Experiments in Fluids最新文献

{"title":"Noise control in tandem airfoil configurations using leading-edge serrations on the front airfoil","authors":"Xishuai Yu,&nbsp;Jianxi Zhou,&nbsp;Yong Li","doi":"10.1007/s00348-025-04033-w","DOIUrl":"10.1007/s00348-025-04033-w","url":null,"abstract":"<div><p>Passive noise control of a tandem NACA6412 airfoil is experimentally studied by applying sinusoidal serrations to the leading-edge of the front airfoil. The position of the rear airfoil in the vertical gap direction is adjusted to identify the position that results in the maximum reduction in far-field noise. Subsequently, detailed unsteady flow characteristics in the flow field are measured using particle image velocimetry (PIV). The far-field noise results indicate that, at the position of optimal noise reduction, the application of leading-edge serrations to the front airfoil significantly reduces turbulence interaction noise in the frequency range of <span>(text{700 }text{Hz} le fle {2000} text{Hz})</span>, with a maximum reduction of up to 10 dB. Analysis of the PIV results shows that leading-edge serrations can significantly decrease turbulence intensity and vorticity in the wake of the front airfoil, while also narrowing the influence range of vortex shedding and turbulence. Therefore, the positioning of the front and rear airfoils has a strong impact on the variation in turbulence interaction noise. The research concludes by emphasizing the effect of leading-edge serrations on the wake of airfoils. These findings can be applied to reduce noise in rotating machinery, such as guide blade rows, fan blade rows, and turbine blade rows.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 5","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143918994","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":"Measurement of quantitative heat flux on translucent surfaces using infrared thermography","authors":"Brian S. Kinsey,&nbsp;James A. S. Threadgill,&nbsp;Stuart A. Craig","doi":"10.1007/s00348-025-04030-z","DOIUrl":"10.1007/s00348-025-04030-z","url":null,"abstract":"<div><p>A general algorithm is presented for determining accurate surface temperatures and heat transfer measurements using infrared thermography on optically translucent materials. The algorithm is validated with experimental data collected on a additively manufactured hemisphere made of Formlabs Rigid 10K in the University of Arizona Mach 5 Ludwieg tube. The accuracy of the measurement was determined by comparing to independent heat transfer sensors within the model and theoretical heating models. The results show significantly improved accuracy when compared to measurements made with the opaque body assumption which substantially underestimates the surface temperature and heat flux.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 5","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143896738","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":"Complete solid-body rotation rate measurements of micro-plastic curved fibers in turbulence","authors":"Giuseppe C. A. Caridi,&nbsp;Vlad Giurgiu,&nbsp;Marco De Paoli,&nbsp;Alfredo Soldati","doi":"10.1007/s00348-025-04021-0","DOIUrl":"10.1007/s00348-025-04021-0","url":null,"abstract":"<p>In this study we quantify the uncertainty relative to a novel Lagrangian tracking technique to measure the complete solid-body rotation rate of anisotropic micro-plastic fibers. By exploiting their geometry—specifically, their elongation and curvature for tumbling and spinning rate measurements, respectively—we address a gap in the literature regarding the tracking of fibers’ unique orientation along their trajectories. The impact of fiber geometry and imaging parameters on the accuracy of the solid-body rotation rates measurements is investigated. The influence of spatial and temporal resolution on the measurement uncertainty is assessed on synthetic data. Experimental results obtained in a channel flow demonstrate the method’s potential to accurately detect rotations of fibers with lengths approaching the Kolmogorov scale.</p>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 5","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-025-04021-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143900713","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":"Assessing the haemodynamics of the cerebral venous system anatomy in multiple sclerosis and a healthy control using in vivo and 3D printed in vitro modelling","authors":"Alexander Robert Bateman,&nbsp;Jeannette Lechner-Scott,&nbsp;Tracie Barber,&nbsp;Grant Alexander Bateman,&nbsp;Saadallah Ramadan,&nbsp;Shiami Luchow,&nbsp;Pujith Vijayaratnam","doi":"10.1007/s00348-025-04028-7","DOIUrl":"10.1007/s00348-025-04028-7","url":null,"abstract":"<div><p>This study aimed to compare computational fluid dynamics (CFD) results to those acquired in vivo with 4D Flow magnetic resonance imaging (MRI) and in vitro with a 3D printed model using pressure catheter manometry. The goal was to investigate the haemodynamics of the cerebral venous system (CVS) and assess the accuracy of the methodologies, to highlight any discrepancies between the techniques. One participant living with multiple sclerosis (MS) and one healthy control were recruited for this study. MRI was performed to generate 3D geometries of the anatomy and to compute blood flow rates at the boundaries, with 4D Flow MRI velocity streamlines for the control participant. CFD models were created for the two participants and simulated using the patient-specific boundary conditions. A 3D printed geometry of the MS participant was created and a flow loop experiment was conducted to measure the cerebral venous pressures. The venous pressures were found to be comparable to that observed in the CFD simulation. 4D Flow MRI velocity streamlines of the CVS were found to correspond well to the CFD findings, except for a few regions, which were likely impacted by the low resolution of the MRI. The use of all three methods enabled the successful validation of the velocity, flow features and pressure, and ensured that the haemodynamics of the CVS as resolved using CFD, were accurate. This highlights the potential for increased efficacy of the clinical outcomes of future studies that utilise such methods.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 5","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-025-04028-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143892674","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":"Exploring separation and reattachment in shear-thinning suspensions through pipe-wall ultrasound measurements","authors":"Giuseppe Rosi,&nbsp;Moira Barnes,&nbsp;Frieder Kaiser,&nbsp;David Rival","doi":"10.1007/s00348-025-04018-9","DOIUrl":"10.1007/s00348-025-04018-9","url":null,"abstract":"<div><p>To better understand how turbulent flow structures develop within shear-thinning suspensions (STSs), we investigate the behavior of a shear layer forming within an STS downstream of a sudden expansion with an expansion ratio of 0.5. Specifically, the shear-layer reattachment behavior downstream of an axisymmetric expansion is characterized through ultrasound imaging velocimetry (UIV) and through pressure measurements, and the observed behavior is used to surmise how the shear layer is modified within the STS. Four fluids are investigated, which include pure water, as well as three 1750 ppm xanthan-gum-in-water solutions mixed with non-reactive mineral microspheres at volume fractions of 0%, 15%, and 30%. Wall-pressure measurements were collected through pressure taps located at 0<i>h</i> to 25.8<i>h</i> downstream of the expansion with subsequent UIV measurements collected from 1<i>h</i> to 9<i>h</i> downstream of the expansion, where <i>h</i> is the step height and equals the difference between the pipe and throat radii. For single-phase cases, pressure-recovery profiles and UIV flow fields indicate a predictably large reattachment length at low Reynolds numbers, which shortens as the Reynolds number increases from <span>(O(10^2))</span> to <span>({O}(10^4))</span> and finally stabilizes at roughly 8<i>h</i>. In contrast, the STSs exhibit pressure-recovery and pipe-wall velocity profiles indicating a reattachment length that is consistently short (8<i>h</i>) and independent of Reynolds number. The results indicate that the suspended phase within the STSs causes the shear layer to diffuse far more rapidly, thereby promoting momentum transfer toward the wall, which results in a consistently short reattachment length.</p><h3>Graphic abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 5","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-025-04018-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143892675","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":"Experimental study on bubble pairs and induced flow fields using tomographic particle image velocimetry","authors":"Hanbin Wang,&nbsp;Yang Xu,&nbsp;Jinjun Wang","doi":"10.1007/s00348-025-04026-9","DOIUrl":"10.1007/s00348-025-04026-9","url":null,"abstract":"<div><p>Owing to their unique fluid dynamics, gas‒liquid two-phase flows, such as bubbly flows, are widely used in various engineering applications. This study utilized three-dimensional shadow image reconstruction (3D-SIR) and laser-induced fluorescence tomographic particle image velocimetry (LIF-TPIV) to perform a quantitative analysis of the three-dimensional morphology and motion of bubbles, as well as bubble-induced flow fields. By systematically varying the orifice spacing (<span>(s/{D}_{n})</span>, where <span>({D}_{n})</span> is the orifice inner diameter) among the values 3.3, 5, 6.7, and 8.3, we investigate the effects of distance on bubble interactions and flow dynamics. Our findings reveal that at <span>(s/{D}_{n})</span> = 3.3, the bubbles move very close to each other while rising. Distinct vortex rings form around each bubble near the orifice and merge as they rise, which increases flow transport, dissipation, and flow velocity between bubbles, leading to earlier bubble instability. Spectral analysis indicates that bubble spacing is coupled with the dominant flow frequency. As orifice spacing increases, bubble interactions weaken, resulting in independent vortex rings near the orifice that grow to approximately twice the bubble’s diameter before shedding secondary vortices. In these cases, regions of strong transport and dissipation are concentrated in the wake, and the flow velocity between bubbles remains relatively weak. Bubble instability primarily originates from the wake vortices. The aspect ratios of the bubbles align with the dominant flow frequency, indicating a coupling between flow dynamics and bubble morphology, although periodicity in bubble spacing weakens at larger spacings. These findings provide valuable insights into two-phase flow dynamics, especially in multiorifice bubbly flows. </p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 5","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143883609","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":"Impact of a core–shell compound droplet on a solid surface","authors":"I. Alkomy,&nbsp;M. Marengo,&nbsp;A. Amirfazli","doi":"10.1007/s00348-025-04022-z","DOIUrl":"10.1007/s00348-025-04022-z","url":null,"abstract":"<div><p>Droplet impact on solid surfaces is fundamental to many natural and industrial processes, from water distribution in agriculture to precision technologies like inkjet printing and fuel injection. Recent studies have increasingly focused on the complex dynamics of multi-component, core–shell droplets, driven by their widespread presence in fields such as targeted drug delivery, biofuels, and 3D printing. Understanding the outcome of the impact of compound droplets and their maximum spreading on a solid surface is needed. This research investigates the influence of the controlling parameters, namely a broad range of core size, the core and shell viscosities, and Weber number on the impact outcome and the maximum spreading. Experiments of water-in-oil compound drops impacting on glass surface were conducted up to the range of impact parameters below splashing threshold. An equivalent Weber number (<span>(overline{text{We} })</span>) was introduced to account for the core–shell interfacial energy. Results reveal that the size of the core and the viscosity of the shell play critical roles in determining impact behavior. Larger cores tend to enhance prompt splashing and rebound, while thicker shells dampen the rebound of the vertical jet formed by the core. Viscous cores significantly damped the rebound while had no influence on splashing. The maximum spreading factor is vastly affected by the shell layer viscosity rather than the core’s. The size of the core influences the maximum spreading in two different ways, varying the compound drop viscosity and increasing the core–shell interface. A quantitative framework for compound droplets impact on solid surfaces is established, focusing on impact outcome and maximum spreading. Distinct outcome regime boundaries and transitions are mapped within the parameter space of controlling parameters, while their influence and controllability on maximum spreading are systematically evaluated.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 5","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143871313","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":"Synthetic jet vortex rings impinging onto porous walls: a more comprehensive similarity parameter","authors":"Yang Xu,&nbsp;Haocheng Wang,&nbsp;Congyi Xu,&nbsp;Zhiyu Li,&nbsp;Jinjun Wang","doi":"10.1007/s00348-025-04023-y","DOIUrl":"10.1007/s00348-025-04023-y","url":null,"abstract":"<div><p>By combining the effects of synthetic jet Reynolds number (<i>Re</i>_<i>sj</i>), porous wall porosity (<i>ϕ</i>) and porous wall hole diameter (d_<i>h</i>*), Li et al. (AIAA J 58:722–732, 2020) and Xu et al. (Phys Fluids 33:035140, 2021) presented a dimensionless similarity parameter [(<i>Re</i>_<i>sj</i>²<i>d* </i>_<i>h</i>³)^<i>ϕ</i>] to characterize the interaction between synthetic jet vortex rings and a porous wall. To futher incorporate the jet-exit-to-wall distance (<i>H</i>^*) into this similarity parameter, an experimental study was conducted to inverstigate the effect of the jet-exit-to-wall distance (<i>H</i>^* = 2, 4, 6, and 8) on the impingement of synthetic jet vortex rings onto a porous wall under three Reynolds numbers (<i>Re</i>_<i>sj</i> = 300, 600, and 900). By establishing the relationship between the loss of jet momentum flux and the jet-exit-to-wall distance (<i>H</i>^*) at different <i>Re</i>_<i>sj</i>, a more comprehensive similarity parameter [(<i>Re</i>_<i>sj</i>²<i>d</i>_<i>h</i>^<i>*</i>3<i>H</i>^*−0.64)^<i>ϕ</i>] was derived to characterize this vortex rings-porous wall interaction. Given the substantial impact of <i>H</i>^* on the vortex ring strength upon the impingement, an effective interaction velocity (<i>V</i>_<i>j,eff</i> = <i>V</i>_<i>j</i>/<i>H</i>^*0.32±0.045, <i>V</i>_<i>j</i> is the characteristic velocity of the synthetic jet) was introduced, so that [(<i>Re</i>_<i>sj</i>²<i>d</i>_<i>h</i>^<i>*</i>3<i>H</i>^*−0.64)^<i>ϕ</i>] was transformed as [(<i>Re</i>_<i>eff</i>²<i>d</i>_<i>h</i>^<i>*</i>)^<i>ϕ</i>], where <i>Re</i>_<i>eff</i> was the Reynolds number based on <i>V</i>_<i>j,eff</i>. This new similarity parameter effectively characterized both the losses of the momentum flux and kinetic energy transport due to impinging onto a porous wall in over 50 cases from current and previous experiments, thus verifying its validity at least in the range of [(<i>Re</i>_<i>eff</i>²<i>d</i>_<i>h</i>^<i>*</i>)^<i>ϕ</i>] ≤ 1000.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 5","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143850932","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":"Simultaneous measurements of velocity, oxygen concentration, and deformed interface position in an air–water channel using PIV and LIF","authors":"Adharsh Shankaran,&nbsp;R. Jason Hearst","doi":"10.1007/s00348-025-04017-w","DOIUrl":"10.1007/s00348-025-04017-w","url":null,"abstract":"<div><p>Oxygen transfer across a deforming air–water interface is studied using a synergy of particle image velocimetry and laser-induced fluorescence (LIF). Such approaches have previously been limited to flat interfaces. We develop simultaneous measurements of velocity fields, dissolved oxygen (DO) concentration fields, and interface positions for spatial and temporal tracking. The imaging process begins after the DO in the water has been chemically depleted and continues until the water is saturated with DO. The oxygen LIF intensity field is calibrated using measurements from an optical oxygen probe to ensure accurate conversion into physical unit (mg/L). A canonical air turbulent channel flow, with a centerline velocity of 6.6 m/s (Reynolds number based on channel height of 21,700), develops for more than 100 heights before the bottom boundary condition is changed from a solid wall to a water surface. This induces transient and wavy structures on the air–water interface and generates velocity fluctuations and vorticity on the water side, which drives DO transport. The spatial evolution of DO concentration reveals steep gradients near the interface that diminish with depth, while the temporal evolution shows a reduction in concentration differences between the bulk and interface from about 35% to less than 5% as the water saturates. Concentration fluctuations are lower near the interface compared to the bulk and diminish in time as the system approaches saturation. Turbulent scalar transport analysis shows high vertical flux near the interface, and this too changes as the bulk DO concentration evolves, emphasizing that the observed phenomena are transient and should be treated as such.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 5","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-025-04017-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848987","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":"Data assimilation: new impetus in experimental fluid dynamics","authors":"Chuangxin He,&nbsp;Sen Li,&nbsp;Yingzheng Liu","doi":"10.1007/s00348-025-04020-1","DOIUrl":"10.1007/s00348-025-04020-1","url":null,"abstract":"<div><p>Data assimilation (DA), the science of fusing different observation sources to predict possible statistics of a dynamical system, originated from the field of numerical weather prediction and later was applied for applications in geoscience, geomechanics, and engineering. In the past decade, DA has received extensive attention in experimental fluid dynamics, with typical applications spanning from data analysis and error reduction to measurement data augmentation. The predictive (physical) model used in DA is critically important, differing from the data-driven approaches in machine learning. This review provides a basic understanding of the DA methodology, the mathematics involved at the grassroots level, and the various applications in the fluid measurement community.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"66 5","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143835551","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}