Volume 2: Computational Fluid Dynamics最新文献_第6页

Cavitation-Induced Interface Instability of Droplet Between Plates 板间液滴的空化界面不稳定性

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5360

Hongchen Li, Jingzhu Wang, Yiwei Wang

{"title":"Cavitation-Induced Interface Instability of Droplet Between Plates","authors":"Hongchen Li, Jingzhu Wang, Yiwei Wang","doi":"10.1115/ajkfluids2019-5360","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5360","url":null,"abstract":"\u0000 Interface instability of droplet and formation of the liquid jet caused by internal volume oscillation are directly related to liquid pumping and mixing of microfluidic devices. Complex morphology jet enables liquid shaping, which is advantageous for industrial applications and biomedical engineering. In this study, the interface instability of cylindrical droplet between plates is investigated. The problem is analyzed through numerical simulation and experimentation. In the experiment, a single-pulse laser is used to generate cavitation at the center of the cylindrical droplet between two polymethyl methacrylate plates, and the physical progress is captured by high-speed photography. A compressible two-phase solver in the open source code OpenFOAM is used to simulate the 3D progress of bubble pulsation and droplet jet in consideration of viscosity and surface tension. Numerical methods adopt large eddy simulation. Results show that the interface density gradient is not collinear with the pressure gradient due to the shock wave impact and the bubble pulsation, that is, the baroclinic effect is the main cause of the instability at the droplet interface. The mechanism of the radial jet formation in the first period of bubble pulsation is closely related to the interface instability. A pair of vortex rings is formed under the influence of instability, thereby causing a stacking phenomenon on the jet head and eventually being cut. Affecting factors of the instability of the droplet interface are discussed. A high instability intensity of the droplet interface can be caused by a large initial bubble energy and a small contact angle. The instability strength of the droplet interface and the mode of jet formation are very sensitive to the curvature of the initial droplet shape. Relevant results may provide a reference for further understanding of interface instability and related engineering applications.","PeriodicalId":346736,"journal":{"name":"Volume 2: Computational Fluid Dynamics","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125518503","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

Control of Air-Ventilated Cavity Under Ship Hull in Abnormal Waves 异型波浪下船体通风空腔的控制

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-4619

K. Matveev

引用次数: 1

CFD DEM Analysis of a Dry Powder Inhaler 干粉吸入器的CFD DEM分析

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-4771

Antara Badhan, V. Kotteda, Vinod Kumar

{"title":"CFD DEM Analysis of a Dry Powder Inhaler","authors":"Antara Badhan, V. Kotteda, Vinod Kumar","doi":"10.1115/ajkfluids2019-4771","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4771","url":null,"abstract":"\u0000 Dry powder inhalers (DPIs), used as a means for pulmonary drug delivery, typically contain a combination of active pharmaceutical ingredient (API) and significantly larger carrier particles. The micro-sized drug particles — which have a strong propensity to aggregate and poor aerosolization performance — mixed with significantly large carrier particles that are unable to penetrate the mouth-throat region to deagglomerate and entrain the smaller API particles in the inhaled airflow. The performance of a DPI, therefore, depends on entrainment the carrier-API combination particles and the time and thoroughness of the deagglomeration of the individual API particles from the carrier particles. Since DPI particle transport is significantly affected by particle-particle interactions, very different particles sizes and shapes, various forces including electrostatic and van der Waals forces, they present significant challenges to Computational Fluid Dynamics (CFD) modelers to model regional lung deposition from a DPI. In the current work, we present a novel high fidelity CFD discrete element modeling (CFD-DEM) and sensitivity analysis framework for predicting the transport of DPI carrier and API particles. The work integrates exascale capable CFD-DEM and sensitivity analysis capabilities by leveraging the Department of Energy (DOE) laboratories libraries: Multiphase Flow Interface Flow Exchange (MFiX) for CFD-DEM, and Trilinos for leading-edge portable/scalable linear algebra. We carried out a sensitivity analysis of various formulation properties and their effects on particle size distribution with Dakota, an open source software designed to exploit High-Performance Computing (HPC) capabilities of a massively parallel supercomputer. We developed wrappers to exchange information among these state-of-the-art tools for DPI.","PeriodicalId":346736,"journal":{"name":"Volume 2: Computational Fluid Dynamics","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116167328","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: 1

A Numerical Investigation of Heat and Mass Transfer in Air-Cooled Proton Exchange Membrane Fuel Cells 气冷质子交换膜燃料电池传热传质的数值研究

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5419

T. Berning

引用次数: 2

Study of Enhanced Self Mixing in Ferrofluid Flow in an Elbow Channel Under the Influence of Non-Uniform Magnetic Field 非均匀磁场影响下弯管内铁磁流体增强自混合的研究

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5546

Nadish Anand, R. Gould

{"title":"Study of Enhanced Self Mixing in Ferrofluid Flow in an Elbow Channel Under the Influence of Non-Uniform Magnetic Field","authors":"Nadish Anand, R. Gould","doi":"10.1115/ajkfluids2019-5546","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5546","url":null,"abstract":"\u0000 This paper investigates numerically the various parameters dictating the vortical (self)-mixing induced by a non-uniform magnetic field in a ferrofluid flow in an elbow channel. The elbow bend region of the channel has two current carrying conductors placed symmetrically and parametrically from the channel and are used to generate a non-uniform magnetic field. The ferrofluid is assumed to be pre-magnetized, isothermal and electrically non-conductive as it enters the channel and has a prescribed inlet magnetization and temperature. The mixing efficiency is characterized by introducing different mixing scalars based on velocity of the fluid and are compared in order to determine the overall suitability of each scalar to quantify the flow vortical (self)-mixing. Parametric studies were performed by varying parameters influencing the magnetic field and the initial flow field. This resulted in variations in non-dimensional groups which control different aspects of the flow and helped establish their relationship with mixing efficiency. It was found that at higher Reynolds numbers the flow mixing induced by the lateral gradient in the Kelvin Body Force (KBF) dissipates and higher electrical inputs are required to sustain mixing in the flow. The effects of mixing enhancement on the pressure gradient across the channel was also established, along with the introduction of an enhanced viscosity term which is due to the non-collinearity of the magnetization vector and the magnetic field vector.","PeriodicalId":346736,"journal":{"name":"Volume 2: Computational Fluid Dynamics","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126968623","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: 2

A Finite Element Based Partitioned Coupling Method for the Simulation of Flow-Induced Fiber Motion 基于有限元的流致光纤运动模拟分区耦合方法

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5096

Diwei Zhang, Xiaobo Peng, Dongdong Zhang

引用次数: 0

An Evaluation of Open Source CFD for Study of Aerodynamics of Vehicle Platooning 基于开源CFD的车辆队列空气动力学研究

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5130

T. Farid, A. Shakeel, M. Sajid

{"title":"An Evaluation of Open Source CFD for Study of Aerodynamics of Vehicle Platooning","authors":"T. Farid, A. Shakeel, M. Sajid","doi":"10.1115/ajkfluids2019-5130","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5130","url":null,"abstract":"\u0000 The ever-growing road congestion and safety hazards induced by conventional highways has inspired the development of automated highways which provides four key benefits: fuel economy, environmental protection, road safety and smooth traffic flow. Vehicle platooning is a vital component of automated highways which contributes directly to these four benefits with its sequence of closely spaced leader-follower vehicle configuration by taking advantage of the ‘slip-stream’ effect to minimize the aerodynamic drag. Exploratory studies into platooning parameters, vehicle spacing, speeds and number of vehicles, have proven to be prohibitive expensive both computationally and experimentally due to the complexity of tests and the large number of test cases. In recent years, OpenFOAM® an independently developed, supported and documented open-source toolbox has gained popularity by offering a lower cost alternative to leading commercial CFD products. This paper summarizes the results from a computational study of autonomous vehicle platoons and the capability of OpenFOAM® to substitute leading commercial CFD solutions currently used to support vehicle aerodynamic development. This study investigates the aerodynamic characteristics of a 4-SUV platoon at inter-vehicle distances ranging from 0.25 to 1 SUV length at a constant speed of 23 m/s. Trends of the predicted aerodynamic drag coefficients (Cd) are then compared against experimental data from published literature as well as the results obtained from a leading commercial CFD package.","PeriodicalId":346736,"journal":{"name":"Volume 2: Computational Fluid Dynamics","volume":"426 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122233984","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: 2

Numerical Simulation of Inline Arrangement of Spheroid Particles in Different Orientations 不同方向球颗粒排列的数值模拟

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-4623

A. Jamil, E. Uddin, A. Zaidi, Zaib Ali, J. Aslam, S. O. Gilani

{"title":"Numerical Simulation of Inline Arrangement of Spheroid Particles in Different Orientations","authors":"A. Jamil, E. Uddin, A. Zaidi, Zaib Ali, J. Aslam, S. O. Gilani","doi":"10.1115/ajkfluids2019-4623","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4623","url":null,"abstract":"\u0000 The understanding of relative motion between particles of non-spherical shapes is of critical importance in many engineering and natural applications. The flow analysis and later explanation of physics can be used for designing and modification of industrial equipment. In this study, computational fluid dynamics is used to numerically solve two-dimensional steady fluid flow for two tandem spheroid particles. The parameters which are varied in simulations are combined effect of Reynolds number (Re), axis ratio (e), inter particle distance (S), size ratio (d2/d1) and particle orientation (α) on the flow and drag force for tandem spheroid particles. For reliability of results, domain and grid independence studies are done before performing the actual simulations. Furthermore, simulations results are also benchmarked with the available literature results and good agreement is observed. It is observed in simulations that the drag increases with the increase in size ratio. Drag force is maximum for oblate particles for an axis ratio e = 0.5 and larger inter-particle distance. For trailing prolate particles, the small inter-particle distance induces suction or negative drag. Furthermore, the negative drag on prolate particles at smaller inter-particle distance S = 2 increase with the increase in size ratio d2/d1 from 0.5 to 0.75 and negatively affects the collective drag (Cd1+Cd2). At Re = 50, the trailing particle drag Cd2 is independent with the orientation angle. The effect of orientation of leading particles is important for Re = 100 & 150. At the end of paper, the physics behind the affecting parameters on drag force is explained using inter-particle wakes and fluid structures.","PeriodicalId":346736,"journal":{"name":"Volume 2: Computational Fluid Dynamics","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124431049","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

An Explicit Modeling Approach for Simulating Fluid-Structure Interaction Problems With Immersed-Boundary Finite-Volume Method 浸没边界有限体积法模拟流固耦合问题的显式建模方法

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5212

Yanbo Huang, Shanshan Li, Z. Pan

{"title":"An Explicit Modeling Approach for Simulating Fluid-Structure Interaction Problems With Immersed-Boundary Finite-Volume Method","authors":"Yanbo Huang, Shanshan Li, Z. Pan","doi":"10.1115/ajkfluids2019-5212","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5212","url":null,"abstract":"\u0000 Fluid-structure interaction (FSI) is an important fundamental problem with wide scientific and engineering applications. The immersed boundary method has proved to be an effective way to model the interaction between a moving solid and its surrounding fluid. In this study, a novel modeling approach based on the coupled immersed-boundary and finite-volume method is proposed to simulate fluid-structure interaction problems. With this approach, the whole computational domain is treated as fluid and discretized by only one set of Eulerian grids. The computational domain is divided into solid parts and fluid parts. A goal velocity is locally determined in each cell inside the solid part. At the same time, the hydrodynamic force exerted on the solid structure is calculated by integrating along the faces between the solid cells and fluid cells. In this way, the interaction between the solid and fluid is solved explicitly and the costly information transfer between Lagranian grids and Eulerian grids is avoided. The interface is sharply restricted into one single grid width throughout the iterations. The proposed modeling approach is validated by conducting several classic numerical experiments, including flow past static and freely rotatable square cylinders, and sedimentation of an ellipsoid in finite space. Throughout the three numerical experiments, satisfying agreements with literatures have been obtained, which demonstrate that the proposed modeling approach is accurate and robust for simulating FSI problems.","PeriodicalId":346736,"journal":{"name":"Volume 2: Computational Fluid Dynamics","volume":"136 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123257560","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

Passive Pitching Mechanism of Three-Dimensional Flapping Wings in Hovering Flight 悬停飞行中三维扑翼被动俯仰机理研究

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-4639

Chengyu Li, Junshi Wang, Geng Liu, Xiaolong Deng, Haibo Dong

{"title":"Passive Pitching Mechanism of Three-Dimensional Flapping Wings in Hovering Flight","authors":"Chengyu Li, Junshi Wang, Geng Liu, Xiaolong Deng, Haibo Dong","doi":"10.1115/ajkfluids2019-4639","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4639","url":null,"abstract":"\u0000 Flapping wings of insects can passively maintain a high angle of attack due to the torsional flexibility of wing basal region without the aid of the active pitching motion. However, the lift force generated by such passive pitching motion has not been well explored in the literature. Consequently, there is no clear understanding of how torsional wing flexibility should be designed for optimal performance. In this work, a computational study was conducted to investigate the passive pitching mechanism of flapping wings in hovering flight using a torsional spring model. The torsional wing flexibility was characterized by Cauchy number. The impacts of the inertial effect of wings were evaluated using the mass ratio. The aerodynamic forces and associated unsteady flow structures were simulated by an in-house immersed-boundary-method based computational fluid dynamic solver. A parametric study on the Cauchy number was performed with a Reynolds number of 300 at a mass ratio of 1.0, which covers a wide range of species of insect wings. According to the analysis of the aerodynamic performance, we found that the optimal lift can be achieved at a Cauchy number around 0.16, while the optimal efficiency in terms of lift-to-power ratio was reached at a Cauchy number around 0.3. All the corresponding wing pitching kinematics had a pitching magnitude around 60 degrees with slightly advanced rotation. In addition, 3D wake structures generated by the passive flapping wings were analyzed in detail. The findings of this work could provide important implications for designing more efficient flapping-wing micro air vehicles.","PeriodicalId":346736,"journal":{"name":"Volume 2: Computational Fluid Dynamics","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126465787","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: 2