bluuebunny/crossref_metadata_2025_split huggingface dataset:
PIV and POD Investigations of Coherent Vortices Downstream Circular or Rectangular Obstacles Located Between Two Parallel Plates
Authors: Aloui Fethi , Elawady Amal , Hammad Khaled J. 
Published: November 2019

Abstract
The study is an experimental investigations using PIV. The measurements were obtained by PIV for an unsteady laminar flow across a rectangular channel with a cross-section 300 × 30mm2, in the middle of which is located a cylindrical or a square obstacle. In the case of the cylindrical configuration and due to the confinement, PIV measurements in the range of 40 &lt; Re &lt; 200 clearly show that the von Karman vortex shedding appears at a critical Reynolds number which is about 66. A post-processing of these PIV measurements using the Proper Orthogonal Decomposition (POD) technique is by keeping only the first most energetic six modes, can be used as a filtering process to remove noise from instantaneous velocity signals. In the case of the square obstacle, PIV measurements obtained in the range of 30 &lt; Re &lt; 350 show the absence of vortex detachments and the chaotic behavior of the wake behind the obstacle beyond a certain Reynolds number. By examining the POD post-possessing results, the existence of a dynamic detachments’ regime (instantaneous breaking and coalescence of vortices), can be clearly observed. Given the chaotic behavior of the wake behind the obstacle, the application of the POD filtering process to only the first most energetic modes, cannot lead to good results.
Weakly Nonlinear and High Speed Propagation of Quasi-Monochromatic High Frequency Waves in Compressible Bubbly Liquids
Authors: Yoshimoto Takanori , Kanagawa Tetsuya 
Published: November 2019

Abstract
This study theoretically investigates plane progressive quasi-monochromatic waves in an initially quiescent compressible liquid containing many spherical gas bubbles, on the basis of the derivation of a nonlinear wave equation that represents waves propagating at a high phase velocity induced by taking the effect of liquid compressibility in consideration. The governing equations for bubbly flows are composed of the conservation equations of mass and momentum, the equation of bubble dynamics as radial oscillations, and so on. By using the method of multiple scales with an appropriate choice of set of scaling relations of nondimensional parameters, the nonlinear Schrödinger (NLS) equation with an attenuation term and some correction terms can be derived from the governing equations. The decrease in the group velocity in a far field is then clarified. The dependence of waveform on wavenumber is implied.
Computational Fluid Dynamic Analysis of a Marine Hydrokinetic Crossflow Turbine in Low Reynolds Number Flow
Authors: Doan Minh N. , Alayeto Ivan H. , Kumazawa Kana , Obi Shinnosuke 
Published: November 2019

Abstract
This study focuses on surveying different turbulence models and dynamic mesh techniques to simulate a marine hydrokinetic (MHK) crossflow turbine at Rec ≈ 7,000. While several research projects have shown that studies of MHK devices in low Re flow could still yield interesting and significant results, existing computational fluid dynamic (CFD) simulations were conducted at the chord based Re of 105 ∼ 106. The wake and power production of a laboratory-scaled MHK crossflow turbine were numerically simulated and compared with relevant experimental data. The vertical axis turbine operated in a small flume with 20% blockage ratio and was fabricated by mounting three NACA0012 (2.54 cm chord length) straight blades at a radius of 3.41 cm and 15° pitch angle. Within OpenFOAM environment, blade-resolved models were built with Spalart-Allmaras, k-omega shear stress transport (SST), and k-kl-omega unsteady Reynolds-averaged Navier-Stokes simulation (URANS) in both two and three dimensions. Results from each model were compared with the experimental power measurement and flow field obtained by monoscopic particle image velocimetry (2D PIV). Additionally, four different techniques for moving the solid boundaries (turbine blades) in the unsteady simulation were presented and compared in terms of solution consistency and required computational power. Overset mesh, time-deforming mesh, and moving immersed boundary are all available in this open source environment, beside the common rotating mesh technique, and possess the potential to be applied to a more complicated configuration of turbines.
CFD DEM Analysis of a Dry Powder Inhaler
Authors: Badhan Antara , Kotteda V. M. Krushnarao , Kumar Vinod 
Published: November 2019

Abstract
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.
Experimental Characterization of a Micro-Blower for Flow Control
Authors: Wu Maria , Sullivan Pierre 
Published: November 2019

Abstract
A compact, lightweight, low-power piezoelectric micro-blower was characterized using particle image velocimetry to determine its flow control potential. The micro-blower has been operated in continuous mode as well as in burst mode using two different actuation frequencies. The maximum mean velocity measured with the micro-blower operating in continuous mode was approximately Ūmax = 13 m/s which occurred at the centerline at an approximate stream-wise location of x/d = 4. The velocity profiles in the developed region resemble those of turbulent jets. The momentum-flux from the micro-blower in continuous mode was significantly greater than a typical synthetic jet actuator which was successfully used for flow control, indicating that the micro-blower can impart the necessary momentum to be effective for flow control. With burst mode, the results show that the micro-blower could impart an even greater momentum.
Optimizing Pump Selection for Energy Efficiency Across Multiple Operating Conditions Using True Weighted Efficiency (TWE)
Authors: Dahl Trygve 
Published: November 2019

Abstract
Energy efficiency is emphasized more actively across the pump industry. Legislation in the European Union and in the United States utilize new energy efficiency ranking metrics, but neither of these methods are conveniently applied to customer specified load conditions. True Weighted Efficiency, or TWE, is introduced as a general-purpose, universal pump efficiency metric for pumps operating under multiple operating conditions.
The TWE is derived accurately from first principles, using generalized load profiles that include control curves, multiple discrete operating points based on those control curves, and the time of operation at each operating point.
A pump selection/optimization program is used to numerically demonstrate the TWE method. Various examples are presented, contrasting candidate pumps based on three different optimization strategies. The study reveals that the pump with the best design point efficiency may not be the best choice from a TWE or an evaluated cost perspective.
This method is applicable to rotodynamic or positive displacement pumps operating at fixed or variable speed, on/off operation, throttle control, or by-pass control. and other turbomachinery as well. The TWE methodology, when combined with a pump selection/optimization program, will help practitioners design systems that reduce energy consumption for new or reconfigured pump applications.
Global Stability Analysis on the Spiral-Vortex Mode in the Confined Cavity Flow Between Rotating and Stationary Disks
Authors: Okabayashi Kie , Kodera Yuki , Takeuchi Shintaro , Kajishima Takeo , An Byungjin , Nohmi Motohiko , Obuchi Masashi 
Published: November 2019

Abstract
Global stability analysis (GSA) is applied to a 3D confined cavity flow between rotating and stationary disks (viz., rotor and stator). The Arnoldi method extended for incompressible viscous flow is used together with the eigenvalue spectrum conversion to solve the eigenvalue problem of the GSA. As a first step, the GSA is conducted in an axisymmetric flow, and circular vortices are obtained as eigen modes. Then, the GSA is applied to a flow with circular vortex at a higher Reynolds number, and eigen vectors of spiral vortex are obtained. The result suggests that the GSA shows unstable flows after transition of the baseflow. However, it is necessary to reconsider the convergence of the eigenvalues for the parameters of Arnoldi method.
Reservoir Geomechanical Modeling and Ground Uplift During CO2 Injection Into Khuff Reservoir
Authors: Khan Sikandar , Khulief Yehia , Al-Shuhail Abdullatif 
Published: November 2019

Abstract
In this investigation, coupled-geomechanical modeling is performed using the COMSOL Multiphysics software, during carbon dioxide injection into the deep Khuff carbonate reservoir. Khuff reservoir is a carbonate reservoir that is capped by the low permeability Sudair shale geological layer. The main objective of the study was to evaluate safe values of the carbon dioxide injection parameters for the Khuff reservoir that will act as a benchmark for the similar reservoirs and injection scenarios around the globe. Carbon dioxide was injected for a period of 10 years into the reservoir and the corresponding variations in the reservoir pore-pressure and ground uplift was evaluated. The Mohr-Coulomb failure criterion was utilized to perform the stability analysis for the Khuff reservoir during carbon dioxide injection.
A Numerical Analysis of the Hemodynamic Functionality of Human Coronary Stenosis Under Different Physiologic Conditions and Boundary Condition Formulations
Authors: Fayssal Iyad , Moukalled Fadl 
Published: November 2019

Abstract
Coronary artery disease (CAD) is among the foremost causes for human death worldwide. This study aims at investigating the performance of different boundary condition model types to characterize CAD functional significance. In addition, alternate models to estimate FFR using any different combination of boundary conditions at inlet and outlet were analyzed. In the first type of boundary condition, an outflow resistance model is used combined with a fixed pressure at inlet. In the second model of boundary conditions, constant pressure values are imposed at the domain inlet and outlet/s sections. In the third model, a zero diffusion flux is applied at outlet with a pre-specified flow rate at inlet. Numerical simulations performed on healthy and stenosed idealized and physiological arterial models revealed the superiority of the first type of boundary condition to directly capture the level of ischemia in diseased arteries. However, in this model, special numerical treatment at the outflow boundary is needed to dampen pseudo numerical reflections entering the computational domain. Alternative simple methods are developed to tackle the problem incurred in the second and third types of boundary condition types. The alternate models are effective for carrying extensive parametric studies with minimal computational effort. The new developed methods allow results generated via generic simulations under any specified boundary condition type to correctly estimate CAD functional significance. The obtained surrogate models account for the effects of the patient-specific physiologic parameters and can be easily incorporated without modifying existing CFD codes. Moreover, where it is unfeasible to experimentally incorporate the downstream effects of a given diseased arterial segment, an important aspect the alternative models provide is that they can be easily adopted by experimentalists through building in-vitro arterial models to assess the functional significance of the obstruction caused by the disease and its relation to any given patient specific physiologic parameter.
Heat Transfer and Fluid Flow in Arc-Based Additive Manufacturing
Authors: Zhou Jun 
Published: November 2019

Abstract
Additive manufacturing (AM) is gaining rapid popularity in many industries like automotive, medical, electronics and aerospace due to its flexibility to build parts with complex geometry. Nowadays, laser/electron-beam/arc melting or deposition are commonly used for AM of metallic parts. Melting-solidification and melt flow repeatedly occur in the AM process, which are critical in determining the final shape, precision, and quality of the AM products. In this study, melt flow and heat transfer in arc-based metallic additive manufacturing process are discussed. The key parameters affecting the fluid flow; heat transfer; defect formation; and surface topology of the AM parts are investigated.
Fluid-Structure Interaction Simulation of Lactating Human Breast
Authors: Azarnoosh Jamasp , Hassanipour Fatemeh 
Published: November 2019

Abstract
Extracting milk during breastfeeding is not only caused by intra-oral vacuum pressure by the infant suckling but also is the periodic motion of the infant’s jaw, which is the focus of this study. A Fluid-structure interaction simulation provides a better understanding of the milk flow behavior in the human breast ductal system as the breast interacts with the infant’s oral cavity and jaws. Simulations were performed from the instance of latching and continued for two cycles of periodic tongue motion. The negative vacuum pressure profile was measured from the clinical data and applied in the simulation. The nipple dimensions were obtained using ultrasound images and used as boundary conditions in the simulation. The effect of vacuum pressure and the peripheral pressure on the milk flow behavior in breast ductal system were studied individually. It was observed that the deformation of the ductal system has a critical impact on milk flow behavior and the amount of expressed milk.
On the Low and High Speed Flow of Gases Through Pillow Plate Channels
Authors: Passmann Maximilian , aus der Wiesche Stefan , Kenig Eugeny Y. 
Published: November 2019

Abstract
Low speed and high speed flow phenomena in pillow plate channels are considered. High speed flows were investigated by means of analytical methods and fully three-dimensional computational fluid dynamics (CFD) simulations. The theoretical analysis indicated that a Fanno-type flow model described high speed flow behavior in pillow plate channels reasonably well. Since only wavy walls with smooth profiles were involved, linearized gas dynamics was applied in order to derive similarity laws for the high speed flows. The detailed CFD analysis was used to support the assumption of a Fanno-type flow. The effects of the wavy wall structures on pressure drop and Mach number distribution within the flow path were investigated in detail. The present analysis demonstrates that pillow plate heat exchangers represent promising candidates for high speed turbo machinery applications.
On the Influence of Gas Content on the Rotordynamic Force Coefficients of a Three-Wave (Air in Oil) Annular Seal for Multiple Phase Pumps
Authors: San Andrés Luis , Lu Xueliang , Wu Tingcheng 
Published: November 2019

Abstract
The subsea oil & gas industry efficiently uses multiphase pumps and wet gas compressors to eliminate upstream oil and gas separation stations, hence saving up to 30% in capital expenditures. Subsea multiphase process facilities must operate reliably for extended lengths of time while the wells, as they deplete, produce a process fluid varying from a pure liquid, to a mixture of gas and liquid, and to eventually just gas. The variation of gas volume fraction (GVF), by affecting the leakage and dynamic forced performance of sealing elements, alters turbomachinery performance to produce both an increase in synchronous speed rotor vibrations and a reduction in rotor dynamic stability. Prior laboratory work shows that plain cylindrical surface annular seals operating with a fluid flow in the laminar flow regime produce no direct (centering) stiffness and a large added mass, in particular for the liquid only condition. The early work also advanced a simple three-wave shape seal (akin to lobes) that generates a significant direct stiffness, impervious to GVF as large as 90%, and hence aids to increase the natural frequency of a vertical pump. Dynamic load tests for this wavy-seal configuration operating with a gas in liquid mixture [air in light ISO VG 10 oil] are the subject of this paper that presents dynamic force coefficients vs. excitation frequency (ω) while the shaft turns at a speed (Ω) equal to 3.5 krpm (23.3 m/s surface speed), a typical operating speed for multiphase pumps. The test seal has length L = 43 mm, diameter D = 127 mm, and a mean radial clearance cm = 0.191 mm. For operation with a pure liquid (GVF = 0), the seal force coefficients are frequency independent, thus a stiffness (K) - damping (C) − Mass (M) model fully characterizes the test article. On the other hand, for operation with an air in oil mixture, the test seal dynamic stiffness coefficients vary greatly with excitation frequency; the direct dynamic stiffness hardens while the cross coupled stiffness decreases as the frequency approaches running speed (ω &lt; Ω) and then increases for super synchronous frequency excitations (ω &gt; Ω). For operation with GVF from 0.1 to 0.8, the wavy seal produces a positive centering dynamic stiffness with large magnitude; a most desirable feature for a vertically installed pump. Notably, the seal direct damping coefficient (C) does not depend on the excitation frequency though reduces continuously as the inlet GVF increases from 0 to 1. For operation with either a pure liquid or a pure air conditions, a computational fluid dynamics (CFD) analysis accurately captures the seal leakage and force coefficients. The current research product adds relevant test data to better the design selection of seals in multiphase pumps.
Effect of Interstage Injection on Compressor Flow Characteristic
Authors: Von Deschwanden Inez , Braun Stefan , Brillert Dieter 
Published: November 2019

Abstract
Wet compression is a widely used approach to enhance the compressor performance of gas turbine units. For wet compression, a water-spray consisting of tiny droplets is injected into the air inlet duct of the compressor. A multi-phase flow of humid air and water droplets enters the compressor. The continued water evaporation inside the compressor stages causes further cooling during the compression process.
Water injection between the compressor stages is called interstage injection. An advantage of interstage injection compared to wet compression is the optimized injection of water at specific positions inside the compressor. The amount of injected water can be adopted to the specific operating conditions of the different injection positions with the ideal of isothermal compression.
Interstage injection can be realized by several techniques. This paper focuses on interstage injection of water from the trailing edge of stator blades. The water spray is generated in the complex wake flow of the airfoil. This leads to strong interaction between the water spray and the carrier gas flow.
In this paper, especially the impact of water injection on the air flow and the spread of the spray is investigated. Phase Doppler Anemometry (PDA) measurements enable two dimensional velocity measurements linked with the droplet size. The comparison of PDA measurements and Computational Fluid Dynamic (CFD) calculations of the dry gas flow allows for the identification of flow instabilities due to interstage injection. Within this publication, a significant influence of the water injection from the trailing edge on the carrier flow is identified. Furthermore, the ability of the spray to spread widely into the flow demonstrates that water injection from the trailing edge is a promising technique for interstage injection.
Validation and Development of DNS Database for Low Prandtl Numbers in Rod Bundle
Authors: Lai Jonathan K. , Merzari Elia , Hassan Yassin A. , Obabko Aleksandr 
Published: November 2019

Abstract
Difficulty in capturing heat transfer characteristics for liquid metals is commonplace because of their low molecular Prandtl number (Pr). Since these fluids have very high thermal diffusivity, the Reynolds analogy is not valid and creates modeling difficulties when assuming a turbulent Prandtl number (Prt) of near unity. Baseline problems have used direct numerical simulations (DNS) for the channel flow and backward facing step to aid in developing a correlation for Prt. More complex physics need to be considered, however, since correlation accuracy is limited. A tight lattice square rod bundle has been chosen for DNS benchmarking because of its presence of flow oscillations and coherent structures even with a relatively simple geometry.
Calculations of the Kolmogorov length and time scales have been made to ensure that the spatial-temporal discretization is sufficient for DNS. In order to validate the results, Hooper and Wood’s 1984 experiment has been modeled with a pitch-to-diameter (P/D) ratio of 1.107. The present work aims at validating first- and second-order statistics for the velocity field, and then analyzing the heat transfer behavior at different molecular Pr. The effects of low Pr flow are presented to demonstrate how the normalized mean and fluctuating heat transfer characteristics vary with different thermal diffusivity. Progress and future work toward creating a full DNS database for liquid metals are discussed.