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Numerical investigation of flow-induced deformation along the human respiratory upper airway

JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY 2015年第12期29卷 5267-5272页

作者： Kim, So-Hee Chung, Seung-Kyu Na, Yang Konkuk Univ Dept Mech Engn Seoul 143701 South Korea Sungkyunkwan Univ Sch Med Samsung Med Ctr Dept Otorhinolaryngol Head & Neck Surg Seoul South Korea

fluid-structure interaction (FSI) was considered to predict the compliant wall deformation in human respiratory upper airway. Timedependent airflow was analyzed by the large eddy simulation technique. The surface deformation along the respiratory airway was evaluated by linear structural analysis via a unidirectional FSI approach without considering the tissues, muscles, and bones surrounding the airway. Human subcutaneous tissue and corresponding animal data were used to establish the mechanical properties of the inner tissues throughout the respiratory airway. Although the lowest local pressure was found near the junction between the larynx and trachea, a relatively large deformation was observed in the distributed area between the nasal cavity and trachea. Furthermore, the mean velocity at the location of maximum deformation is negatively correlated with the pressure but is positively correlated with the deformation amount over time.

关键词： Compliant wall deformation computational fluid dynamics simulation Flow structure interaction Respiratory upper airway Wall pressure

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Experimental Investigation of a Mach 3.5 Waverider Designed Using computational fluid dynamics

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AIAA JOURNAL 2015年第6期53卷 1590-1601页

作者： Lobbia, Marcus A. Suzuki, Kojiro Univ Tokyo Dept Adv Energy Kashiwa Chiba 2778561 Japan

A computational-fluid-dynamics-based waverider design approach is discussed, which can allow arbitrary generating flowfields (for which no analytical solution exists) to be used in waverider design. To validate this design technique, a waverider with a lift-to-drag ratio L/D of 2.62 was designed and optimized using a Mach 3.5 conical flowfield for a series of wind-tunnel experiments. A payload volume constraint was implemented such that an aerodynamically optimized design could be generated that met wind-tunnel installation and model manufacturability requirements. A variety of experiments at both on- and off-design conditions were performed using a blowdown supersonic wind tunnel. Measurements were obtained using a sting balance, pressure-sensitive paint (with an a priori temperature compensation approach), and schlieren and oil-flow visualization. For comparison with the experimental results, computational-fluid-dynamics simulations of the configuration were also performed;the design L/D and aerodynamic coefficients were predicted by the computational fluid dynamics and design code to within 11% of the sting-balance measurements. Additionally, the schlieren and oil-flow visualization results showed the attached shock-wave characteristics and reproduction of the conical generating flowfield by the waverider at on-design conditions. Experiments at Mach 3 and 4 conditions indicated a change in L/D of less than 3% for the waverider tested, and the design also demonstrated a positive L/D for the full angle of attack range tested (from -8 to 8deg).

关键词： Waverider computational fluid dynamics simulation Pressure Sensitive Paint Aerodynamic Coefficients Aerodynamic Efficiency Supersonic Wind Tunnels Stagnation Temperature Attached Shock Wave Lift to Drag Ratio Hypersonic Flows

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Influence of Torque Ratio on Counter-Rotating Open-Rotor Interaction Noise

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AIAA JOURNAL 2015年第9期53卷 2726-2738页

作者： Delattre, G. Falissard, F. Off Natl Etud & Rech Aerosp Appl Aerodynam Dept F-92190 Meudon France Off Natl Etud & Rech Aerosp Aeroacoust Dept F-92322 Chatillon France

This paper investigates the influence of the torque ratio, at constant total thrust, on the interaction noise of a generic counter-rotating open rotor in pusher configuration. It is shown that torque ratio has a small influence on the open-rotor aerodynamic performance but a strong impact on interaction noise at takeoff condition. The noise source mechanisms are investigated in detail and linked with the characteristics of the front rotor blade-tip vortices. Tip vortex characteristics are detailed and compared with analytical vortex models. It is verified that torque ratio variation has no strong impact on the open-rotor aerodynamic performance at cruise condition.

关键词： Vortex Structure Power Coefficient Aerodynamic Efficiency Pusher Configuration Blade Passing Frequency computational fluid dynamics simulation Overall Sound Pressure Level Blade Vortex Interaction Reynolds Averaged Navier Stokes Blade Loading

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The influence of reactor fluid-dynamics during zeolite synthesis: The synthesis and the cracking activity of hierarchical ERS-10 A zeolite

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JOURNAL OF CATALYSIS 2015年 329卷 307-316页

作者： Carati, A. Bennardo, A. Montanari, E. Zanardi, S. Rizzo, C. Millini, R. Bellussi, G. Eni Spa Res & Technol Innovat Dept Downstream Labs I-20097 San Donato Milanese MI Italy

Zeolite ERS-10 crystallizes with different structural arrangements and morphologies. In particular, ERS-10 A shows interesting specific surface area and peculiar core-shell morphology, giving a hierarchical porous structure generated by NES zeolite nanocrystals epitaxially grown on a disordered substrate constituted by an intergrowth of NON-EUO-NES-EEI zeolite. But the synthesis of this catalyst is not straightforward: the fluidodynamics of the reagent mixture during ERS-10 A formation plays a pivotal role on the structure of the final product. computational fluid Dynamic simulations allowed to define the stirring system, the fluid motion, the liquid and reagent distribution favorable to the obtainment of the desired phase. High stirring rate during the silica source (tetraethyl-ortosilicate) addition and hydrolysis is required to permit homogeneous distribution of reagents and the crystallization of pure ERS-10 A. The catalytic properties of ERS-10 A are compared with those of FAU and MFI zeolites in the cracking of methylcyclohexane. The behavior of ERS-10 A is in the middle between medium and large pore-zeolites, in agreement with highly accessible active sites, due to its peculiar hierarchical micro-mesoporous system. (C) 2015 Elsevier Inc. All rights reserved.

关键词： Zeolite ERS-10 Hierarchical computational fluid dynamics simulation Methylcyclohexane cracking

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Stability, Receptivity, and Sensitivity Analyses of Buffeting Transonic Flow over a Profile

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AIAA JOURNAL 2015年第7期53卷 1980-1993页

作者： Sartor, Fulvio Mettot, Clement Sipp, Denis Univ Liverpool Liverpool L63 3GH Merseyside England St Gobain Res F-93300 Aubervilliers France Off Natl Etud & Rech Aerosp French Aerosp Lab F-92190 Meudon France

A transonic flow over the OAT15A supercritical profile is considered. The interaction between the shock wave and the turbulent boundary layer is investigated through numerical simulation and global stability analysis for a wide range of angles of attack. Numerical simulations are in good agreement with previous studies and manage to reproduce the high-amplitude self-sustained shock oscillations known as shock buffet. In agreement with previous results, it is found that the buffet phenomenon is driven by an unstable global mode of the linearized Navier-Stokes equations. Analysis of the adjoint global mode reveals that the flow is most receptive to harmonic forcings on the suction side of the profile, within the boundary layer upstream of the shock foot, in the recirculation bubble downstream of the shock foot, and on the right characteristic that impinges the shock foot. An eigenvalue sensitivity analysis shows that a steady streamwise force applied either in the boundary layer or in the recirculation region, a steady cooling of the boundary layer, or a steady source of eddy viscosity (a mechanical vortex generator for example) all lead to stabilization of the buffet mode. Finally, pseudoresonance phenomena have been analyzed by performing a singular-value decomposition of the global resolvent, which revealed that, besides the low-frequency shock unsteadiness, the flow also undergoes medium-frequency unsteadiness, linked to Kelvin-Helmholtz-type instability. Such results are reminiscent of the medium-frequency perturbations observed in more traditional shock wave/boundary-layer interactions.

关键词： Supersonic Flow Critical Angle of Attack Laminar Turbulent Transition Shock Waves computational fluid dynamics simulation Flow Characteristics Singular Value Decomposition Vortex Generators Navier Stokes Equations Sensitivity Analysis

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CFD simulation for secondary breakup of coal-water slurry drops using OpenFOAM

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FUEL PROCESSING TECHNOLOGY 2015年 132卷 153-163页

作者： Tavangar, Saeed Hashemabadi, Seyed Hassan Saberimoghadam, Ali Iran Univ Sci & Technol Sch Chem Engn CFD Res Lab Tehran 16846 Iran

The main objective of this study is to gain insight into dynamic behavior of coal-water slurry (CWS) drops during secondary breakup. In the case of Bingham liquids (CWS) considered here, this endeavor requires a thorough understanding of the influence of the shear-thinning and viscoplastic fluid rheology on the flow inside the deforming drops. In numerical analysis, a coupled technique including Large Eddy simulation (LES) and smoothed volume of fluid (VOF) was used with a dynamic adaptive mesh. The effects of variations in secondary breakup and viscoplastic liquid theological parameters on Sauter mean diameter (SMD), droplet aspect ratio, and dynamic average viscosity were studied in detail. The results show good predictions for the breakup regimes. Moreover, an effective constant viscosity leading to a similar Newtonian breakup regime was detected in all cases. According to the analogy between secondary and primary breakups, the results can be used to better understand the CWS jet breakup. (C) 2014 Elsevier B.V. All rights reserved.

关键词： Coal water slurry drops Secondary breakup computational fluid dynamics simulation LES/VOF OpenFOAM (R)

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Ni-Al2O3/Ni-foam catalyst with enhanced heat transfer for hydrogenation of CO2 to methane

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AICHE JOURNAL 2015年第12期61卷 4323-4331页

作者： Li, Yakun Zhang, Qiaofei Chai, Ruijuan Zhao, Guofeng Liu, Ye Lu, Yong Cao, Fahai E China Normal Univ Sch Chem & Mol Engn Shanghai Key Lab Green Chem & Chem Proc Shanghai 200062 Peoples R China E China Univ Sci & Technol Coll Chem Engn Shanghai 200237 Peoples R China

Monolithic Ni-Al2O3/Ni-foam catalyst is developed by modified wet chemical etching of Ni-foam, being highly active/selective and stable in strongly exothermic CO2 methanation process. The as-prepared catalysts are characterized by x-ray diffraction scanning electron microscopy, inductively coupled plasma atomic emission spectrometry, and H-2-temperature programmed reduction-mass spectrometry. The results indicate that modified wet chemical etching method is working efficiently for one-step creating and firmly embedding NiO-Al2O3 composite catalyst layer (approximate to 2 m) into the Ni-foam struts. High CO2 conversion of 90% and high CH4 selectivity of >99.9% can be obtained and maintained for a feed of H-2/CO2 (molar ratio of 4/1) at 320 degrees C and 0.1 MPa with a gas hourly space velocity of 5000 h(-1), throughout entire 1200 h test over 10.2 mL such monolithic catalysts. computational fluid dynamics calculation and experimental measurement consistently confirm a dramatic reduction of hotspot temperature due to enhanced heat transfer. (c) 2015 American Institute of Chemical Engineers

关键词： heterogeneous catalysis structured catalyst methanation foam computational fluid dynamics simulation

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A Comprehensive computational fluid dynamics Study of Droplet-Film Impact and Heat Transfer

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CHEMICAL ENGINEERING & TECHNOLOGY 2015年第9期38卷 1565-1573页

作者： Jiang, Fan Wang, Yijun Xiang, Jianhua Liu, Zhenzhang Guangzhou Univ Sch Mech & Elect Engn Guangzhou 510006 Guangdong Peoples R China

The Eulerian multiphase model and continuum surface force (CSF) are employed to simulate the liquid droplet impinging onto a solid wall with a pre-existing thin film of the same liquid. The numerical results are compared with the experimental data reported in the literature, indicating a reasonable matching. The flow field and splashing behavior of a droplet impinging onto a liquid film are analyzed. The reason for the edge of the crown to eject into secondary drops is found. The splashing behavior can be influenced by the impacting velocity and fluid properties. The effects of impact velocity, droplet diameter, depth of film, liquid property, and droplet and wall temperature on the heat removal are investigated. Numerical results demonstrate that an increase in impact velocity, droplet diameter, film depth, cooling droplet, and wall temperature enhances the dissipated heat. These results can provide a reference for designing spray-cooling systems.

关键词： computational fluid dynamics simulation Droplet-film impact Heat transfer Two-phase flow

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Effects of Restitution and Specularity Coefficients on Solid-Liquid fluidized BedHydrodynamics

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CHEMICAL ENGINEERING & TECHNOLOGY 2015年第10期38卷 1827-1836页

作者： Ehsani, Mehran Movahedirad, Salman Shahhosseini, Shahrokh Ashtiani, Mahshid Iran Univ Sci & Technol Sch Chem Engn Proc Simulat & Control Res Lab Tehran Iran Iran Univ Sci & Technol Sch Chem Engn Tehran Iran

An Eulerian-Eulerian two-fluid model in combination with the kinetic theory of granular flow was applied to simulate a solid-liquid fluidized bed filled with stainless-steel particles. The drag model of Gidaspow used in computational fluid dynamics simulations proved to be the appropriate model for predicting the bed hydrodynamics. The effect of the restitution coefficient of the particles on the bed hydrodynamics was investigated numerically. For the solid phase wall boundary condition according to Johnson and Jackson a specularity coefficient was introduced and evaluated. The change in specularity coefficient did not affect considerably the bed behavior at the middle part, but at the walls it significantly influenced the granular temperature. For specularity coefficients more than 0.5 the results do not change noticeably.

关键词： computational fluid dynamics simulation fluidized bed Hydrodynamics Restitution coefficient Specularity coefficient

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dynamics of drops - Formation, growth, oscillation, detachment, and coalescence

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ADVANCES IN COLLOID AND INTERFACE SCIENCE 2015年 222卷 413-424页

作者： Karbaschi, M. Rahni, M. Taeibi Javadi, A. Cronan, C. L. Schano, K. H. Faraji, S. Won, J. Y. Ferri, J. K. Kraegel, J. Miller, R. Max Planck Inst Colloids & Interfaces Potsdam Germany Shatif Univ Technol Tehran Iran Univ Tehran Tehran Iran Cronan Creat Solut LLC Milwaukee WI USA Gamma Serv Berlin Germany Lafayette Coll Easton PA 18042 USA

Single drops or bubbles are frequently used for the characterization of liquid fluid interfaces. Their advantage is the small volume and the various protocols of their formation. Thus, several important methods are based on single drops and bubbles, such as capillary pressure and profile analysis tensiometry. However, these methods are often applied under dynamic conditions, although their principles are defined under equilibrium conditions. Thus, specific attention has to be paid when these methods are used beyond certain limits. In many cases, computational fluid dynamics (CFD) simulations have allowed researchers, to extend these limits and to gain important information on the interfacial dynamics. Examples discussed here are the capillary pressure tensiometry used for short time and profile analysis tensiometry for long time dynamic interfacial tension measurements, the oscillating drop methods for measuring dilational visco-elasticity. For measuring the coalescence of two drops the liquid dynamics of the subsequently formed liquid bridges have to be considered. In this paper, a thorough review of important experimental and computational findings, related to the dynamics of drops, including its formation, growth, oscillation, detachment, and coalescence is presented. Emphasis is however on some selected important developments. In addition, the paper tries to predict the main directions of advancement in interfacial research for the near future. (C) 2014 Elsevier B.V. All rights reserved.

关键词： Drop dynamics Drop growing and oscillation Drops coalescence and drop-drop interactions dynamics of liquid bridges Drop-based experimental techniques computational fluid dynamics simulation

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