bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Improved Level-Set-Based Immersed Boundary Reconstruction Method for Computing Bio-Inspired Underwater Propulsion
Authors: Pan Yu , Dong Haibo , Zhang Wei 
Published: October 2021

Abstract
The immersed boundary method (IBM) has been widely employed to study bio-inspired underwater propulsion which often involves the high Reynolds number, complex body morphologies and large computational domain. Due to these problems, the immersed boundary (IB) reconstruction can be very costly in a simulation. Based on our previous work, an improved level-set-based immersed boundary method (LS-IBM) has been developed in this paper by introducing the narrow-band technique. Comparing with the previous LS-IBM, the narrowband level-set-based immersed boundary method (NBLS-IBM) is only required to propagate the level set values from the points near the boundaries to all the points in the narrow band. This improvement reduces the computational cost from O((LD/Δx)3) to O(k(LD/Δx)2). By simulating a steady-swimming Jackfish-like body, the consistency and stability of the new reconstruction method in the flow solver have been verified. Applications to a dolphin-like body swimming and a shark-like body swimming are used to demonstrate the efficiency and accuracy of the NBLS-IBM. The time for reconstructions shows that the reconstruction efficiency can increase up to 64.6% by using the NBLS-IBM while keeping the accuracy and robustness of the original LS-IBM. The vortex wake of the shark-like body in steady swimming shows the robustness, fastness and compatibility of the NBLS-IBM to our current flow solver.
The Effect of Membrane Topology on Separation Performance of Vacuum Membrane Distillation Module
Authors: Caspar Justin , Xue Guanyang , Krysko Robert , Oztekin Alparslan 
Published: October 2021

Abstract
Computational fluid dynamics simulations were conducted to evaluate the effect of a wavy channel in a two-dimensional vacuum membrane distillation module. The curvature was induced using a sinusoidal profile along the membrane and bottom wall. Contour plots and line profiles provide a detailed view of the flow structure and the effect of the proposed configuration on the flux performance. Module averaged temperatures, concentrations, and flux values were calculated for two selected Reynolds numbers. Results indicate that at low Reynolds numbers, the wiggly module performs worse than the flat sheet module. Due to the channel’s curvature changing the direction of the bulk flow and the absence of secondary flows to promote mixing, the thermal boundary layer along the membrane surface can be more intense versus a flat sheet membrane, causing more intense temperature polarization and reduced flux performance. At Reynolds number 500, there was a 5% decrease in the flux for the curved versus flat case. However, in some curved channel areas, the local performance was superior to the flat channel. Increasing the Reynolds number could aid the performance of the wiggly channel immensely.
Digital Assignments for Thermo-Fluids Courses
Authors: Milanovic Ivana , Eppes Tom A. , Goparaju Kalyan 
Published: October 2021

Abstract
Simulations were used in lecture-based courses, Thermodynamics I and Thermodynamics II, for demonstration purposes and as digital assignments. Digital assignments were separate from the customary pencil & paper homework given once a week. The primary objective was to model the flow and heat transfer in a system, reinforce theoretical concepts, and allow study of more complex two- and three-dimensional problems.
Students encounter fluid flow and heat transfer in the sophomore course, Thermodynamics I, for the first time. Velocity, pressure and temperature fields are quite complicated even for simple geometries, hard to visualize, and difficult to understand. Digital assignments go beyond basic theoretical concepts and relatively simple pencil & paper problems. Initially, there were 6 digital assignments in each course. After the first offerings and assessments, the number of assignments is expected to grow to 8–10. Scaffolding of digital assignments ensured that simulations gain in complexity as students become more familiar with both the theoretical underpinnings and the software interface.
Our Mechanical Engineering program, has a freshmen graphic communication course incorporating AutoCAD and a junior CAD course with SolidWorks and Ansys. This provided both a challenge and an opportunity for lecture-based thermo-fluids courses positioned ‘in between.’ Modern computational skills were obtained outside the classroom, and that was accomplished with effective use of an on-line environment. Ansys Fluent was chosen to present and reinforce thermo-fluids fundamentals. Each digital assignment had a mesh, detailed grading criteria, and supplementary documentation. Students worked on the: (1) problem set up in the preprocessor-stage, (2) solver, and (3) postprocessor. This approach helped students (1) understand the flow and heat transfer inside the system as well as the application of conservation of mass and energy, (2) understand and interpret results by comparing them with theoretical and experimental data, (3) develop modern technical skills relevant to the demands of Industry 4.0, and (4) develop research capabilities.
Simulations in the classroom and as digital assignments are a representation of the real world, and provide an egalitarian and unrestricted way for students to interact with it, acquiring skills and an appreciation for subject matter as well as the engineering profession. Semester long discussions on various aspects of digital assignments help develop a mentor-mentee bond. This approach to teaching, research and mentoring does not depend on access to laboratory facilities and funding that can reach only a limited number of students. It encourages students’ spirit of inquiry, and ultimately leads to a professional development opportunities beyond the classroom setting.
Hysteresis Effect of Tangential Force Field With Centrifuge on Myoblast: Cultured on Striped Pattern of Micro Ridge for Direction Control
Authors: Hashimoto Shigehiro 
Published: October 2021

Abstract
Hysteresis effects of the direction of mechanical stimulation on the cell behavior have been examined in vitro. A micro ridge pattern was made on the surface of the scaffold to align the directions of the cells being stimulated. The stripe pattern (0.7 μm heigh, 3 μm wide, and 3 μm interval) was created by the photolithography technique. Three regions, which have the uniform value of the angle between the longitudinal direction of the ridge and the direction of the tangential force, were set: 0, 45, and 90 degrees in each region. Myoblasts (C2C12: mouse myoblast cell line) were used in the experiment. The scaffold plate with cells was set in the tube of a conventional centrifuge placed in an incubator to apply the tangential force field to each cell. After the cell culture for 5 hours with centrifugation, the behavior of each cell was analyzed on time-lapse microscopic images for 10 hours. Experimental results show that cell activities (migration and deformation) are enhanced after stimulation of tangential forces perpendicular to the long axis of myoblasts.
A Unified Theory for the Pressure Change of Sudden Expansions and Contractions Based on the Momentum Balance
Authors: Müller Sebastian , Malcherek Andreas 
Published: October 2021

Abstract
In this paper a unified approach based on the momentum balance is presented, capable of predicting the pressure change of sudden contractions and sudden expansions. The use of empirically determined correction coefficients is not necessary. Therefore, the momentum balance is derived similarly for both applications but with different control volumes. The control volume takes into account the specific geometry of the hydraulic structure. With a properly chosen control volume, the unified approach requires coefficients that account for the velocity as well as pressure distributions on the boundaries of the control volume. These coefficients can be obtained by parameterizing the results of numerical simulations by simple analytical functions. The numerical model itself is validated by checking the simulated pressure change against calculated or measured pressure changes. It is found that the formulation of the momentum balance for the sudden expansion is more complex compared with the sudden contraction. The prediction of the pressure change of flows through sudden expansions can be improved by applying the momentum balance non-idealized. Most of the correction coefficients originate from an inappropriate application of Bernoulli’s energy conservation principle. Consequently, this leads to a gap between theory and experimental results. The proposed unified approach solely contains physical coefficients that are used to substitute integrals by averaged expressions.
Large Eddy Simulations of a Turbocharger Radial Turbine Under Pulsating Flow Conditions
Authors: Mosca Roberto , Lim Shyang Maw , Mihaescu Mihai 
Published: October 2021

Abstract
The pulsating flow conditions which a turbocharger turbine is exposed cause important deviations of the turbine aerodynamic performance when compared to steady flow conditions. Indeed, the secondary flows developing in the turbine are determined by the inflow aerodynamic conditions, which largely vary during the pulse cycle.
In this paper, a high-resolved Large Eddy Simulation is performed to investigate and characterize the flow field evolution in a turbocharger radial turbine over the pulse cycle. At first, the model is validated against experimental results obtained in gas-stand flow conditions. Then, the instantaneous flow field at the rotor mid-span section is compared to the one given by the equivalent cycle-averaged steady flow conditions. The results highlight five distinct flow features. At low mass flow rates, when the relative inflow angle assumes large negative values, the flow separates at the blade pressure side, causing a secondary flow consisting in two counter-rotating vortices characterized by a diameter comparable to the blade passage. As the mass flow rate increases, the first vortex persists at the blade tip while the second one moves closer to the blade trailing edge. This corresponds to the second characteristic flow field. With increasing relative inflow angle, for the third characteristic flow feature, only the recirculation at the blade leading edge is displayed and its size gradually reduces. For the fourth characteristic flow feature, at moderate negative values of the relative inflow angle, the flow field is well aligned with the blade profile and free of secondary flows. Then, as the relative inflow angle gradually grows towards large positive values, the flow separates on the blade suction side causing the mixing of the flow with the stream flowing on the pressure side of the previous blade.
Influence of Exposed Electrode Thickness on Plasma Actuators Performance for Coupled Deicing and Flow Control Applications
Authors: Rodrigues F. F. , Abdollahzadeh M. , Pascoa J. , Pires L. 
Published: October 2021

Abstract
Dielectric Barrier Discharge (DBD) plasma actuators are a popular topic of research within the active flow control field. Recently, these devices have gained interest for deicing and ice prevention applications and it has been proved they allow to perform simultaneously deicing and flow control. Studies have shown that the exposed electrode plays an important role on the surface temperature field of the plasma actuator. Thus, in the current study, by the first time, we investigate the influence of the exposed electrode thickness on the induced velocity flow field and surface temperature field. Three plasma actuators with different dielectric thicknesses (0.3 mm, 0.6 mm and 1.02 mm) were mounted with a thick exposed electrode (thickness of 0.8 mm). These three actuators with thick exposed electrode were experimentally studied and compared against other three plasma actuators with same dielectric thickness but with a thin exposed electrode (thickness of 80 μm). The DBD actuators were experimentally studied considering their electrical, mechanical and thermal behavior. The results are presented and discussed in order to understand the influence of the exposed electrode thickness on the mechanical and thermal plasma actuator performances.
Analysis and Implementation of Dielectric Barrier Discharge Plasma Actuators for Ground Vehicles Wake Reduction
Authors: Rodrigues F. F. , Moreira M. , Pascoa J. 
Published: October 2021

Abstract
Plasma actuators are promising devices with several possible applications in active flow control field. One of the possible applications of these devices is wake reduction in ground vehicles. By delaying the flow separation and reducing the wake of the flow, these devices allow to reduce the drag which, in turns, leads to important savings in terms of fuel consumption. In the current work, the operation of dielectric barrier discharge plasma actuators is studied considering their application for active flow control in ground vehicles. A plasma actuator was fabricated and experimentally characterized in terms of electrical and mechanical features. A ground vehicle model, with different rear slant angles, was constructed and preliminary tests were performed in a wind tunnel. The dielectric barrier discharge plasma actuator was implemented on the top rear part of the model, in the first separation zone of the flow, in order to attach the flow to the surface and reduce the wake flow. The experimental tests were performed for rear slant angles of 30°, 45° and 60°. The different vehicle models were tested for a flow velocity of 5m/s. Flow visualization and velocity measurements were performed in order to analyze the flow behavior and the active flow control effect obtained by the plasma actuation. It is shown that by using plasma actuators on the rear of the model, the plasma actuation pulls the flow toward the surface and reduce the wake of the flow.
A Novel Mathematical Framework for the Venous Valve Leaflet Morphology Extracted From In-Vitro Images Using Machine Learning Assisted Stereological Analysis
Authors: Kotteda V. M. Krushnarao , Janssen Herb F. , Harris Christopher , Kumar Vinod 
Published: October 2021

Abstract
It has been suggested that stasis (stagnant zones over a period of time, dependent on other factors such as age, or underlying medical conditions, such as cancer or covid19) in the valve pockets may increase the risk of clots due to stasis in combination with other factors increases the risk of Deep Venous Thrombosis (DVT) formation, blood stasis may also result in a decrease in the anticoagulants factors that prevent clots from forming, and if the vein wall is damaged this further increases the risk of clot formation. We propose a proactive framework to predict DVT vulnerability, track progression and provide patient care checkpoints is of clear benefit. The framework is based on leading-edge cloud computing technologies and promises to offer user-friendly Software- & Platform-as-a-Service (SaaS/PaaS) solutions via novel machine learning (ML) algorithm and high fidelity blood flow modeling through the venous network under various valve configurations. In this work, we will present the progress made towards the leaflet morphology extraction from in-vitro images using ML assisted stereological analysis for obtaining a sufficiently accurate representation of morphology. Ultimately, the workflow can be tailored to specific patients. The extracted valve is used to identify red-flag stagnant zones by a detailed, physics-based computational study of the blood flow through the leaflet models.
A Microfluidic Platform for On-Chip Analysis of Circulating Tumor Cells
Authors: Darabi Jeff , Schober Joseph 
Published: October 2021

Abstract
Studies have shown that primary tumor sites begin shedding cancerous cells into peripheral blood at early stages of cancer, and the presence and frequency of circulating tumor cells (CTCs) in blood is directly proportional to disease progression. The challenge is that the concentration of the CTCs in peripheral blood may be extremely low. In the past few years, several microfluidic-based concepts have been investigated to isolate CTCs from whole blood. However, these devices are generally hampered by complex fabrication processes and very low volumetric throughputs, which may not be practical for rapid clinical applications. This paper presents a high-performance yet simple magnetophoretic microfluidic chip for the enrichment and on-chip analysis of rare CTCs from blood. Microscopic and flow cytometric assays developed for selection of cancer cell lines, selection of monoclonal antibodies, and optimization of bead coupling are discussed. Additionally, on-chip characterization of rare cancer cells using high resolution immunofluorescence microscopy and modeling results for prediction of CTC capture length are presented. The device has the ability to interface directly with on-chip pre and post processing modules such as mixing, incubation, and automated image analysis systems. These features will enable us to isolate rare cancer cells from whole blood and detect them on the chip with subcellular resolution.
Performing Fourier Transform on a Velocity Profile From Atmospheric Turbulence Studies
Authors: Adansi Richard , Terrazas Jose , Rodriguez Arturo , Kotteda V. M. Krushnarao , Kumar Vinod , Rubio Aldo , Avalos Edgar 
Published: October 2021

Abstract
Atmospheric Turbulence poses a challenge to land-based observatories operated by the United States Air Force (USAF) tasked with space situational awareness. By developing new methods for quantifying Turbulence, we intend to provide increased USAF capability in this domain. Current models for quantifying atmospheric Turbulence include Kolmogorov and Non-Kolmogorov methods. Through the nature of Fourier Transform, sinusoidal function, it is possible to determine the frequency at which velocities occur in a specified vertical distance and eventually determine eddy size in a control volume. First, an ANSYS Computational Fluid Dynamics (CFD) model will be created to simulate atmospheric Turbulence in a defined control volume. The simulation will include a one-dimensional flow over a flat plate. The data we acquired from the simulation were used to derive an equation relating the velocity to the vertical distance (velocity profile). We will perform a regression analysis to fit data from Large-Eddy Simulations (LES) and apply Fourier transformation from a time domain to a frequency domain. The objective is to use Fourier transform analysis to determine eddy size distribution and turbulent cascade dissipation in a control volume by analyzing the frequency of velocities. By calculating such eddy size distribution, we may quantify Turbulence in said control volume and compare results with the traditional Kolmogorov method.
Investigation of Proppant Distributions in Rock Fractures With Applications to Hydraulic Fracturing
Authors: Mofakham Amir A. , Rousta Farid , Crandall Dustin M. , Ahmadi Goodarz 
Published: October 2021

Abstract
Hydraulic fracturing or fracking is a procedure used extensively by oil and gas companies to extract natural gas or petroleum from unconventional sources. During this process, a pressurized liquid is injected into wellbores to generate fractures in rock formations to create more permeable pathways in low permeability rocks that hold the oil. To keep the rock fractures open after removing the high pressure, proppant, which typically are sands with different shapes and sizes, are injected simultaneously with the fracking fluid to spread them throughout rock fractures. The extraction productivity from shale reservoirs is significantly affected by the performance and quality of the proppant injection process. Since these processes occur under the ground and in the rock fractures, using experimental investigations to examine the process is challenging, if not impossible. Therefore, employing numerical tools for analyzing the process could provide significant insights leading to the fracking process improvement. Accordingly, in this investigation, a 4-way coupled Computational Fluid Dynamic and Discrete Element Method (CFD-DEM) code was used to simulate proppant transport into a numerically generated realistic rock fracture geometry. The simulations were carried out for a sufficiently long period to reach the fractures’ steady coverage by proppant. The proppant fracture coverage is a distinguishing factor that can be used to assess the proppant injection process quality. A series of simulations with different proppant sizes as well as various fracking fluid flow rates, were performed. The corresponding estimated fracture coverages for different cases were compared. The importance of proppant size as well as the fluid flow rate on the efficiency of the proppant injection process, were evaluated and discussed.
Dispersion of Particles Coming Out of the Mouth While Speaking in a Ventilated Indoor Environment
Authors: Ali Masoomi Morteza , Salmanzadeh Mazyar , Ahmadi Goodarz 
Published: October 2021

Abstract
Breathing air that contains virus-infected droplets is the leading cause of Covid-19 transmission. Sneezing, coughing, breathing, and talking of an infected person would generate aerosolized droplets that carry the coronavirus. Earlier research efforts have focused on sneezing and coughing as the primary transmission sources. New experiments and field studies have shown that breathing and talking are also effective mechanisms in spreading viruses. In this article, the dispersion of particles/droplets during speaking is studied. COVID-19 virus is about 120 nanometers and is suspended in saliva or mucus droplets emitted by an injected person. These droplets evaporate in a fraction of a second as they enter the environment and reduce in size. However, the droplets’ viral content remains the same as they move by the room’s airflow. The particles from sneezing and coughing are larger than those released by speaking. As the particles/droplets are small, the effect of gravity is small, and they remain suspended in the air for a long time. Also, being small makes them more easily penetrate the respiratory passages.
Using the computational fluid dynamics method in conjunction with the ANSYS-Fluent software, the particle transport and dispersion were simulated. The Eulerian approach modeled the airflow (continuous phase), and the Lagrangian approach modeled the particle (discrete phase) movements. This study also investigated the ventilation system’s effects on the distribution of particles in the indoor environment. The displacement and mixing air distribution systems were considered. Simulation results showed that droplets remain suspended in the room for a relatively long time after evaporation. Large particles were deposited quickly, and a significant percentage of smaller particles were removed by the ventilation system. The concentration of particles in the upper half of the room was also quite low for the mixing ventilation system. This was due to the fact that the room air mixing system is relatively uniform; this uniformity of airflow caused the particles to get trapped quickly. Also, for the displacement system, the room airflow was not uniform; these particles were then dispersed in the room and spent more time in the indoor environment.