bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental and Numerical Investigation of Small Particle Erosion in Gas Dominated Multiphase Flow
Authors: Haider G. , Othayq M. , Shirazi S. A. 
Published: October 2021

Abstract
Sand production is a significant challenge in petroleum engineering, and specifically in multiphase gas condensate wells where small amount of liquid is present with the gas. Sand particles entrained in multiphase flow can severely affect the integrity of fluid transportation structures such as pipelines, elbows, and reducers. Traditionally, sand management techniques such as sand screens and gravel packs are used to control sand. However, small particles can pass through these controls. Furthermore, small particles can block a part of the sand screen, causing high velocities in other sections which can cause erosion of the sand screen openings allowing larger particles to pass through which in turn cause more erosion. Furthermore, these small particles are highly susceptible to turbulent regions of flow and can cause severe erosion in these regions. Hence, it is critically important to understand the erosion caused by small particles. This study investigates the effect of small particles on erosion. Small particle erosion is more severe in gas dominated multiphase flows such as annular and mist flows than liquid dominated bubbly and slug flows. A 90-degree standard elbow is used in the experimental and numerical analyses because of its high erosion vulnerability and its importance in pipeline applications. This is because the flow changes direction in this geometry which has complex implications on erosion. This study follows the below mentioned research method:
1) Flow Visualization Study: To understand the flow behavior in bend.
2) Paint-Removal Study: To visualize the progress of paint-removal pattern and to identify the erosion hot spots caused by sand particles.
3) Multiphase Erosion Experiments: To determine the wall thickness loss on identified hot spots using fix-mounted temperature compensated ultrasonic measurement technique.
4) Computational Fluid Dynamics (CFD) Study: To compare erosion patterns with CFD simulations of multiphase flow.
Furthermore, the effects of particle size on erosion ratio and its distribution in pipe bends are discussed. The CFD results of larger particles agree better with experimental data than for smaller particles using existing erosion models.
Low Temperature Testing of Ultrasound Sensors in Liquid Nitrogen
Authors: Chung Joseph Chul , Lee Michael Myung-Sub , Chun Sejong , Yang Inseok 
Published: October 2021

Abstract
Ultrasonic flow metering is one of flow measurement techniques applicable to low temperature environment. Unlike pipe provers or Coriolis mass flowmeters, ultrasonic flowmeters require waveguides in front of ultrasound sensors. The waveguides can prevent heat conduction from the ultrasound sensors to low temperature liquids, such as liquid nitrogen. The ultrasound sensors can maintain its piezoelectricity within the specified temperature ranges by thermal insulation of the waveguides.
In this study, low temperature testing on a pair of ultrasound sensors was performed to see if ultrasound waves could be transmitted normally through liquid nitrogen. A flowmeter cell with diameter of 300 mm (equivalently, 12”) was used as a container for liquid nitrogen. Three pairs of ultrasound sensors were installed in the flowmeter cell. Fiber-optic sensors were also attached on its inner wall to measure the temperature of liquid nitrogen. As a result, ultrasound waves were successfully transmitted between a pair of ultrasound sensors by using a preamplifier. The fiber-optic sensors could measure the temperature of liquid nitrogen although the sensors were not calibrated by the reference temperature scale at KRISS.
Movement of Cell Flowing Over Oblique Micro Grooves in Flow Channel
Authors: Hashimoto Shigehiro , Yonezawa Hiroki 
Published: October 2021

Abstract
A micro flow-channel with bottom-microgrooves has been manufactured by photolithography technique for cell sorting. The movement of each cell passing over microgrooves has been analyzed in relation to cell deformation and alignment in vitro. The flow path (height 0.05 mm × width 1 mm × length 25 mm) between the two transparent PDMS disks has rectangular microgrooves (4.5 μm deep, 0.2 mm long) on the bottom. Variations are made in groove widths (0.03 mm, 0.04 mm, and 0.05 mm). The angle between the flow direction and the longitudinal axis of the groove is 45 degrees. Myoblasts (C2C12: mouse myoblast line) were used in the flow test. The main flow velocity of the medium (0.02 mm/s &lt; vx &lt; 0.23 mm/s) was controlled by the pressure difference between the inlet and the outlet. The shape of each flowing cell was tracked in a movie recorded by a camera attached to the eyepiece of the microscope. Experimental results show that the movement perpendicular to the main flow direction in the micro-groove can distinguish cells in relation to smaller deformations and larger alignment changes.
Frequency Response of Synthetic Jets Emanating From an Array of Circular Orifices
Authors: Arafa Nadim , Sullivan Pierre , Ekmekci Alis 
Published: October 2021

Abstract
The effect of the excitation frequency of synthetic jet actuators on the mean jet velocity of synthetic jets issuing from an array of circular orifices is investigated experimentally. Herein, the focus is placed on an array of circular orifices, rather than a single orifice, as it brings the advantage of covering long-span airfoils. The array consists of 16 circular orifices, each having a diameter of 3.42 mm, distributed over a span of 300 mm. The jets are generated by the excitation of a single cavity via 16 piezoelectric elements. Localized velocity measurements at the exit of the orifices show that the mean jet velocity varies with the excitation frequency. Several distinct resonant peaks were observed in the frequency response. Acoustic simulations of the cavity showed that these peaks correspond to acoustic mode shapes of the cavity. Due to the high-aspect ratio of the cavity, several acoustic mode shapes exist in the excitation frequency range aside from the Helmholtz resonance frequency. Moreover, the mean jet velocity emanating from the array shows a variation from orifice to orifice, depending on the excited acoustic mode.
Different Clogging Behavior of Wastewater Pumps
Authors: Beck David , Holzbauer Yvonne , Thamsen Paul Uwe 
Published: October 2021

Abstract
The transport of wastewater presents operators with increasing challenges for their wastewater pumps due to an increasing proportion of tear-resistant fibrous materials and new types of hygiene articles (e.g. wet wipes) in the wastewater. This paper describes the different clogging behavior of wastewater pumps, which were recorded during the functional performance tests. In addition to the findings of the points susceptible to clogging, the maximum uptake of solids by an impeller is also discussed. The maximum uptake of solids is defined as the degree of saturation. Furthermore, it is shown to what extent the different clogging behavior influence the hydraulic performance and the resulting efficiency changes.
In these tests, it became apparent that wastewater pumps react very differently to clogging. On the one hand, it can lead to a reduction in hydraulic function, which reduces the efficiency of the system. A distinction must be made here as to whether the pumps with a certain number of solids, a defined degree of saturation, retain their function or are brought to a standstill. On the other hand, the hydraulic performance can remain almost constant or, in some cases, be increased despite the clogging that occurs, but this is accompanied by an increased power requirement and can thus reduce the service life and the efficiency of the system.
Visualisation of Interactions Between Impeller and Textile in a Wastewater Pump
Authors: Steffen Matthias , Thamsen Paul Uwe 
Published: October 2021

Abstract
In order to characterize wastewater pumps regarding their clogging behaviour, a wide variety of test procedures with artificial wastewater exist. These tests provide a good insight into the clogging characteristics of a pump. However, conclusions about the clogging mechanisms and their sources cannot be drawn.
This paper deals with the design and implementation of an optical access on the suction side of a wastewater pump to allow visualisation of the interaction between impeller and textile via high-speed recordings. The optical access is realized by an endoscope and a connected high-speed camera with a frame rate of 2000 fps and a resolution of 1024 × 1024 pixels. To ensure sufficient illumination of the impeller, a light ring assembled from 12 high power LEDs with a luminous flux of 5595 lumen are circumferentially arranged around the suction side of the pump. The light ring concept is scalable to fit any pump size. A clogging-affine impeller is developed, 3D printed and used for experimental investigations. For the investigated impeller, the blade’s upper area is identified to be crucial for pump clogging. Optical accessibility provides an important contribution to develop non-clogging impellers.
Vorticity Growth Formed in Vicinity of a Wall on a Moving Elastic Airfoil
Authors: Fuchiwaki Masaki 
Published: October 2021

Abstract
The flow field around moving airfoils capable of flexible elastic deformation has become a focus of attention. These flow fields may be understood as a fluid-structure interaction (FSI) problem, and the motion and deformation of elastic airfoils, as well as the associated vortex flow phenomena in their vicinity, are complicated. Many studies on the flow filed around the elastic moving airfoil have been investigated by experimental and numerical approached. The macro scale vortex structure and the dynamic forces acting on the elastic moving airfoil have been understood. However, the growth process of the vorticity in a vicinity of the wall of an elastic airfoil has not been clarified sufficiently. In this study, the authors focus on the dynamic behaviors of vorticity in the vicinity of the wall on the elastic heaving airfoil and investigate the growth process of the vorticity in a vicinity of the wall of an elastic airfoil by the fluid structure interaction and LES simulations using ANSYS 17.0/ANSYS CFX 17.0. The vorticity in the vicinity of a wall of the elastic airfoil spreads along the wall simultaneously with the increase of the spatial gradient of the wall, and discrete vorticity regions coalesce into a single layer. The time variation in spatial gradient contribute greatly to the growth and development of vorticity.
Boundary Layer Multi-Property Flow Measurements Using a Micro-Plasma Sensor
Authors: Papadopoulos George , Bivolaru Daniel , Martin Nicholas , Dawideit Timothy 
Published: October 2021

Abstract
When voltage is applied between two electrodes situated in close proximity to each other (10–100 μm), a weakly ionized, low temperature plasma discharge can be generated. This in turn creates a plasma sheath, an electrically ionized boundary layer (typically of the order of 10’s to 100’s of microns), where space charge effects dominate. The sheath acts like a virtual capacitor, with the plasma behaving as an inductor. Aerodynamic effects influence the plasma morphology (shape, thickness), thus making the plasma the transduction mechanism. The attraction to the use of plasma discharge as a transduction method for fluid flow property measurement stem from the fact that it lends itself to a probe implementation that is simple in design, can be miniaturized, and at the same time offers unmatched capability for handling ultra-high temperature environments. Sensing plasma discharge characteristics and their variation due to flow interaction can be done electrically, but also optically to yield time-varying intensity and spectral information from fluid-plasma interaction. The current paper focuses on the deployment of a micro-plasma sensor system as a new novel multi-parameter sensing approach for surface flow measurement. Results on pressure dynamics, shear flow, and other possible engineering parameters will be discussed in the context of results from several bench-level experiments.
Second Moment Closure Modeling and DNS of Stratified Shear Layers
Authors: Jain Naman , Huang Xinyi , Yang Xiang , Kunz Robert , Pham Hieu T. , Sarkar Sutanu 
Published: October 2021

Abstract
Buoyant shear layers are encountered in many engineering and environmental applications, and have been studied by researchers in the context of experiments and modeling for decades. Often, these flows have high Reynolds and Richardson numbers, and this leads to significant/intractable space-time resolution requirements for DNS or LES modeling. On the other hand, many of the important physical mechanisms in these systems, such as stress anisotropy, wake stabilization, and regime transition, inherently render eddy viscosity-based RANS modeling inappropriate. Accordingly, we pursue second-moment closure (SMC), i.e., full Reynolds stress/flux/variance modeling, for moderate Reynolds number non-stratified, and stratified shear layers for which DNS is possible. A range of sub-model complexity is pursued for the diffusion of stresses, density fluxes and variance, pressure strain and scrambling, and dissipation. These sub-models are evaluated in terms of how well they are represented by DNS in comparison to the exact Reynolds averaged terms, and how well they impact the accuracy of the full RANS closure.
For the non-stratified case, the SMC model predicts the shear layer growth rate and Reynolds shear stress profiles accurately. Stress anisotropy and budgets are captured only qualitatively. Comparing DNS of exact and modeled terms, inconsistencies in model performance and assumptions are observed, including inaccurate prediction of individual statistics, non-negligible pressure diffusion, and dissipation anisotropy. For the stratified case, shear layer and gradient Richardson number growth rates, and stress, flux and variance decay rates, are captured with less accuracy than corresponding flow parameters in the non-stratified case. These studies lead to several recommendations for model improvement.
Simple, Cost-Effective Fabrication, and Flow Dynamics Analysis of a Passive Microfluidic Mixer Using 3D Printing and Soft Lithography
Authors: Rubby Md Fazlay , Parvez Mohammad Salman , Islam Nazmul 
Published: October 2021

Abstract
Simple and low-cost fabrication of microfluidic devices has attracted considerable attention among researchers. The traditional soft lithography fabrication method requires expensive equipment like a UV exposure system and mask fabrication facility. In this work, an alternative and low-cost UV exposure system was introduced along with an alternative mask fabrication system. A previously reported passive microfluidic mixer was fabricated successfully using this modified soft lithography method. Challenges were presented during this modified fabrication method. Another emerging potential alternative for the fabrication of microfluidic mixers is 3D printing. It was also used in this experiment to fabricate a passive micromixer. This method is well known for rapid prototyping and the creations of complex structures. However, this method has several disadvantages like optical transparency, lower resolution fabrication, difficulties in flow characterization, etc. These problems were addressed, and the solutions were discussed in this work. Comparative analysis between 3D printing and soft lithography fabrication was presented. Flow characterization inside the 3D printed micromixer was carried out using the microparticulate image velocimetry (micro-PIV) system. It explains how the geometrical shape of the micromixer accelerates the natural diffusion process to mix the different fluid streams. Finally, a 3D numerical simulation of the passive micromixer was carried out to visualize the flow dynamics inside the micromixer. The flow pattern found from the numerical simulation and the experimental flow characterization is analogous. These observations could play an important role to design and fabricate cost-effective micromixers for lab-on-a-chip devices.
Fluid-Structure Interaction Simulations of Parachute Deployment and Inflation
Authors: Wang Liwu , Tang Mingzhang , Liu Yu , Zhang Sijun 
Published: October 2021

Abstract
The numerical simulation of the parachute deployment/inflation process involves fluid structure interaction problems, the inherent complexities in the fluid structure interaction have been posing several computational challenges. In this paper a high fidelity Eulerian computational approach is proposed for the simulation of parachute deployment/inflation. Unlike the arbitrary Eulerian Lagrangian (ALE) method widely employed in this area, the Eulerian computational approach is established on three computational techniques: computational fluid dynamics, computational structure dynamics and computational moving boundary. A set of stationary, non-deforming Cartesian grids is adopted in our computational fluid dynamics, our computational structure dynamics is enhanced by non-linear finite element method and membrane wrinkling algorithm, instead of conventional computational mesh dynamics, an immersed boundary method is employed to avoid insurmountable poor grid quality brought in by moving mesh approaches. To validate the proposed numerical approach the deployment/inflation of C-9 parachute is simulated using our approach and the results show similar characteristics compared with experimental results and previous literature. The computed results have demonstrated the proposed method to be a useful tool for analyzing dynamic parachute deployment and subsequent inflation.
Shape Optimisation of NACA4412 In-Ground Effect- Selection of a Turbulence Model
Authors: P. N. Jithin , Arumugham-Achari Ajith Kumar 
Published: October 2021

Abstract
Shape optimisation of a wing-in-ground airfoil would be required to improve its aerodynamic characteristics under various flight conditions. Identification of an optimised shape at various heights above ground (h/c) and angles of attack (α) could be helpful in developing morphing wing capabilities for such airfoil. Prior to conducting shape optimisation a suitable turbulence model have to be selected for such studies. We have performed In-ground-effect (IGE) simulations using four turbulence models, viz., Spalart Allmaras, SST k-ω, Standard k-ε and Transition SST model, to compare their advantages and disadvantages during such analysis. For an unaltered NACA4412 airfoil, while all the models predicted coefficient of lift (Cl) in close agreement with experimental results, Transition SST model was able to predict fine details like laminar separation bubble formation. There was a generic discrepancy in predicting drag coefficients (Cd) with all these turbulence models. However results from Transition SST were the closest to experiments. Spalart Allmaras and SST k-ω were better in the prediction of Cd when compared to standard k-ε model. We consider such studies would be helpful to generate a database of optimised airfoils for a variety of flight conditions near to ground.
Solution-Responsive Particle Size Adaptivity in Lagrangian Vortex Particle Methods
Authors: Stock Mark J. , Gharakhani Adrin 
Published: October 2021

Abstract
In order to minimize the computational resources necessary for a given level of accuracy in a Lagrangian Vortex Particle Method, a novel particle core size adaptivity scheme has been created. The method adapts locally to the solution while preventing large particle size gradients, and optionally adapts globally to focus effort on important regions. It is implemented in the diffusion solver, which uses the Vorticity Redistribution Method, by allowing and accounting for variations in the core radius of participating particles. We demonstrate the effectiveness of this new method on the diffusion of a δ-function and impulsively started flow over a circular cylinder at Re = 9,500. In each case, the adaptive method provides solutions with marginal loss of accuracy but with substantially fewer computational elements.
Elementary Numerical Analysis of Wet Foam Formation and Study of Its Flow Structures and Physical Behavior
Authors: Shirani Ebrahim , Nasirzade Sima , Aloui Fethi 
Published: October 2021

Abstract
The purpose of this study is to analyze the flow of wet foam and to study the effect of volume fraction, velocity and surface tension and other physical parameters on the foam flow. The most numerical researches done in this area are for single-phase flows. The numerical simulation in this study is the first simulation in the foam flow, in which both the bubbles and the water are simulated as two-phase flow. In this study, fluid containing a surfactant and bubbles are flowing in a duct. The dimensions of the duct cross section is 15 × 60 in millimeters. The numerical solution is performed for three Reynolds numbers of 50, 100 and 1000, three volume fractions of 48, 41 and 28, and three Weber numbers of 0.405, 0.27 and 0.203 (27 different modes), and the effect of the above parameters on the flow behavior and its physical properties have been investigated.
It was found that in foam flow, the velocity fluctuations, due to the movement of bubbles in the flow, is in the order of magnitude of the mean velocity. The same is true for wall shear stress. By increasing the Reynolds number, the pressure loss increases, the magnitude of the velocity fluctuations decreases and the frequency of the velocity fluctuations increases. By increasing the Weber number, the pressure loss and the magnitude of the velocity fluctuations decrease and the mean shear stress increases. By increasing the foam quality, pressure loss increases, the mean shear stress and the magnitude of the velocity fluctuations decrease and its frequency increases. And the phenomenon of coalescence causes a sudden increase in momentum speed.
A Hybrid High-Order Vorticity-Based Eulerian and Lagrangian Vortex Particle Method, the 2-D Case
Authors: Stock Mark J. , Gharakhani Adrin 
Published: October 2021

Abstract
Hybrid Lagrangian-Eulerian solvers combine the convective and compactness advantages of vortex methods with the spatial anisotropy and boundary-resolving advantages of Eulerian methods to create flexible solvers capable of adequately capturing thin boundary layers while still maintaining wake vortex coherency for unsteady incompressible flow in complex geometries. The present paper details a new hybrid method which combines, in one open-source package, a novel, compact, high-order Eulerian scheme for vorticity transport to predict the flow in the near-boundary region with a grid-free, unremeshed, Lagrangian Vortex Particle Method (LVPM) for the off-boundary vorticity-containing region. This paper focuses on the hybridization of the two methods and demonstrates its effectiveness on two canonical benchmarks: flow in 2-D lid-driven cavity at Re = 1,000 and impulsively started flow over a circular cylinder at Re = 9,500. In each case, the hybrid method improves upon a pure LVPM and uses far fewer cells than a purely Eulerian scheme. In addition, the size of the associated Eulerian region is greatly reduced compared to previous hybrid methods.