Experiments in Fluids最新文献_第5页

Characterization of a hypersonic turbulent boundary layer along a sharp cone with smooth and transverse square−bar roughened wall 带有光滑和横向方棒粗化壁的尖锥沿线高超音速湍流边界层的特征描述

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-09-18 DOI: 10.1007/s00348-024-03876-z

Dominik Neeb, Pascal Marquardt, Ali Gülhan

{"title":"Characterization of a hypersonic turbulent boundary layer along a sharp cone with smooth and transverse square−bar roughened wall","authors":"Dominik Neeb, Pascal Marquardt, Ali Gülhan","doi":"10.1007/s00348-024-03876-z","DOIUrl":"10.1007/s00348-024-03876-z","url":null,"abstract":"<div><p>In the present study, the response of a hypersonic turbulent boundary layer at an inflow of <i>Ma</i><sub>∞</sub> = 6 and <i>Re</i><sub>∞</sub> = 16·10<sup>6</sup> 1/m to a smooth and rough surface along a sharp cone is examined. The model consisted of three segments with exchangeable parts to consider smooth and rough surfaces with a roughness topology of square bar elements with a nominal wavelength of four times the height of the elements. In selected regions of interest, the flow field was measured by particle image velocimetry (PIV) which enabled analysis of mean velocity fields and Reynolds stresses. Van Driest transformed smooth wall mean velocity profiles showed the expected incompressible behavior and compared well to previous investigations. A combination of an integral and fitting approach is discussed to enable inner scaling of the rough wall profiles, which showed the expected shift below the smooth wall profile. The smooth wall turbulence profiles from PIV agreed to artificially filtered DNS in case of the streamwise component. Turbulence profiles above the smooth and rough wall agreed to within measurement accuracies. Additionally, two−point correlations were used to investigate turbulent structures above the smooth and rough wall. Both, length scales and orientations of the correlations, showed high level of agreement between smooth and rough walls, with only differences close to the wall. Furthermore, uniform momentum zones could be identified with similar behavior along both smooth and rough walls. Information from turbulence data support outer layer similarity, whereas mean velocity profiles show an increase in Coles wake parameter for the rough wall data. This might be influenced by transitional roughness effects.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-024-03876-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253546","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}

引用次数: 0

Correction to: Particle image velocimetry in refractive index felds of combustion flows 更正：燃烧流折射率场中的粒子图像测速仪

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-09-16 DOI: 10.1007/s00348-024-03861-6

Christoph Vanselow, Dirk Stöbener, Johannes Kiefer, Andreas Fischer

引用次数: 0

A meshless and binless approach to compute statistics in 3D ensemble PTV 计算三维集合 PTV 统计数据的无网格和无二进制方法

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-09-14 DOI: 10.1007/s00348-024-03878-x

Manuel Ratz, Miguel A. Mendez

{"title":"A meshless and binless approach to compute statistics in 3D ensemble PTV","authors":"Manuel Ratz, Miguel A. Mendez","doi":"10.1007/s00348-024-03878-x","DOIUrl":"10.1007/s00348-024-03878-x","url":null,"abstract":"<div><p>We propose a method to obtain super-resolution of turbulent statistics for three-dimensional ensemble particle tracking velocimetry (EPTV). The method is “meshless” because it does not require the definition of a grid for computing derivatives, and it is “binless” because it does not require the definition of bins to compute local statistics. The method combines the constrained radial basis function (RBF) formalism introduced Sperotto et al. (Meas Sci Technol 33:094005, 2022) with an ensemble trick for the RBF regression of flow statistics. The computational cost for the RBF regression is alleviated using the partition of unity method (PUM). Three test cases are considered: (1) a 1D illustrative problem on a Gaussian process, (2) a 3D synthetic test case reproducing a 3D jet-like flow, and (3) an experimental dataset collected for an underwater jet flow at <span>(text {Re} = 6750)</span> using a four-camera 3D PTV system. For each test case, the method performances are compared to traditional binning approaches such as Gaussian weighting (Agüí and Jiménez in JFM 185:447–468, 1987), local polynomial fitting (Agüera et al. in Meas Sci Technol 27:124011, 2016), as well as binned versions of RBFs.\u0000</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253492","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}

引用次数: 0

KF-PEV: a causal Kalman filter-based particle event velocimetry KF-PEV：基于因果卡尔曼滤波器的粒子事件测速仪

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-09-11 DOI: 10.1007/s00348-024-03877-y

Osama AlSattam, Michael Mongin, Mitchell Grose, Sidaard Gunasekaran, Keigo Hirakawa

{"title":"KF-PEV: a causal Kalman filter-based particle event velocimetry","authors":"Osama AlSattam, Michael Mongin, Mitchell Grose, Sidaard Gunasekaran, Keigo Hirakawa","doi":"10.1007/s00348-024-03877-y","DOIUrl":"10.1007/s00348-024-03877-y","url":null,"abstract":"<div><p>Event-based pixel sensors asynchronously report changes in log-intensity in microsecond-order resolution. Its exceptional speed, cost effectiveness, and sparse event stream make it an attractive imaging modality for particle tracking velocimetry. In this work, we propose a causal Kalman filter-based particle event velocimetry (KF-PEV). Using the Kalman filter model to track the events generated by the particles seeded in the flow medium, KF-PEV yields the linear least squares estimate of the particle track velocities corresponding to the flow vector field. KF-PEV processes events in a computationally efficient and streaming manner (i.e., causal and iteratively updating). Our simulation-based benchmarking study with synthetic particle event data confirms that the proposed KF-PEV outperforms the conventional frame-based particle image/tracking velocimetry as well as the state-of-the-art event-based particle velocimetry methods. In a real-world water tunnel event-based sensor data experiment performed on what we believe to be the widest field view ever reported, KF-PEV accurately predicted the expected flow field of the SD7003 wing, including details such as the lower velocity in the wake and the flow separation around the underside of an angled wing.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-024-03877-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218606","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}

引用次数: 0

Multiphase distribution in partly saturated hierarchical nonwoven fibre networks under applied load using X-ray computed tomography 利用 X 射线计算机断层扫描分析外加载荷作用下部分饱和分层无纺纤维网中的多相分布

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-09-09 DOI: 10.1007/s00348-024-03869-y

Patrick Wegele, Tomas Rosén, Daniel Söderberg

{"title":"Multiphase distribution in partly saturated hierarchical nonwoven fibre networks under applied load using X-ray computed tomography","authors":"Patrick Wegele, Tomas Rosén, Daniel Söderberg","doi":"10.1007/s00348-024-03869-y","DOIUrl":"10.1007/s00348-024-03869-y","url":null,"abstract":"<div><p>In many industrial applications, nonwoven fibre networks are facilitated to operate under partly saturated conditions, allowing for filtration, liquid absorption and liquid transport. Resolving the governing liquid distribution in loaded polyamide-6 (PA6) fibre networks using X-ray computed micro-tomography is a challenge due to the similar X-ray attenuation coefficients of water and PA6 and limitations in using background subtraction techniques if the network is deformed, which will be the case if subjected to compression. In this work, we developed a method using a potassium iodide solution in water to enhance the liquid’s attenuation coefficient without modifying the water’s rheological properties. Therefore, we studied the evolving liquid distribution in loaded and partly saturated PA6 fibre networks on the microscale. Increasing the external load applied to the network, we observed an exponential decrease in air content while the liquid content was constant, increasing the overall saturation with increasing network strain. Furthermore, the microstructural properties created by the punch-needle process in the manufacturing of the network significantly influenced the out-of-plane liquid distribution. The method has been proven helpful in understanding the results of adaptions in both the fibre network design and manufacturing process, allowing for investigating the resulting liquid distribution on a microscale.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-024-03869-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218608","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}

引用次数: 0

DMD-based spatiotemporal superresolution measurement of a supersonic jet using dual planar PIV and acoustic data 利用双平面 PIV 和声学数据对基于 DMD 的超音速射流进行时空超分辨率测量

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-09-09 DOI: 10.1007/s00348-024-03872-3

Sayumi Kaneko, Alvaro del Pozo, Hiroki Nishikori, Yuta Ozawa, Taku Nonomura

引用次数: 0

Laser stripe measurement of near-wall solids distribution in channel flow with intense transport of bimodal sediment 用激光条纹测量双峰沉积物密集输送的河道水流中的近壁固体分布

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-09-08 DOI: 10.1007/s00348-024-03874-1

Jan Krupička, Tomáš Picek, Václav Matoušek

{"title":"Laser stripe measurement of near-wall solids distribution in channel flow with intense transport of bimodal sediment","authors":"Jan Krupička, Tomáš Picek, Václav Matoušek","doi":"10.1007/s00348-024-03874-1","DOIUrl":"10.1007/s00348-024-03874-1","url":null,"abstract":"<div><p>The laser stripe method (LSM) for measuring solids distribution in sediment-laden flow has been extended to accommodate the presence of multiple sediment fractions which can differ in particle size and shape. A measurement setup with two lasers emitting green and red laser sheets was utilized to measure the vertical distribution of the near-wall concentration of a bimodal sediment mixture composed of green and red particles. The extended method was calibrated under controlled conditions in a calibration cell and was validated for measuring distributions in sediment-laden flow in a laboratory tilting flume. The results from the flume demonstrate that the extended LSM can successfully produce vertical profiles of the total concentration of all particles and the relative concentration of the two fractions. The accuracy of total concentration measurements using the extended LSM is consistent with that of the original LSM, both exhibiting an error of 0.015. The extended LSM evaluates the relative proportion of individual fractions with an error of 0.05.</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":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218609","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}

引用次数: 0

Profilometry: a non-intrusive active stereo-vision technique for wave-profile measurements in large hydrodynamic laboratories 轮廓测量：用于大型流体力学实验室波浪轮廓测量的非侵入式主动立体视觉技术

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-09-06 DOI: 10.1007/s00348-024-03879-w

Luca Savio, Alireza Ahani, Marilena Greco, Bjørn Christian Abrahamsen

{"title":"Profilometry: a non-intrusive active stereo-vision technique for wave-profile measurements in large hydrodynamic laboratories","authors":"Luca Savio, Alireza Ahani, Marilena Greco, Bjørn Christian Abrahamsen","doi":"10.1007/s00348-024-03879-w","DOIUrl":"10.1007/s00348-024-03879-w","url":null,"abstract":"<div><p>Profilometry is proposed as a novel non-intrusive image-based technique to capture the profile of the air–water interface as a dense point cloud. It can be classified as an active stereo-vision method applied to the study of gravity-driven water waves and specifically developed to be used in large hydrodynamic laboratories. As an active vision technique, it relies on the use of light sources, and as a stereo technique, it requires one or more high-speed camera pairs for imaging the same scene synchronously. To enhance the visibility of the laser lights on the wave profile, the water surface is sprayed with water droplets. Profilometry, compared to standard wave probes, can be considered as an alternative source of information that can augment spatial resolution to the identification of the air–water interface to capture nonlinear wave-evolution mechanisms and violent wave–body interactions. Its feasibility and accuracy are examined preliminarily in a small-scale flume and then in a large-scale towing tank using long-crested wave scenarios, including regular, irregular, and focused gravity-driven waves, without the presence of a structure. The values of the wave steepness examined were various and included also quite steep cases with nearly vertical wave fronts. Role played by parameters of the technique, as well as of its setup in capturing the wave features are also analysed, with the aim to provide a useful guidance for other researchers that intent to use and develop further this approach.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-024-03879-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218611","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}

引用次数: 0

Characterizing visual structures in a buoyant plume 浮力羽流中视觉结构的特征

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-08-31 DOI: 10.1007/s00348-024-03862-5

Biman Kalita, Luisa P. Florez, Ella Landau, Riley Ward, James Holyoke, Blair A. Johnson

{"title":"Characterizing visual structures in a buoyant plume","authors":"Biman Kalita, Luisa P. Florez, Ella Landau, Riley Ward, James Holyoke, Blair A. Johnson","doi":"10.1007/s00348-024-03862-5","DOIUrl":"10.1007/s00348-024-03862-5","url":null,"abstract":"<div><p>Turbulent plumes are fascinating to study in large part due to the ability to see the eddies and structures that comprise the exterior structure as they develop in space and time. We perform a laboratory study in which positively buoyant turbulent plumes are generated in a quiescent water tank. Buoyancy is varied by modifying the relative percentages of isopropyl alcohol to water in a mixture placed in a head tank. Photographs captured at steady frame rates record the evolution of the plume as it develops in time and space. A custom algorithm tracks the visible exterior outline of the plume, from which eddies and structures can be identified along the interface between the plume fluid and ambient fluid. Statistical analyses are performed to characterize differences in the distributions of external structures to study their dependence on relative buoyancy between the fluids. Spectral analysis of the edge signal of the plume reveals a <span>(-)</span>2.2 slope, indicative of the range of eddy lengths that comprise turbulent plumes. We explore the relationship between buoyancy with both the plume front velocity and plume spread angle. We find the front velocities to be functions of both the buoyancy and source Reynolds number. However, the spread angles were found to vary only with buoyancy of the plumes, thus proportional to their Richardson numbers.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218612","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}

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Pressure drop measurements over anisotropic porous substrates in channel flow 通道流中各向异性多孔基底上的压降测量

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-08-31 DOI: 10.1007/s00348-024-03873-2

Shilpa Vijay, Mitul Luhar

{"title":"Pressure drop measurements over anisotropic porous substrates in channel flow","authors":"Shilpa Vijay, Mitul Luhar","doi":"10.1007/s00348-024-03873-2","DOIUrl":"10.1007/s00348-024-03873-2","url":null,"abstract":"<p>Previous theoretical and simulation results indicate that anisotropic porous materials have the potential to reduce turbulent skin friction in wall-bounded flows. This study experimentally investigates the influence of anisotropy on the drag response of porous substrates. A family of anisotropic periodic lattices was manufactured using 3D printing. Rod spacing in different directions was varied systematically to achieve different ratios of streamwise, wall-normal, and spanwise bulk permeabilities (<span>(kappa _{xx})</span>, <span>(kappa _{yy})</span>, and <span>(kappa _{zz})</span>). The 3D printed materials were flush-mounted in a benchtop water channel. Pressure drop measurements were taken in the fully developed region of the flow to systematically characterize drag for materials with anisotropy ratios <span>(frac{kappa _{xx}}{kappa _{yy}} in [0.035,28.6])</span>. Results show that all materials lead to an increase in drag compared to the reference smooth wall case over the range of bulk Reynolds numbers tested (<span>(hbox {Re}_b in [500,4000])</span>). However, the relative increase in drag is lower for streamwise-preferential materials. We estimate that the wall-normal permeability for all tested cases exceeded the threshold identified in previous literature (<span>(sqrt{kappa _{yy}}^+> 0.4)</span>) for the emergence of energetic spanwise rollers similar to Kelvin–Helmholtz vortices, which can increase drag. The results also indicate that porous walls exhibit a departure from laminar behavior at different values for bulk Reynolds numbers depending on the geometry.</p>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-024-03873-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218610","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}

引用次数: 0