arXiv - PHYS - Fluid Dynamics最新文献_第8页

Improving agent performance in fluid environments by perceptual pretraining 通过感知预训练提高代理在流体环境中的性能

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-05 DOI: arxiv-2409.03230

Jin Zhang, Jianyang Xue, Bochao Cao

引用次数: 0

Grand-potential phase field simulations of droplet growth and sedimentation in a two-phase ternary fluid 两相三元流体中液滴生长和沉积的大势相场模拟

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-05 DOI: arxiv-2409.03401

Werner Verdier, Alain Cartalade, Mathis Plapp

引用次数: 0

A deep learning approach to wall-shear stress quantification: From numerical training to zero-shot experimental application 墙壁剪切应力量化的深度学习方法：从数值训练到零点实验应用

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-05 DOI: arxiv-2409.03933

Esther Lagemann, Julia Roeb, Steven L. Brunton, Christian Lagemann

{"title":"A deep learning approach to wall-shear stress quantification: From numerical training to zero-shot experimental application","authors":"Esther Lagemann, Julia Roeb, Steven L. Brunton, Christian Lagemann","doi":"arxiv-2409.03933","DOIUrl":"https://doi.org/arxiv-2409.03933","url":null,"abstract":"The accurate quantification of wall-shear stress dynamics is of substantial\u0000importance for various applications in fundamental and applied research,\u0000spanning areas from human health to aircraft design and optimization. Despite\u0000significant progress in experimental measurement techniques and post-processing\u0000algorithms, temporally resolved wall-shear stress dynamics with adequate\u0000spatial resolution and within a suitable spatial domain remain an elusive goal.\u0000To address this gap, we introduce a deep learning architecture that ingests\u0000wall-parallel velocity fields from the logarithmic layer of turbulent\u0000wall-bounded flows and outputs the corresponding 2D wall-shear stress fields\u0000with identical spatial resolution and domain size. From a physical perspective,\u0000our framework acts as a surrogate model encapsulating the various mechanisms\u0000through which highly energetic outer-layer flow structures influence the\u0000governing wall-shear stress dynamics. The network is trained in a supervised\u0000fashion on a unified dataset comprising direct numerical simulations of\u0000statistically 1D turbulent channel and spatially developing turbulent boundary\u0000layer flows at friction Reynolds numbers ranging from 390 to 1,500. We\u0000demonstrate a zero-shot applicability to experimental velocity fields obtained\u0000from Particle-Image Velocimetry measurements and verify the physical accuracy\u0000of the wall-shear stress estimates with synchronized wall-shear stress\u0000measurements using the Micro-Pillar Shear-Stress Sensor for Reynolds numbers up\u0000to 2,000. In summary, the presented framework lays the groundwork for\u0000extracting inaccessible experimental wall-shear stress information from readily\u0000available velocity measurements and thus, facilitates advancements in a variety\u0000of experimental applications.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Field Theory of Non-Newtonian Turbulence 非牛顿湍流场理论

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-05 DOI: arxiv-2409.03150

Esteban Calzetta

引用次数: 0

Active grid turbulence anomalies through the lens of physics informed neural networks 通过物理神经网络透视主动网格湍流异常现象

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-05 DOI: arxiv-2409.03919

Sofía Angriman, Sarah E. Smith, Patricio Clark di Leoni, Pablo J. Cobelli, Pablo D. Mininni, Martín Obligado

引用次数: 0

Development of the Multichannel Pulsed Ultrasonic Doppler Velocimeter for the measurement of liquid metal flow 开发用于测量液态金属流动的多通道脉冲超声多普勒速度计

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-04 DOI: arxiv-2409.02815

Ding-Yi Pan, Yi-Fei Huang, Ze Lyu, Juan-Cheng Yang, Ming-Jiu Ni

{"title":"Development of the Multichannel Pulsed Ultrasonic Doppler Velocimeter for the measurement of liquid metal flow","authors":"Ding-Yi Pan, Yi-Fei Huang, Ze Lyu, Juan-Cheng Yang, Ming-Jiu Ni","doi":"arxiv-2409.02815","DOIUrl":"https://doi.org/arxiv-2409.02815","url":null,"abstract":"In the present study, by adopting the advantage of ultrasonic techniques, we\u0000developed a Multichannel Pulsed Ultrasonic Doppler Velocimetry (MPUDV) to\u0000measure the 2D2C velocity fields of liquid metal flow. Due to the specially\u0000designed Ultrasonic host and post-processing scheme, the MPUDV system can reach\u0000a high spatiotemporal resolution of 50 Hz and 3 mm. The flow loop contains a\u0000cavity test section to ensure a classical recirculating flow was built to\u0000validate the accuracy of MPUDV in velocity field measurement. In the initial\u0000phase of the study, water with tracer particles was selected as the working\u0000liquid to ensure the velocity field measurements by the well-developed Particle\u0000Image Velocimetry (PIV). A comparison of the data obtained from the PIV and\u0000MPUDV methods revealed less than 3 differences in the 2D2C velocity field\u0000between the two techniques during simultaneous measurements of the same flow\u0000field. This finding strongly demonstrates the reliability of the MPUDV method\u0000developed in this paper. Moreover, the ternary alloy GaInSn was selected as the\u0000working liquid in the flow loop to validate the efficacy of the MPUDV in\u0000measuring 2D-2C velocity fields. A series of tests were conducted in the cavity\u0000at varying Reynolds numbers, ranging from 9103 to 24123. The measurements\u0000demonstrated that the MPUDV could accurately measure the flow structures\u0000characterized by a central primary circulation eddy and two secondary eddies in\u0000the opaque liquid metal. Furthermore, it was found that the vortex center of\u0000the primary circulating eddy and the size of the secondary eddies undergo\u0000significant alterations with varying Reynolds numbers, indicating the influence\u0000of inertial force on the flow characteristics in the recirculating flow. It is\u0000therefore demonstrated that the current MPUDV methodology is applicable for\u0000measuring a 2D2C velocity field in opaque liquid metal flows.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Investigation of cloud cavitating flow in a venturi using Adaptive Mesh Refinement (AMR) 利用自适应网格细化技术（AMR）研究文丘里管中的云气蚀流

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-04 DOI: arxiv-2409.02369

Dhruv Apte, Mingming Ge, Olivier Coutier-Delgosha

{"title":"Investigation of cloud cavitating flow in a venturi using Adaptive Mesh Refinement (AMR)","authors":"Dhruv Apte, Mingming Ge, Olivier Coutier-Delgosha","doi":"arxiv-2409.02369","DOIUrl":"https://doi.org/arxiv-2409.02369","url":null,"abstract":"Unsteady cloud cavitating flow is detrimental to the efficiency of hydraulic\u0000machinery like pumps and propellers due to the resulting side-effects of\u0000vibration, noise and erosion damage. Modelling such a unsteady and highly\u0000turbulent flow remains a challenging issue. In this paper, cloud cavitating\u0000flow in a venturi is calculated using the Detached Eddy Simulation (DES) model\u0000combined with the Merkle model. The Adaptive Mesh Refinement (AMR) method is\u0000employed to speed up the calculation and investigate the mechanisms for vortex\u0000development in the venturi. The results indicate the velocity gradients and the\u0000generalized fluid element strongly influence the formation of vortices\u0000throughout a cavitation cycle. In addition, the cavitation-turbulence coupling\u0000is investigated on the local scale by comparing with high-fidelity experimental\u0000data and using profile stations. While the AMR calculation is able to predict\u0000well the time-averaged velocities and turbulence-related aspects near the\u0000throat, it displays discrepancies further downstream owing to a coarser grid\u0000refinement downstream and under-performs compared to a traditional grid\u0000simulation . Additionally, the AMR calculations is unable to reproduce the\u0000cavity width as observed in the experiments. Therefore, while AMR promises to\u0000speed the process significantly by refining grid only in regions of interest,\u0000it is comparatively in line with a traditional calculation for cavitating\u0000flows. Thus, this study intends to provide a reference to employing AMR as a\u0000tool to speed up calculations and be able to simulate turbulence-cavitation\u0000interactions accurately.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"104 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Diffusion-limited settling of highly porous particles in density-stratified fluids 密度分层流体中高孔隙度颗粒的扩散受限沉降

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-04 DOI: arxiv-2409.02419

Robert Hunt, Roberto Camassa, Richard M. McLaughlin, Daniel M. Harris

{"title":"Diffusion-limited settling of highly porous particles in density-stratified fluids","authors":"Robert Hunt, Roberto Camassa, Richard M. McLaughlin, Daniel M. Harris","doi":"arxiv-2409.02419","DOIUrl":"https://doi.org/arxiv-2409.02419","url":null,"abstract":"The vertical transport of solid material in a stratified medium is\u0000fundamental to a number of environmental applications, with implications for\u0000the carbon cycle and nutrient transport in marine ecosystems. In this work, we\u0000study the diffusion-limited settling of highly porous particles in a\u0000density-stratified fluid through a combination of experiment, analysis, and\u0000numerical simulation. By delineating and appealing to the diffusion-limited\u0000regime wherein buoyancy effects due to mass adaptation dominate hydrodynamic\u0000drag, we derive a simple expression for the steady settling velocity of a\u0000sphere as a function of the density, size, and diffusivity of the solid, as\u0000well as the density gradient of the background fluid. In this regime, smaller\u0000particles settle faster, in contrast with most conventional hydrodynamic drag\u0000mechanisms. Furthermore, we outline a general mathematical framework for\u0000computing the steady settling speed of a body of arbitrary shape in this regime\u0000and compute exact results for the case of general ellipsoids. Using hydrogels\u0000as a highly porous model system, we validate the predictions with laboratory\u0000experiments in linear stratification for a wide range of parameters. Lastly, we\u0000show how the predictions can be applied to arbitrary slowly varying background\u0000density profiles and demonstrate how a measured particle position over time can\u0000be used to reconstruct the background density profile.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"182 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142226915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Kolmogorov-size particles in homogeneous and isotropic turbulence 均相和各向同性湍流中的柯尔莫哥洛夫大小粒子

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-04 DOI: arxiv-2409.02467

Alessandro Chiarini, Simone Tandurella, Marco Edoardo Rosti

{"title":"Kolmogorov-size particles in homogeneous and isotropic turbulence","authors":"Alessandro Chiarini, Simone Tandurella, Marco Edoardo Rosti","doi":"arxiv-2409.02467","DOIUrl":"https://doi.org/arxiv-2409.02467","url":null,"abstract":"We investigate the fluid-solid interaction of suspensions of Kolmogorov-size\u0000spherical particles moving in homogeneous isotropic turbulence at a microscale\u0000Reynolds number of $Re_lambda approx 140$. Two volume fractions are\u0000considered, $10^{-5}$ and $10^{-3}$, and the solid-to-fluid density ratio is\u0000set to $5$ and $100$. We present a comparison between interface-resolved\u0000(PR-DNS) and one-way-coupled point-particle (PP-DNS) direct numerical\u0000simulations. We find that the modulated energy spectrum shows the classical\u0000$-5/3$ Kolmogorov scaling in the inertial range of scales and a $-4$ scaling at\u0000smaller scales, with the latter resulting from a balance between the energy\u0000injected by the particles and the viscous dissipation, in an otherwise smooth\u0000flow. An analysis of the small-scale flow topology shows that the particles\u0000mainly favour events with axial strain and vortex compression. The dynamics of\u0000the particles and their collective motion studied for PR-DNS are used to assess\u0000the validity of the PP-DNS. We find that the PP-DNS predicts fairly well both\u0000the Lagrangian and Eulerian statistics of the particles motion for the\u0000low-density case, while some discrepancies are observed for the high-density\u0000case. Also, the PP-DNS is found to underpredict the level of clustering of the\u0000suspension compared to the PR-DNS, with a larger difference for the\u0000high-density case.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142226914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Inertial focusing of spherical capsule in pulsatile channel flows 脉动通道流中球形胶囊的惯性聚焦

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-04 DOI: arxiv-2409.02379

Naoki Takeishi, Kenta Ishimoto, Naoto Yokoyama, Marco Edoardo Rosti

{"title":"Inertial focusing of spherical capsule in pulsatile channel flows","authors":"Naoki Takeishi, Kenta Ishimoto, Naoto Yokoyama, Marco Edoardo Rosti","doi":"arxiv-2409.02379","DOIUrl":"https://doi.org/arxiv-2409.02379","url":null,"abstract":"We present numerical analysis of the lateral movement of spherical capsule in\u0000the steady and pulsatile channel flow of a Newtonian fluid, for a wide range of\u0000oscillatory frequency. Each capsule membrane satisfying strain-hardening\u0000characteristic is simulated for different Reynolds numbers Re and capillary\u0000numbers Ca. Our numerical results showed that capsules with high Ca exhibit\u0000axial focusing at finite Re similarly to the inertialess case. We observe that\u0000the speed of the axial focusing can be substantially accelerated by making the\u0000driving pressure gradient oscillating in time. We also confirm the existence of\u0000an optimal frequency which maximizes the speed of axial focusing, that remains\u0000the same found in the absence of inertia. For relatively low Ca, on the other\u0000hand, the capsule exhibits off-centre focusing, resulting in various\u0000equilibrium radial positions depending on Re. Our numerical results further\u0000clarifies the existence of a specific Re for which the effect of the flow\u0000pulsation to the equilibrium radial position is maximum. The roles of channel\u0000size and viscosity ratio on the lateral movements of the capsule are also\u0000addressed.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0