Experiments in Fluids最新文献

{"title":"Identifying dominant flow features from very-sparse Lagrangian data: a multiscale recurrence network-based approach","authors":"Giovanni Iacobello,&nbsp;David E. Rival","doi":"10.1007/s00348-023-03700-0","DOIUrl":"10.1007/s00348-023-03700-0","url":null,"abstract":"<p>Realistic fluid flow problems often require that Lagrangian tracers are deployed in a sparse or very-sparse manner, such as for oceanic and atmospheric flows where large-scale motion needs characterisation. Data sparsity represents a significant issue in Lagrangian analysis, especially for data-driven methods that rely heavily on large datasets. We propose a multiscale spatial recurrence network (MSRN) methodology for characterising very-sparse Lagrangian data, which exploits individual tracks and a spatial recurrence criterion to identify the spatio-temporal complexity of tracer trajectories. The MSRN is an unsupervised modelling framework that does not require <i>a priori</i> parameter setting, and—through the quantification of persistent link activation at specific trajectory intervals—can reveal the presence of dominant looping scales in a variety of salient fluid flows. This new paradigm is shown to be successful for the study of Lagrangian tracers seeded in complex (realistic) flows, including unsteady and advection-dominated problems. This makes MSRNs an effective and versatile tool to characterise sensor trajectories in key problems such as environmental processes critical to understanding and mitigating climate change.</p>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"64 10","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-023-03700-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41080068","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":"Spatiotemporal boundary dissipation measurement in Taylor–Couette flow using diffusing-wave spectroscopy","authors":"Enzo Francisco,&nbsp;Vincent Bouillaut,&nbsp;Tong Wu,&nbsp;Sébastien Aumaître","doi":"10.1007/s00348-023-03693-w","DOIUrl":"10.1007/s00348-023-03693-w","url":null,"abstract":"<div><p>Diffusing-wave spectroscopy (DWS) allows for the direct measurement of the squared strain-rate tensor. When combined with commonly available high-speed cameras, we show that DWS gives direct access to the spatiotemporal variations of the viscous dissipation rate of a Newtonian fluid flow. The method is demonstrated using a Taylor–Couette (TC) cell filled with a lipid emulsion or a TiO₂ suspension. We image the boundary dissipation rate in a quantitative and time-resolved fashion by shining coherent light at the experimental cell and measuring the local correlation time of the speckle pattern. The results are validated by comparison with the theoretical prediction for an ideal TC flow and with global measurements using a photomultiplier tube and a photon correlator. We illustrate the method by characterizing the spatial organization of the boundary dissipation rate past the Taylor–Couette instability threshold, and its spatiotemporal dynamics in the wavy vortex flow that arises beyond a secondary instability threshold. This study paves the way for direct imaging of the dissipation rate in a large variety of flows, including turbulent ones.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"64 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47319706","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":"Correction to: Volumetric study of a turbulent boundary layer and swept impinging oblique SBLI at Mach 2.3","authors":"James A. S. Threadgill,&nbsp;Jesse C. Little","doi":"10.1007/s00348-023-03689-6","DOIUrl":"10.1007/s00348-023-03689-6","url":null,"abstract":"","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"64 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44349984","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":"Single-camera PTV within interfacially sheared drops in microgravity","authors":"Patrick M. McMackin,&nbsp;Joe A. Adam,&nbsp;Frank P. Riley,&nbsp;Amir H. Hirsa","doi":"10.1007/s00348-023-03697-6","DOIUrl":"10.1007/s00348-023-03697-6","url":null,"abstract":"<div><p>Development of experimental methods for in situ particle tracking velocimetry (PTV) is fundamental for allowing measurement of moving systems non-tailored for velocimetry. This investigation focuses on the development of a post-processing methodology for single-camera PTV, without laser-sheet illumination, tracking native air bubbles as tracer particles within a liquid drop of human insulin in microgravity. Human insulin functioned as a sufficiently complex, non-Newtonian fluid system for testing fluid measurement methodology. The PTV scenario was facilitated by microgravity technology known as the ring-sheared drop (RSD), aboard the International Space Station, which produced an optical imaging scenario and fluid flow geometry suitable as a testbed for PTV research. The post-processing methodology performed included five steps: (i) physical system characterization and native air bubble tracer identification, (ii) image projection and single-camera calibration, (iii) depth determination and 3D particle position determination, (iv) ray tracing and refraction correction, and (v) particle history and data expansion for suboptimal particles. Overall, this post-processing methodology successfully allowed for a total of 1085 particle measurements in a scenario where none were previously possible. Such post-processing methodologies have promise for application to other in situ PTV scenarios allowing better understanding of physical systems whose flow is difficult to measure and/or where PTV-specific optical elements (such as laser light sheets and dual-camera setups) are not permissible due to physical or safety constraints.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"64 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42196290","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 dynamics and heat transfer characterization of confined multiple jets impinging on a complex surface","authors":"F. V. Barbosa,&nbsp;S. F. C. F. Teixeira,&nbsp;J. C. F. Teixeira","doi":"10.1007/s00348-023-03692-x","DOIUrl":"10.1007/s00348-023-03692-x","url":null,"abstract":"<div><p>Submerged and confined multiple jet impingement is widely implemented in cooling applications since it provides high heat transfer coefficients and uniformity over the target plate. Its performance depends on several variables that make it complex and difficult to control. To understand the physical phenomena and characterize the flow field, an in-depth study, using Particle Image Velocimetry (PIV) technique and an heat flux sensor, is conducted in this study. The PIV provides relevant data, but the accuracy of the measurements depends on an effective experimental setup and a careful selection of the most appropriate tracer particles. Therefore, this work presents the purpose-built experimental apparatus and comprises an analysis of the efficiency of different seeding particles. The results demonstrate that olive oil particles are appropriate to track turbulent flows since particles with about 1 μm diameter are obtained by the seeding generator. PIV measurements highlight the complexity of the jet flow impinging on a step surface, which induces a strong flow reversal that affects the jet flow development and the interaction with the adjacent jets. The large-scale structures induced in the vicinity of the target plate are captured by the PIV, as well as the strong fountain flows generated between the adjacent jets. Compared with the flat geometry, the turbulence intensity at the central jet is around 25% higher for the 1 <i>D</i> step, while for the 2 <i>D</i> step, this increase reaches 7.5%. The increased turbulence intensity leads to an heat transfer enhancement. For the 2 <i>D</i> step plate, the Nusselt number recorded is 25% greater than the flat plate. Through this study, relevant insights for several engineering applications that use multiple jet impingement are provided, highlighting that the combination of PIV and heat flux sensors are appropriate to characterize the jet’s flow dynamics and the heat transfer of this complex process.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"64 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-023-03692-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48369140","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":"Digital holographic microscopy for measurement of instantaneous contact angle of an evaporating droplet","authors":"Mohammad Mehdi Zamani Asl,&nbsp;Carlos A. Dorao,&nbsp;Alberto Giacomello,&nbsp;Maria Fernandino","doi":"10.1007/s00348-023-03696-7","DOIUrl":"10.1007/s00348-023-03696-7","url":null,"abstract":"<div><p>Despite the apparent simplicity of the process of a droplet evaporating on a substrate, the temporal evolution of the local contact angle along the droplet periphery during the evaporation is still not fully understood. In this work, digital holographic microscopy is used for capturing the time evolution of the droplet surface at submicron resolution. The three-dimensional surface provides the information for determining the instantaneous three-phase contact line and the local apparent contact angle along the whole droplet periphery. The apparent contact angle is computed from the gradient of the droplet surface and defined as the maximum slope of this function along the periphery of the droplet. The method is then applied to study the diffusion dominated evaporation of nanoliter droplets on a hydrophilic substrate. For the case of a non-axisymmetric droplet, differences of up to 10<span>(^circ)</span> in contact angle along the contact line were identified when the contact line went from one pinning position to another. Digital holographic microscopy allowed us to characterize the irregular motion of the contact line and local changes in contact angle during the evaporation process.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"64 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-023-03696-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48517284","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":"Double-pass imaging background-oriented schlieren technique for focusing on measurement target","authors":"Y. Hirose,&nbsp;M. Yamagishi,&nbsp;S. Udagawa,&nbsp;T. Inage,&nbsp;Y. Tagawa,&nbsp;M. Ota","doi":"10.1007/s00348-023-03694-9","DOIUrl":"10.1007/s00348-023-03694-9","url":null,"abstract":"<div><p>This paper introduces the double-pass imaging background-oriented schlieren (DPBOS) technique to overcome a defocusing problem of conventional background-oriented schlieren (BOS) systems. In the conventional BOS system, a camera focuses on a background situated behind a measurement target, which inevitably causes a blurred image of the target. The advantage of the proposed technique, using a digital projector with proper optical alignment, is that the camera focuses on both the target and the background image at the same time. Therefore, measurement in the vicinity of the target can be achieved with higher sensitivity than that of the conventional BOS system. For validation, a test target (lens) and the density field near a heat sink are measured using the DPBOS. The results show good agreement with theoretical prediction and exhibit higher sensitivity than the conventional and telecentric BOS system. In addition, the accuracy of DPBOS was assessed by comparing the calculated surface temperatures from the displacement of DPBOS and conventional BOS with the corresponding theoretical temperature. As the results, the DPBOS and conventional BOS have errors of 3% and 9%, respectively. The proposed method clearly shows the advantage of DPBOS over BOS in overcoming the defocus problem and achieving high-accuracy measurements.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"64 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45655989","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":"Experimental study on internal flow structure and dynamics of dense liquid-particle flow down inclined channel","authors":"Yunhui Sun,&nbsp;Jiajun Jiao,&nbsp;Yi An,&nbsp;Xiaoliang Wang,&nbsp;Qingquan Liu","doi":"10.1007/s00348-023-03691-y","DOIUrl":"10.1007/s00348-023-03691-y","url":null,"abstract":"<div><p>Dense granular flows widely exist in the environment and industry where inter-particle interactions play essential role. Studying the flow behaviour is important for a better understanding and more scientific description of the granular rheology. This paper experimentally investigates liquid-particle mixture dense flows down an inclined channel with bumpy-frictional base. The refractive index matching method is used which permits the determination of the internal flow information, including the velocity, shear rate, granular temperature and solid concentration. It is observed that the wall influence is minor at the observing position. The pressure and shear stress obtained from the integration of the solid concentration matches well with the prediction of the kinetic theory. The particle interaction pattern is analysed from the rheology properties and a coherence length approach. The flow is found to be rheologically stratified, with the near-bottom being collision-dominated and the near-surface being friction-dominated. The bottom pore pressure and stress are also directly measured and analysed in combination with the internal kinetic properties.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"64 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4779922","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":"Large-scale volumetric particle tracking using a single camera: analysis of the scalability and accuracy of glare-point particle tracking","authors":"F. Kaiser,&nbsp;D. E. Rival","doi":"10.1007/s00348-023-03682-z","DOIUrl":"10.1007/s00348-023-03682-z","url":null,"abstract":"<div><p>Recent advances in tracer, illumination, and camera technology, paired with new processing algorithms, have been pushing the limits of scale for three-dimensional flow measurements. The present study explores the state of the art and discusses the current progress toward full-scale, in situ flow measurements in very large measurement volumes of order <span>(10,mathrm {m^2})</span> or larger. In particular, we focus on industrial and environmental applications, where the measurement time, the processing time, and overall system cost all have to be minimized. With the glare-point particle tracking (GPPT) approach, we present a cost and time-efficient volumetric measurement technique using a single-camera setup, air-filled soap bubbles (AFSBs), and natural illumination. The GPPT approach was tested and characterized in a pyramidal-shaped measurement volume (<span>(V=18;textrm{m}^3)</span>) in an outdoor, open-jet wind tunnel. Bubbles of uniform size were produced by a bubble-generator prototype and illuminated by the sun. The uniform bubble size enabled a depth estimate for each bubble based on the glare-point spacing in the images from a single camera, thereby removing the need for additional cameras and perspectives. The measurement accuracy of the GPPT is then assessed by: (a) characterizing the performance of the bubble-generator prototype; (b) analyzing bubble deformation and its effects; and (c) assessing the accuracy of the depth estimate based on glare-point spacing. Finally, the scalability of the approach is discussed and, based on the light-scattering behavior of large AFSBs, a discussion is made of how GPPT will enable three-dimensional flow characterization in very large measurement volumes (<span>(V=mathcal {O}(100,textrm{m}^3))</span>) in the near future.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"64 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4742553","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":"LIF-based quantification of the species transport during droplet impact onto thin liquid films","authors":"Hatim Ennayar,&nbsp;Philipp Brockmann,&nbsp;Jeanette Hussong","doi":"10.1007/s00348-023-03688-7","DOIUrl":"10.1007/s00348-023-03688-7","url":null,"abstract":"<p>In the present study, laser-induced fluorescence (LIF) is used to investigate the mixing process of a droplet impacting onto a thin liquid film. A robust multidimensional calibration procedure is developed enabling the extraction of local instantaneous dye concentrations as well as film heights. A series of validation measurements are conducted confirming a low reconstruction error of <span>(4.53%)</span>. The impact-induced mixing process is thoroughly investigated across various liquid film thicknesses to examine the propagation of the mixing zone and the instantaneous radial concentration gradients within it. It is shown that the maximum extent of the mixing zone scales inversely proportional with the thickness of the liquid film. Within our experiments, we discover the formation of wall-induced vortex ring instabilities subsequent to impact. The disintegration of vortex rings during droplet impact significantly enhances convection-driven mixing, as quantified by the coefficient of variation.</p>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"64 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-023-03688-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4671274","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}