Experiments in Fluids最新文献_第8页

Robust detection and characterization of a bifurcated bi-phasic interface propagating through a granular medium: physically and morphologically 在颗粒介质中传播的分叉双相界面的稳健检测和特征描述：物理和形态学方法

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-11-26 DOI: 10.1007/s00348-024-03919-5

Rana Al Nemer, Julien Réthoré, Giulio Sciarra

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Internal wave field generated by oscillating rough topography 振荡粗糙地形产生的内波场

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-11-25 DOI: 10.1007/s00348-024-03928-4

Natasha Wilson, Julie Crockett

{"title":"Internal wave field generated by oscillating rough topography","authors":"Natasha Wilson, Julie Crockett","doi":"10.1007/s00348-024-03928-4","DOIUrl":"10.1007/s00348-024-03928-4","url":null,"abstract":"<div><p>Internal waves generated by oscillating topography with a series of ridges in a stratified medium are experimentally explored. Experiments represent oscillating tidal flow in the ocean where small-scale roughness on topography cannot be fully resolved in global circulation models, but the generated internal wave field can impact global mixing and ocean dynamics. Here, the influence of topography roughness is evaluated by including different numbers of ridges, with slopes equivalent to the edge slope of the full topography, on top of the original topography. Specifically, the internal wave field generated by a wide plateau shape is compared with the same shape except with three to six Gaussian ridges overlain on the plateau. In all scenarios, a complex pattern of internal waves generated by each ridge is observed. However, the results show as the number or width of ridges increases, the waves generated by the ridges near the center of the plateau decay very quickly and in the far field the internal wave field is indistinguishable from that generated by a smooth plateau. A non-dimensional number is suggested that accounts for both the number of ridges and overall topography width while defining a limit for which plateau-like internal wave generation is expected and this form of surface roughness may be neglected.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 12","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142694789","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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Development of simultaneous TDLAS and BOS techniques for enhanced accuracy in combustion gas temperature measurements 开发同步 TDLAS 和 BOS 技术，提高燃烧气体温度测量的精度

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-11-25 DOI: 10.1007/s00348-024-03920-y

Shinichiro Ogawa, Masayuki Kido, Yuya Hirayama

{"title":"Development of simultaneous TDLAS and BOS techniques for enhanced accuracy in combustion gas temperature measurements","authors":"Shinichiro Ogawa, Masayuki Kido, Yuya Hirayama","doi":"10.1007/s00348-024-03920-y","DOIUrl":"10.1007/s00348-024-03920-y","url":null,"abstract":"<div><p>There remain many uncertainties regarding the ignition promotion effects of the micro-rocket torch used for forced ignition in a scramjet engine. Therefore, a detailed investigation of the physical properties of the ejected gas is necessary as a preliminary step toward understanding the ignition promotion mechanisms. While tunable diode laser absorption spectroscopy (TDLAS) has been developed for high-precision optical measurements of combustion gases, it has become evident that accurately measuring the combustion gas temperature is challenging due to the presence of multiple variable fitting parameters. Therefore, in this study, TDLAS was employed to measure the gas temperature, and the accuracy was enhanced by integrating the background-oriented schlieren (BOS) technique to precisely determine the gas jet diameter. We successfully visualized the gas ejected from the torch nozzle using the BOS method. This visualization allowed us to fix the optical path length, which was previously treated as a variable fitting parameter. As a result, the TDLAS+BOS method improved the temperature measurement accuracy compared to TDLAS-only. Specifically, the simultaneous TDLAS + BOS measurements provided more accurate gas temperatures than TDLAS-only, with errors reduced to 7.5% for an equivalence ratio of 0.51 and 10.7% for an equivalence ratio of 1.38. These findings demonstrate that the integration of BOS with TDLAS significantly enhances the precision of temperature measurements in micro-rocket torch applications, contributing to a better understanding of the ignition mechanisms in supersonic flows.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 12","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142694795","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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Evolution of symmetrical microvortices in a generating microdroplet during neck breakage stage in an altered T-shaped microchannel 在改变的 T 型微通道中，产生微滴的颈部断裂阶段中对称微涡的演变

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-11-22 DOI: 10.1007/s00348-024-03923-9

Feng Shen, Xin Yang, Chunyou Li, Jia Wang, Di Wu, Zhaomiao Liu

引用次数: 0

Development of a neutralization reaction in a droplet that extracts chemically active surfactant from its homogeneous solution 在液滴中发生中和反应，从均质溶液中提取化学活性表面活性剂

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-11-19 DOI: 10.1007/s00348-024-03899-6

M. O. Denisova, К. G. Kostarev

{"title":"Development of a neutralization reaction in a droplet that extracts chemically active surfactant from its homogeneous solution","authors":"M. O. Denisova, К. G. Kostarev","doi":"10.1007/s00348-024-03899-6","DOIUrl":"10.1007/s00348-024-03899-6","url":null,"abstract":"<div><p>The evolution of the neutralization reaction in a stationary droplet of cylindrical shape, extracting a surfactant from the surrounding mixture in a vertical Hele-Shaw cell, was studied experimentally. In our experiment, we used a new method of the simultaneous visualization of the refractive index field of light and the distribution of acidity levels in the solutions of source reactants and reaction products within the droplet. To carry out this approach, we utilized a Fizeau interferometer and added a pH indicator to the droplet before the experiment. A digital video camera recorded the resulting interference pattern with the superimposed color distribution created by solutions with different acidity levels. The study was conducted on a system of liquids where the chemical potentials would be equal when the concentration of the extracted reactant in the droplet was much higher than in the surrounding environment. Two variants of reaction realization—with and without Marangoni convection development—were considered. We determined the structures of flows and concentration fields in the droplet and its neighborhood and traced their evolution. Also, we evaluated the characteristic times of the extraction process depending on the initial reactant concentrations and droplet sizes. It was found that the resulting Marangoni convection had an oscillatory character and continued after the reaction completion. As expected, the formation of the capillary motion intensified the progression of chemical reaction inside the droplet.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 12","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142672437","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

Wall pressure control of a 3D cavity with lateral apertures and wall proximity 具有横向开孔和接近壁面的三维空腔的壁面压力控制

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-11-15 DOI: 10.1007/s00348-024-03900-2

Tarek Ammam, Laurent Keirsbulck, Jérémy Basley, Etienne Grappein, Sebastien Delprat, Tewfik Benazzouz, Denis Cornu, Marc Lippert, David Boussemart

{"title":"Wall pressure control of a 3D cavity with lateral apertures and wall proximity","authors":"Tarek Ammam, Laurent Keirsbulck, Jérémy Basley, Etienne Grappein, Sebastien Delprat, Tewfik Benazzouz, Denis Cornu, Marc Lippert, David Boussemart","doi":"10.1007/s00348-024-03900-2","DOIUrl":"10.1007/s00348-024-03900-2","url":null,"abstract":"<div><p>Flows over cavities are relevant to many branches of engineering and are known to be a source of instabilities, high-pressure disturbances, and large recirculating regions, leading to excessive pressure loads. In this paper, we study the dynamical behavior of a 6.44:1 length-to-depth transitional cavity flow (i.e., where the shear layer partly enters the cavity) with wall proximity and lateral apertures. Mitigation of pressure loads is investigated through steady blowing upstream of the cavity’s leading edge. Concurrent pressure and particle image velocimetry (PIV) measurements along with companion unsteady numerical simulations have been performed to identify the mechanisms underlying the flow dynamics of both baseline and controlled cases. Experiments are reproduced numerically using the Improved Delayed Detached Eddy Simulations (<span>IDDES</span>) approach with shear stress transport eddy viscosity model (<span>(k-omega)</span> SST) at a Reynolds number of <span>(Re=2.8 times 10^5)</span>. Results underline that steady blowing changes the flow drastically upstream of the cavity by thickening the boundary layer and reducing the flow rate passing the cavity. The controlled flow transforms the dynamics of the cavity shear layer, impacting the inner cavity flow, and leads to a significant reduction of the pressure loads. This mitigation is associated with a strong reduction in turbulent momentum at the shear layers interface.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 12","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142636772","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

Multiscale analysis of the textural atomization process of a rocket engine-assisted coaxial jet 火箭发动机辅助同轴射流纹理雾化过程的多尺度分析

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-11-14 DOI: 10.1007/s00348-024-03916-8

Leonardo Geiger, Nicolas Fdida, Christophe Dumouchel, Jean-Bernard Blaisot, Luc-Henry Dorey, Marie Théron

{"title":"Multiscale analysis of the textural atomization process of a rocket engine-assisted coaxial jet","authors":"Leonardo Geiger, Nicolas Fdida, Christophe Dumouchel, Jean-Bernard Blaisot, Luc-Henry Dorey, Marie Théron","doi":"10.1007/s00348-024-03916-8","DOIUrl":"10.1007/s00348-024-03916-8","url":null,"abstract":"<div><p>A method for analyzing liquid ligaments of a textural atomization process is presented in this article for the case of a rocket engine type-assisted atomization process under combustion. The operating point positions the atomization process in the fiber-type regime carrying an intense textural atomization process. Multiscale in nature, the method based on image analysis associates a scale distribution with a family of ligaments, this distribution being sensitive to the number, size and shape of these ligaments. The quality of scale distributions measured by image analysis depends on the spatial resolution and the precision of area measurements of surfaces with curved boundaries but described by square pixels. Part of the work consisted of improving the method for measuring scale distributions by using a sub-pixel image analysis technique and refining the surface area measurement method. Another part directed the multiscale analysis toward the estimation of the diameter distributions of the blobs that characterize the large-scale deformation of the ligaments<b>.</b> The analysis describes the atomization process at a level of detail never reached. For instance, assuming that the blobs are drops in formation, the estimated diameter distribution (bimodal in the case examined here) and the number of these drops are evaluated as a function of the distance from the injector. This information indicates where the process is most intense and where it stops. Furthermore, these diameter distributions receive a mathematical expression whose parameters report clear evolutions with the distance from the injector. This shows the possibility of elaborating mathematical models appropriate for textural atomization mechanisms.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 12","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142636725","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

Conditional statistics at the turbulent/non-turbulent interface of variable viscosity jets 可变粘度喷流湍流/非湍流界面的条件统计数据

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-11-13 DOI: 10.1007/s00348-024-03915-9

Léa Voivenel, Emilien Varea, Gilles Godard, Luminita Danaila

{"title":"Conditional statistics at the turbulent/non-turbulent interface of variable viscosity jets","authors":"Léa Voivenel, Emilien Varea, Gilles Godard, Luminita Danaila","doi":"10.1007/s00348-024-03915-9","DOIUrl":"10.1007/s00348-024-03915-9","url":null,"abstract":"<div><p>In nature as well as in industrial applications, turbulent mixing is ubiquitous. In most cases, these are different fluids with different physical properties (density and/or viscosity). Moreover, all important changes such as mass, momentum and scalar fluxes occur across the turbulent/non-turbulent interface, a thin and sharp layer that separates the turbulent core from the irrotational surrounding fluid. In this paper, we present statistics conditioned on the instantaneous interface position in the very near field of a variable viscosity jet to study the birth and growth of turbulence. The simultaneous scalar concentration and velocity fields are obtained from planar laser-induced fluorescence, where the images undergo an original correction and normalization process, and stereo-particle image velocimetry, respectively. We show that the turbulence is much more advanced in the variable viscosity flow (VVF), which exhibits some features that are visible much later in the constant viscosity flow (CVF). Furthermore, this study reveals a change in the nature of the mixing process between VVF and CVF, which needs to be further investigated.</p></div>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 12","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142636894","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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Viscous and turbulent stress measurements above and below laboratory wind waves 实验室风浪上方和下方的粘应力和湍流应力测量结果

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-11-13 DOI: 10.1007/s00348-024-03898-7

Janina Tenhaus, Marc P. Buckley, Silvia Matt, Ivan B. Savelyev

{"title":"Viscous and turbulent stress measurements above and below laboratory wind waves","authors":"Janina Tenhaus, Marc P. Buckley, Silvia Matt, Ivan B. Savelyev","doi":"10.1007/s00348-024-03898-7","DOIUrl":"10.1007/s00348-024-03898-7","url":null,"abstract":"<p>The influence of wind stress, wind drift, and wind-wave (microscale) breaking on the coupled air–sea boundary layer is poorly understood. We performed high-resolution planar and stereo velocity measurements within the first micrometers to centimeters above and below surface gravity waves at the University of Miami’s SUSTAIN air–sea interaction facility. A particle image velocimetry (PIV) system was adapted and installed in the large (18 m long, 6 m wide) wind-wave tunnel at a fetch of approximately 10 m. In addition, wave field properties were captured by laser-induced fluorescence (LIF). Experiments were conducted with wind waves and wind over mechanically generated swell. In this work, we focus on rather smooth, young, wind-generated waves. We present instantaneous velocity and vorticity fields above and below the air–water interface for the same wind-wave conditions. Both instantaneous and phase-averaged fields show strong along-wave modulations in viscous stress. For steeper waves, we observe airflow separation and increased negative turbulent stress below crests, accompanied by sporadic drops in viscous stress below zero. We describe the wave-induced modulations of the airflow structure as well as the wind-induced water dynamics and discuss the importance of the viscous stress for the total momentum budget.</p>","PeriodicalId":554,"journal":{"name":"Experiments in Fluids","volume":"65 12","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00348-024-03898-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142636895","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

Flow sensors for on-chip microfluidics: promise and challenges 用于片上微流体的流量传感器：前景与挑战

IF 2.3 3区工程技术

Experiments in Fluids Pub Date : 2024-11-12 DOI: 10.1007/s00348-024-03918-6

Harsh Deswal, Shivji Prasad Yadav, Shiv G. Singh, Amit Agrawal

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