arXiv - PHYS - Fluid Dynamics最新文献_第3页

A novel volume of fluid ghost-cell immersed boundary method for free surface flow interacting with structures 针对与结构相互作用的自由表面流的新型流体幽灵单元沉浸边界法

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-13 DOI: arxiv-2409.08810

Fan Chen, Jinghua Wang, Huan-Feng Duan

{"title":"A novel volume of fluid ghost-cell immersed boundary method for free surface flow interacting with structures","authors":"Fan Chen, Jinghua Wang, Huan-Feng Duan","doi":"arxiv-2409.08810","DOIUrl":"https://doi.org/arxiv-2409.08810","url":null,"abstract":"This paper presents a novel volume of fluid ghost-cell immersed boundary (IB)\u0000method for two-phase free surface flow interacting with structures. To\u0000circumvent the disturbance occurring around the intersection area of the IB and\u0000free surface when using the interpolation method for variable reconstruction,\u0000the fluid-structure interaction is firstly considered with the orthogonal IB by\u0000mimicking the imposition of boundary conditions in the body-conformal grid\u0000method. Treatments are subsequently performed to account for the non-orthogonal\u0000effect in accurately simulating the FSI, including the newly proposed\u0000flux-scaling and IB velocity re-evaluation methods. Further, a variable\u0000smoothing process and a flux correction method are adapted to handle moving\u0000boundary cases. Based on OpenFOAM, a two-phase flow solver has been developed.\u0000Both stationary and moving immersed boundary cases are used for validations.\u0000The numerical results reasonably agree with the corresponding laboratory data\u0000and other numerical simulation results, demonstrating the disturbance being\u0000effectively depressed and the solver's accuracy in capturing fluid-structure\u0000interactions involving free surface flow.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"198 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142267650","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

On the performances of standard and kinetic energy preserving time-integration methods for incompressible-flow simulations 关于不可压缩流模拟的标准和动能保存时间积分法的性能

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-13 DOI: arxiv-2409.08851

Marco Artiano, Carlo De Michele, Francesco Capuano, Gennaro Coppola

引用次数: 0

Hydrodynamics of an oscillating cylinder inline with steady current 稳流直列摆动圆柱体的流体力学

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-13 DOI: arxiv-2409.08528

Chengjiao Ren, Feifei Tong, Fei He, Liang Cheng

{"title":"Hydrodynamics of an oscillating cylinder inline with steady current","authors":"Chengjiao Ren, Feifei Tong, Fei He, Liang Cheng","doi":"arxiv-2409.08528","DOIUrl":"https://doi.org/arxiv-2409.08528","url":null,"abstract":"Wake and force characteristics of an oscillating cylinder in inline steady\u0000currents are investigated numerically over a wide parameter space of\u0000dimensionless oscillation amplitude ($A^* = 0.01 - 0.50$) and wavelength\u0000($lambda^* = 0.4 - 25$) at a fixed Reynolds number $Re = 500$. Fundamental\u0000issues addressed in this study are the interactions of wakes induced by steady\u0000approaching flow and cylinder oscillations and the influences of the governing\u0000parameters of $A^$ and $lambda^$ on such interactions. Whilst the collinear\u0000flow is dominated by wakes induced by cylinder oscillation at $lambda^* leq\u00001.5$ and steady current at $lambda^* geq 10$, it exhibits characteristics of\u0000nonlinear interactions of wakes induced by the cylinder oscillation and steady\u0000current at $lambda^* = 1.5 - 10$, such as the formation of multiple\u0000synchronized modes interleaved with desynchronized modes. The synchronized mode\u0000varies with both $lambda^$ and $A^$, forming an inclined Arnold's tongue\u0000across $lambda^-A^$ space. There is a wide variability of the vortex shedding\u0000pattern in each synchronized mode. Variations of different hydrodynamic force\u0000coefficients with $lambda^$ and $A^$ are investigated with physical\u0000interpretations based on the wake characteristics. The applicability of the\u0000Morison equation in predicting inline force fluctuations is examined. We found\u0000that the Morison equation shows reasonable accuracy only for a small range of\u0000$lambda^* leq 1.5$. Beyond this range, its performance deteriorates due to\u0000the influence of steady current on wake characteristics.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142267648","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

Deep reinforcement learning for tracking a moving target in jellyfish-like swimming 在水母式游泳中跟踪移动目标的深度强化学习

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-13 DOI: arxiv-2409.08815

Yihao Chen, Yue Yang

{"title":"Deep reinforcement learning for tracking a moving target in jellyfish-like swimming","authors":"Yihao Chen, Yue Yang","doi":"arxiv-2409.08815","DOIUrl":"https://doi.org/arxiv-2409.08815","url":null,"abstract":"We develop a deep reinforcement learning method for training a jellyfish-like\u0000swimmer to effectively track a moving target in a two-dimensional flow. This\u0000swimmer is a flexible object equipped with a muscle model based on torsional\u0000springs. We employ a deep Q-network (DQN) that takes the swimmer's geometry and\u0000dynamic parameters as inputs, and outputs actions which are the forces applied\u0000to the swimmer. In particular, we introduce an action regulation to mitigate\u0000the interference from complex fluid-structure interactions. The goal of these\u0000actions is to navigate the swimmer to a target point in the shortest possible\u0000time. In the DQN training, the data on the swimmer's motions are obtained from\u0000simulations conducted using the immersed boundary method. During tracking a\u0000moving target, there is an inherent delay between the application of forces and\u0000the corresponding response of the swimmer's body due to hydrodynamic\u0000interactions between the shedding vortices and the swimmer's own locomotion.\u0000Our tests demonstrate that the swimmer, with the DQN agent and action\u0000regulation, is able to dynamically adjust its course based on its instantaneous\u0000state. This work extends the application scope of machine learning in\u0000controlling flexible objects within fluid environments.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142267645","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

Principles of hydrodynamic particle manipulation in internal Stokes flow 内斯托克斯流中的流体动力粒子操纵原理

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-13 DOI: arxiv-2409.08452

Xuchen Liu, Partha Kumar Das, Sascha Hilgenfeldt

引用次数: 0

Covariant algebraic Reynolds stress modelling of curvature effects in high-Reynolds-number Taylor--Couette turbulence 高雷诺数泰勒--库埃特湍流中曲率效应的协变代数雷诺应力模型

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-13 DOI: arxiv-2409.08471

Kazuhiro Inagaki, Yasufumi Horimoto

{"title":"Covariant algebraic Reynolds stress modelling of curvature effects in high-Reynolds-number Taylor--Couette turbulence","authors":"Kazuhiro Inagaki, Yasufumi Horimoto","doi":"arxiv-2409.08471","DOIUrl":"https://doi.org/arxiv-2409.08471","url":null,"abstract":"Nearly constant mean angular momentum profiles are widely observed in curved\u0000turbulent flows, including the bulk region of Taylor--Couette (TC) flows, where\u0000the inner and outer cylinders have weakly counter-rotating and co-rotating\u0000conditions. For high-Reynolds-number TC flows under these conditions, both the\u0000bulk and boundary layers become turbulent without Taylor rolls, referred to as\u0000the featureless ultimate regime (UR). In this study, we examine\u0000Reynolds-averaged Navier--Stokes (RANS) models to predict the nearly constant\u0000mean angular velocity as a one-dimensional problem in the featureless UR of TC\u0000turbulence. High-Reynolds-number experiments of TC turbulence are performed for\u0000reference, where the radius ratio is $eta = r_mathrm{in}/r_mathrm{out} =\u00000.732$ and angular velocity ratio $a = -omega_mathrm{out}/omega_mathrm{in}$\u0000is in the range $-0.5 le a le 0.1$. Verification of the RANS model using the\u0000algebraic Reynolds stress model (ARSM) suggests that convection of the Reynolds\u0000stress is essential for predicting the angular momentum profile. We introduce\u0000the Jaumann derivative as a covariant time derivative to develop ARSMs that\u0000incorporate the convection effect in a covariant manner. The proposed ARSM\u0000using the Jaumann derivative of the term composed of the strain and vorticity\u0000tensors successfully predicts the nearly constant mean angular momentum for a\u0000wide range of angular velocity ratios in the co-rotating case. The modelling\u0000approach incorporating time-derivative terms is a candidate for expressing\u0000curvature effects while satisfying the covariance of the Reynolds stress\u0000tensor.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142267649","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

PINNfluence: Influence Functions for Physics-Informed Neural Networks PINNfluence：物理信息神经网络的影响函数

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-13 DOI: arxiv-2409.08958

Jonas R. Naujoks, Aleksander Krasowski, Moritz Weckbecker, Thomas Wiegand, Sebastian Lapuschkin, Wojciech Samek, René P. Klausen

引用次数: 0

Solid-Fluid Interaction on Particle Flow Maps 粒子流图上的固液相互作用

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-13 DOI: arxiv-2409.09225

Duowen Chen, Zhiqi Li, Junwei Zhou, Fan Feng, Tao Du, Bo Zhu

引用次数: 0

Event-based reconstruction of time-resolved centreline deformation of flapping flags 基于事件的拍旗中心线变形时间分辨重建

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-13 DOI: arxiv-2409.08939

Gaetan Raynaud, Karen Mulleners

{"title":"Event-based reconstruction of time-resolved centreline deformation of flapping flags","authors":"Gaetan Raynaud, Karen Mulleners","doi":"arxiv-2409.08939","DOIUrl":"https://doi.org/arxiv-2409.08939","url":null,"abstract":"High-speed imaging is central to the experimental investigation of fast\u0000phenomena, like flapping flags. Event-based cameras use new types of sensors\u0000that address typical challenges such as low illumination conditions, large data\u0000transfer, and the trade-off between increasing repetition rate and measurement\u0000duration more efficiently and at reduced costs compared to classical\u0000frame-based fast cameras. Event-based cameras output unstructured data that\u0000frame-based algorithms can not process. This paper proposes a general method to\u0000reconstruct the motion of a slender object similar to the centreline of a\u0000flapping flag from raw streams of event data. Our algorithm relies on a coarse\u0000chain-like structure that encodes the current state of the line and is updated\u0000by the occurrence of new events. The algorithm is applied to synthetic data,\u0000generated from known motions, to demonstrate that the method is accurate up to\u0000one percent of error for tip-based, shape-based, and modal decomposition\u0000metrics. Degradation of the reconstruction accuracy due to simulated defects\u0000only occurs when the defect intensities become more than two orders of\u0000magnitude larger than the values expected in experiments. The algorithm is then\u0000applied to experimental data of flapping flags, and we obtain relative errors\u0000below one percent when comparing the results with the data from laser distance\u0000sensors. The reconstruction of line deformation from event-based data is\u0000accurate and robust, and unlocks the ability to perform autonomous measurements\u0000in experimental mechanics.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142267644","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

The stability of stratified horizontal flows of carbon dioxide at supercritical pressures 超临界压力下二氧化碳分层水平流动的稳定性

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-13 DOI: arxiv-2409.08804

Marko Draskic, Jerry Westerweel, Rene Pecnik

{"title":"The stability of stratified horizontal flows of carbon dioxide at supercritical pressures","authors":"Marko Draskic, Jerry Westerweel, Rene Pecnik","doi":"arxiv-2409.08804","DOIUrl":"https://doi.org/arxiv-2409.08804","url":null,"abstract":"Fluids at supercritical pressures exhibit large variations in density near\u0000the pseudo critical line, such that buoyancy plays a crucial role in their\u0000fluid dynamics. Here, we experimentally investigate heat transfer and\u0000turbulence in horizontal hydrodynamically developed channel flows of carbon\u0000dioxide at 88.5 bar and 32.6{deg}C, heated at either the top or bottom surface\u0000to induce a strong vertical density gradient. In order to visualise the flow\u0000and evaluate its heat transfer, shadowgraphy is used concurrently with surface\u0000temperature measurements. With moderate heating, the flow is found to strongly\u0000stratify for both heating configurations, with bulk Richardson numbers Ri\u0000reaching up to 100. When the carbon dioxide is heated from the bottom upwards,\u0000the resulting unstably stratified flow is found to be dominated by the\u0000increasingly prevalent secondary motion of thermal plumes, enhancing vertical\u0000mixing and progressively improving heat transfer compared to a neutrally\u0000buoyant setting. Conversely, stable stratification, induced by heating from the\u0000top, suppresses the vertical motion leading to deteriorated heat transfer that\u0000becomes invariant to the Reynolds number. The optical results provide novel\u0000insights into the complex dynamics of the directionally dependent heat transfer\u0000in the near-pseudo-critical region. These insights contribute to the reliable\u0000design of heat exchangers with highly property-variant fluids, which are\u0000critical for the decarbonisation of power and industrial heat. However, the\u0000results also highlight the need for further progress in the development of\u0000experimental techniques to generate reliable reference data for a broader range\u0000of non-ideal supercritical conditions.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"102 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142267647","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