flow within annular microreactors are investigated using the volume of fluid method implemented in Fluent. The analysis encompasses the annular gap sizes of 0.25, 0.5, and 1.0 mm. The effects of the fluid velocity, the annular gap size, the initial gas holdup, and the fluid viscosity on the flow patterns, the gas holdup, and the pressure drop are discussed and compared with experimental results. Based on the simulation results, flow pattern maps within the annular microchannel are generated, showing a good agreement with the experimental data reported in the literature. In addition, a pressure drop model for two-phase flow within the microreactor is developed, and the correlation for the model parameters is revised. The simulations reveal that the Taylor-flow regime appears at the lower flow rates in narrower annular gaps. Moreover, the pressure drop increases with the fluid velocity, with the liquid phase exerting a significantly greater impact than the gas phase. Furthermore, the increased surface tension accelerates bubble coalescence.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143925658","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":"Investigations on a Supersonic Combustor with Ramps and Cavities for Sustained Combustion","authors":"G. Amba Prasad Rao,&nbsp;J.V.S. Moorthy","doi":"10.1134/S0015462824605436","DOIUrl":"10.1134/S0015462824605436","url":null,"abstract":"<p>The ignition process in supersonic flows is complex, influenced by the fuel ratios, design, and flow conditions. The cavity combustors stabilize regions for ignition, whereas ramps aid in mixing fuel and air. The shock waves generated by these ramps interact with the fuel stream, enhancing micro-mixing and creating recirculation zones to improve fuel-air mixing. In supersonic flow, these vortices contribute to macro-mixing, while the interaction between shocks and the fuel stream generates boroclinic torque at the air-fuel interface, further improving micromixing. A full-scale experimental combustor facility is designed and tests are done on a supersonic combustor incorporated with ramps and cavities, using aviation kerosene. The combustor wall pressures and temperatures are obtained using the instrumentation. Numerical studies examined the effects of the Mach number on flow. ANSYS-based simulations revealed that the combustor configuration and the Mach number play a vital role. It is inferred that a staged injection improves mixing and thrust. At a combustor entry Mach number equal to 2, in the diverging section the static pressures initially rise, then decrease with time, indicating supersonic combustion, with a wall pressure increase of about 1.3 bar the exit static pressures rise to equalize with ambient conditions. The adopted strategies resulted in sustained supersonic combustion.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143925660","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":"CFD Analysis of Weapon Bay Missile Ejection at Various Mach Numbers","authors":"P. Tembhurnikar,&nbsp;MD. G. Sarwar,&nbsp;D. Sahoo","doi":"10.1134/S0015462824605333","DOIUrl":"10.1134/S0015462824605333","url":null,"abstract":"<p>The aerodynamic behaviour of missiles released from weapon bay cavities at supersonic velocities ranging from Mach 2 to Mach 5 is studied. The computation offers detailed examinations of the pressure fluctuations, the density variations, and the Mach number distributions. A particular attention is focused on the interaction of the shear layer at the leading edge of the cavity with the shock generated on the missile nose. The findings indicate minimal changes in the interaction between the shear layer at the cavity’s leading edge and the leading-edge shock produced at the missile’s nose at the Mach number range from 2 to 5. At the Mach number equal to 2, the interaction is relatively subdued, mainly affected by a detached shock wave with increased flow turning angle. Prandtl–Meyer expansion on both the nose tip and the tail end of the missile highlights the influence of compressibility. In contrast, at the Mach numbers equal to 3, 4, and 5, the interaction between the shear layer and the shock wave system becomes a notable factor that affects aerodynamic changes. In contrast, an intense detached bow shock wave prevails at the Mach number equal to 2. These findings offer crucial insights into the intricate flow dynamics surrounding missiles at high supersonic velocities, with implications for enhancing aerodynamic design and optimizing performance in future aerospace endeavours.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143925659","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":"Method of Temperature Correlations for Estimating the Large-Scale Circulation Rate in the Case of Turbulent Convection of Liquid Metals in an Inclined Cylinder","authors":"A. D. Mamykin","doi":"10.1134/S0015462824604376","DOIUrl":"10.1134/S0015462824604376","url":null,"abstract":"<p>The potentials of the temperature correlation method in determining the mean velocities of liquid metal turbulent flows are investigated. The method uses the signals from temperature sensors arranged in line in the direction of large-scale circulation motion. As distinct from other, more conventional techniques, this indirect method can be used in the measurements in melt metals, which represent aggressive opaque media. The method is based on the Taylor hypothesis of the temperature disturbance field freezing in the velocity field on a certain level of flow turbulence. By fixing the passage of such disturbances through temperature sensors it is possible to calculate the flow velocity. The flow in the actual setups is usually inhomogeneous and developed turbulence arises only locally in the cavity. For this reason, though the method is absolute and does not need calibration, its applicability should to be verified in each particular case. In this study the method is applied to the problem of turbulent convection of liquid sodium (Prandtl number Pr = 0.0083) in a cylinder, whose length is greater than its diameter by the factor of 5, heated from one end and cooled from the other. In the flow regimes considered the cylinder is inclined to the vertical by an angle β, 18° ≤ β ≤ 90°. The Rayleigh number based on the cylinder diameter was 5 × 10⁶. An analysis of the data of experimental investigations and three-dimensional numerical calculations is performed. In the latter case the flow velocity is known for a fact and can be directly compared with the estimates obtained using the cross-correlation analysis. It is shown that the method of temperature correlations not always allows one to adequately estimate the mean velocities of regular large-scale sodium flows, that is, has its own restrictions. The method performs well in the conditions of moderate turbulent fluctuations of the temperature and velocity. The greatest error of the method takes place near the heat exchangers in the flow direction: a demonstrative explanation of the reasons for this error is proposed with reference to this example. The nonlinear dependence of the large-scale circulation amplitude on the angle of inclination of the cylinder is obtained; it has a maximum near 45°. The location of the maximum of this dependence is different from that for the cylinder with the aspect ratio 20 (60°–70°).</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143925618","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":"Stimulation of Thrombus Dissolving by Magneto-Induced Circulation Currents","authors":"A. Yu. Musikhin,&nbsp;A. Yu. Zubarev","doi":"10.1134/S0015462824603711","DOIUrl":"10.1134/S0015462824603711","url":null,"abstract":"<p>The theoretical model and the method of its approximate analysis dealing with flows induced by a rotating magnetic field in the channel occupied by a non-magnetic fluid with an embedded ferrofluid layer are proposed. One of the channel ends is assumed to be closed (thrombotic). Some estimates of the velocity of convective-diffusion flow of a neutral impurity (thrombolytic) onto a thrombus in the channel with magnetically induced circulation currents are obtained and the effect of these currents on the thrombus dissolution rate is studied.</p>","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143925661","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}