European Journal of Mechanics B-fluids最新文献

{"title":"Deformable droplet under Poiseuille flow: Role of flow direction, channel inclination and off-centre dynamics","authors":"Shubham Lanjewar,&nbsp;Sundari Ramji","doi":"10.1016/j.euromechflu.2024.12.005","DOIUrl":"10.1016/j.euromechflu.2024.12.005","url":null,"abstract":"<div><div>The dynamics of a confined, deformable droplet with an imposed external flow (upward, quiescent and downward) is numerically investigated using an in-house solver based on the Level Set method. This is the first comprehensive investigation unravelling (i) the oscillatory dynamics of an off-centered droplet under an external flow, (ii) the hydrodynamics of a droplet subjected to a downward flow, and (iii) the effect of channel orientation. Both co-current and counter-current droplet motions are explored. While a freely falling initially off-centered droplet demonstrates an oscillatory trajectory with significant shape deformation, we show that an imposed downward flow dampens the oscillations and minimizes deformation resulting in a greater terminal speed of the droplet. Conversely, an upward, counter-current flow causes greater droplet deformation with increased oscillations. Moreover, reducing the channel inclination leads to asymmetric droplet shapes with uneven film thickness on either side of the channel and a higher residence time. The other key findings include (i) transition from convex to concave droplet tail in both upward and downward flows, dictated by the strength of external flow and <span><math><mi>Bo</mi></math></span>. (ii) Formation of a streamlined droplet accompanied by an increase in the film thickness on increasing viscosity ratio in both co-current and counter-current droplet flows and (iii) the generation of novel flow maps in the density ratio - pressure drop parameter space delineating three distinct regions: downward sinking, upward rising, and stationary droplet, depending on the relative strength of buoyancy and external flow.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"111 ","pages":"Pages 100-112"},"PeriodicalIF":2.5,"publicationDate":"2024-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143102375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A mathematical model for viscous flow dynamics of tropical cyclones","authors":"Sanjay Kumar Pandey,&nbsp;Kriti Yadav","doi":"10.1016/j.euromechflu.2024.12.003","DOIUrl":"10.1016/j.euromechflu.2024.12.003","url":null,"abstract":"<div><div>A mathematical model for tropical cyclones’ winds, taking into account various crucial considerations makes the analysis of Cecil and Majdalani (2022) more realistic. Drawing inspiration from their work which obtains the axial velocity from the stream function, we incorporate the notion of viscous flow within cyclone dynamics, a modification that brings present model more closely aligned with the real-world conditions. Our key considerations include the absence of axial velocity at the ground, zero radial velocity at the cyclone’s centre, and outside the eye-wall. In order to derive pressure, we integrate axial pressure gradient with respect to axial coordinate; and as a consequence we get an arbitrary function of radial coordinate which we eliminate by using Vatistas (1991) velocity at the ground to meet the cyclostrophic balance. Azimuthal velocity and pressure are derived for viscous flows. The formulations hold good for arbitrary Reynolds number. The analysis demonstrates a positive relationship between Reynolds number and azimuthal velocity within cyclone’s eye. This trend persists within the inner eye-wall, characterized by a gradually diminishing velocity. An inflexion point is identified midway the eye and the eye-wall, where maximum azimuthal velocities are observed. The central focus of our study revolves around the influence of eye size on various velocity components and pressure. Our findings reveal that a larger eye size correlates with the development of more intense tropical storms. However, this increase in storm intensity reaches a peak and subsequently experiences a rapid decline within the rain band region compared to smaller eye cyclones. Regardless of the eye’s size, our analysis consistently demonstrates that atmospheric pressure increases as one moves away from the eye.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"111 ","pages":"Pages 72-80"},"PeriodicalIF":2.5,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143102331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 investigation of the role of human motion in the spread of virus-laden droplets from coughing using CFD dynamic mesh technique","authors":"Sadegh Sadeghi,&nbsp;Saiied M. Aminossadati,&nbsp;Christopher Leonardi","doi":"10.1016/j.euromechflu.2024.12.002","DOIUrl":"10.1016/j.euromechflu.2024.12.002","url":null,"abstract":"<div><div>The transmission of viruses through the air plays a crucial role in the spread of viral diseases in enclosed environments. The mobility of individuals is a potential factor that contributes to the increment of the propagation of respiratory infections through the air. This research comprehensively focuses on transient modelling of the spread of solid-containing droplets during a cough from a moving person inside a ventilated room through CFD approach. This study investigates a range of moving speeds, from 0 to 1.5 m/s, to illustrate differences in patterns and concentration of droplets during both mobile and stationary conditions of an individual considering the interactions among gas, liquid and solid phases. Interactions between phases are considered through a coupled Eulerian–Lagrangian approach, and discrete phase model (DPM), turbulence model, species transport model, evaporation model and dynamic mesh technique are integrated. Moreover, the influences of effective forces such as buoyancy, Brownian motion, drag, lift, and gravitational forces are included. Regarding the results, motion of individuals significantly affects the airflow pattern and dispersion of droplets, particularly for walking speeds of more than 1 m/s. The results also elaborately indicate that person’s movement (from 0 to 1.5 m/s) considerably enhances the turbulent intensity (about 40 %), average air velocity and oscillations in pressure distribution, especially, pressure gradient before and after the moving person (about 1.5 Pa). Additionally, when the person walks at speeds exceeding 1 m/s, most of the particles cannot attach to the person’s body due to insufficient time for settling, resulting in an increment in the total number of particles that remain suspended in the air.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"111 ","pages":"Pages 42-60"},"PeriodicalIF":2.5,"publicationDate":"2024-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143102329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A discrete Immersed Boundary Method for the numerical simulation of heat transfer in compressible flows","authors":"H. Riahi ,&nbsp;P. Errante ,&nbsp;E. Goncalves da Silva ,&nbsp;M. Meldi","doi":"10.1016/j.euromechflu.2024.12.001","DOIUrl":"10.1016/j.euromechflu.2024.12.001","url":null,"abstract":"<div><div>In the present study, a discrete forcing Immersed Boundary Method (IBM) is proposed for the numerical simulation of high-speed flow problems including heat exchange. This class of tools is relevant for several applications in engineering studies for aerospace applications, notably for atmospheric reentry. The flow field is governed by the compressible Navier–Stokes equations, which are resolved by using the open source library OpenFOAM. The numerical solver is modified to include source terms in the momentum equation and in the energy equation, which account for the presence of the immersed body. The method is validated on some benchmark test cases dealing with forced convection problems and moving immersed bodies. The results obtained are in very good agreement with data provided in the literature. The method is further assessed by investigating three-dimensional high Mach flows around a heated sphere with different wall temperature. Even for this more complex test case, the method provides an accurate representation of both thermal and velocity fields.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"111 ","pages":"Pages 61-71"},"PeriodicalIF":2.5,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143102330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Filler advert: scival_2021_210x280.pdf","authors":"","doi":"10.1016/S0997-7546(24)00179-1","DOIUrl":"10.1016/S0997-7546(24)00179-1","url":null,"abstract":"","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"110 ","pages":"Page I"},"PeriodicalIF":2.5,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143149422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 turbulent high-speed flow over the double wedge at varying aft-wedge deflections","authors":"Anurag Adityanarayan Ray ,&nbsp;Ashoke De","doi":"10.1016/j.euromechflu.2024.11.012","DOIUrl":"10.1016/j.euromechflu.2024.11.012","url":null,"abstract":"<div><div>This study examines the shock–shock (SSI) and shock-wave boundary layer (SBLI) interaction mechanisms over the two-dimensional double wedge exposed to hypersonic Mach 5 flow. Several Unsteady Reynolds-averaged Navier Stokes (URANS) based turbulence models are used systematically to determine the most suitable model. Grid sensitivity analysis indicates that while the laminar model is sensitive to grid size, turbulent models exhibit grid independence, suggesting the laminar model’s unsuitability under these conditions. We further support this hypothesis by a qualitative and quantitative comparison of the numerical schlieren images and mean wall heat flux profiles, respectively, with the experimental results. The average heat flux based on the fully laminar assumption provides accurate predictions in the well-attached flow region, but it fails horribly after the SBLI interaction. The models using the standard <span><math><mrow><mi>k</mi><mo>−</mo><mi>ω</mi></mrow></math></span> SST (shear stress transport) turbulence model and the four-equation Lantry–Menter correlation-based model consistently overpredict the wall heat transfer rate throughout the double-wedge surface. The newly employed Krause correlations significantly improve the match with the qualitative and quantitative experimental observations. This article further uses this novel turbulence model to explore the impact of the aft-wedge angle variation (<span><math><mrow><mn>4</mn><msup><mrow><mn>5</mn></mrow><mrow><mn>0</mn></mrow></msup><mo>≤</mo><msub><mrow><mi>θ</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>≤</mo><mn>6</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>0</mn></mrow></msup></mrow></math></span>) on the shock–shock interaction mechanisms and the associated wall properties. Results indicate a weak Edney type-V interaction at the lowest angle, transitioning to Edney type-V with Mach reflection for <span><math><mrow><msub><mrow><mi>θ</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>≥</mo><mn>5</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>0</mn></mrow></msup></mrow></math></span>. Hence, the critical transition aft-wedge angle concerning the change in the shock interference pattern is between <span><math><mrow><msub><mrow><mi>θ</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>=</mo><mn>4</mn><msup><mrow><mn>5</mn></mrow><mrow><mn>0</mn></mrow></msup></mrow></math></span> and <span><math><mrow><msub><mrow><mi>θ</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>=</mo><mn>5</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>0</mn></mrow></msup></mrow></math></span>.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"111 ","pages":"Pages 20-41"},"PeriodicalIF":2.5,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143093202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flow topology of the wake of a rotor and its relationship with the energy efficiency","authors":"A.C. Espinosa Ramírez,&nbsp;Oscar Velasco Fuentes","doi":"10.1016/j.euromechflu.2024.11.010","DOIUrl":"10.1016/j.euromechflu.2024.11.010","url":null,"abstract":"<div><div>A numerical model is used to study the flow in the wake of a two-bladed horizontal-axis rotor. The flow topology is analyzed for three different angular velocities of the rotor. For the fastest rotor there is a region downstream where the fluid loses nearly 30% of the axial inflow velocity, whereas almost 60% is lost if this region belongs to the wake of a second-in-line rotor. The second part of this study deals with the evolution of the tip helical vortices in the presence of a turbulent inflow wind. This is found to destabilize the vortices, which subsequently perform a leapfrogging motion. As the turbulence of the inflow wind strengthens, the leapfrogging starts closer to the wind rotor. If a second-in-line rotor is located in this wake, the power it extracts from the wind depends on its location with respect to the point where the first rotor’s vortices become unstable. A second rotor located downstream of this point extracts more power than one located upstream of this point.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"111 ","pages":"Pages 1-10"},"PeriodicalIF":2.5,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143102376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Free-surface flow due to a line source near a vertical barrier","authors":"W.F. Mansoor ,&nbsp;G.C. Hocking","doi":"10.1016/j.euromechflu.2024.11.011","DOIUrl":"10.1016/j.euromechflu.2024.11.011","url":null,"abstract":"<div><div>The unsteady flow generated by a line source that is located at an arbitrary location beneath the free surface of a fluid of finite depth is considered when there is vertical barrier located nearby. The surface may have surface tension. The barrier is shown to have a significant effect on the wave height generated at the barrier and the outward travelling bore generated by the initiation of the flow. Simulations of free surface flows are very difficult due to the formation of curvature singularities on the surface. The method employed in this work does not appear to have these difficulties and the solutions can be computed almost up until the moment the wave breaks, including in some cases a significant spill at the front. A linearized solution and a fully nonlinear solution are presented and the results compared and discussed.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"111 ","pages":"Pages 11-19"},"PeriodicalIF":2.5,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143093201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Suppression of rankine vortex formation in liquid draining tanks: A critical review","authors":"Mahadev Prabhu,&nbsp;C.M. Hariprasad,&nbsp;R. Ajith Kumar","doi":"10.1016/j.euromechflu.2024.11.009","DOIUrl":"10.1016/j.euromechflu.2024.11.009","url":null,"abstract":"<div><div>Air-core vortexing phenomenon during draining of liquids from cylindrical vessels is of major interest because this phenomenon has significant impact in multiple engineering systems. The adverse effects created by vortex formation via air-core ingestion in the field of aerospace engineering, metal casting and hydraulic engineering demanded the need for air-core vortex suppression. From past few decades, researchers have come up with unique strategies to suppress vortexing phenomenon. As the first ever initiative, the current review classifies all the strategies reported in the literature and addresses the advantages and adverse effects of each strategy. Based on this classification, this review identifies vortex suppression strategies suitable for various engineering applications. The present review also investigates the contradictions and misinterpretations observed in the published results. Research gaps and major outcomes identified in this review are novel and are expected to give a fresh impetus for further research delivering new insights on the phenomenon of air core vortex formation aiding to develop new suppression strategies.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"110 ","pages":"Pages 34-64"},"PeriodicalIF":2.5,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamics of a compound droplet in a microchannel containing a long obstacle","authors":"Nang X. Ho,&nbsp;Vinh T. Nguyen,&nbsp;Hoe D. Nguyen,&nbsp;Truong V. Vu","doi":"10.1016/j.euromechflu.2024.11.008","DOIUrl":"10.1016/j.euromechflu.2024.11.008","url":null,"abstract":"<div><div>In this work, we numerically analyze the breakup process of a two-dimensional compound droplet as it moves through a microchannel and encounters an obstacle embedded in it. Initially, the droplet is circular and concentric, and positioned near the inlet of the main channel. Under the influence of the inflow, the droplet moves toward the head of the obstacle, which has a semicircular shape. At a certain moment, the droplet and the obstacle interact with each other. With this interaction, simple daughter droplets and compound daughter droplets can be generated from the original droplet due to changes in the obstacle size, the inner droplet size, and especially the variation in surface tension described by the Weber number. The results reveal that with larger Weber numbers and smaller radii of the inner droplet and the obstacle, the compound droplet is completely separated. Based on the influence of these parameters, a phase diagram for the problem is constructed.</div></div>","PeriodicalId":11985,"journal":{"name":"European Journal of Mechanics B-fluids","volume":"110 ","pages":"Pages 25-33"},"PeriodicalIF":2.5,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}