bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical Properties of Irreversible Gel Induced by Dosing With Surfactant Solution
Authors: Hirota Shin , Hara Shumpei 
Published: September 2022

Abstract
In the present study, the conditions related to the irreversible physical gel formation of cm size are quantitatively investigated by applying shear and extensional deformation to the surfactant solution by dosing through meshes, together with image analysis based on observation results. Dynamic viscoelasticity measurements were performed using a rheometer to clarify the rheological properties of the FIS gels, and relaxation times were also calculated using the Maxwell model.
From the observation results, it was confirmed that the solution sank in a lumpy state in four out of twelve conditions. The solution remained lumpy for up to fifteen minutes, indicating that it was an irreversible physical gel. Furthermore, the results of image analysis by luminance values of the observation movies over time provided high luminance values for the condition of the gel formation. The dynamic viscoelasticity measurement showed solid-like properties in a wider frequency band of the condition of the gel formation. Moreover, the relaxation time was 4.5–11.8 s. From the observation, dynamic viscoelasticity measurement, and relaxation time, the dosed fluid with an irreversible gel showed solid-like properties for a long time.
Effects of an Impingement Plate Upon the Turbulent Velocity of a Two Parallel Plane Jet With a Periodic Vortex Shedding Phenomenon
Authors: Hiromasa Soichiro , Hara Shumpei , Inaoka Kyoji 
Published: September 2022

Abstract
In impinging jets, vortices from incoming jets play a key factor in enhancing heat transfer. One mechanism to produce vortices is a two parallel plane jet, reported to have a periodic vortex shedding at certain jet spacing ratios and increase turbulent mixing. In this study, particle image velocimetry (PIV) measurements were done for a two parallel plane free jet with a vortex shedding phenomenon and a two parallel plane impinging jet with the same exit conditions. Turbulence statistics were focused upon to determine the effects created by the impingement plate upon a two parallel plane jet. Both cases showed a periodic vortex shedding phenomenon, but the impinging jet showed a smaller vortex shedding frequency, due to the pressure gradient caused by the impingement plate. Average velocities showed similar tendencies in the free jet region. However, once past 50% of the impingement height, differences emerged both in average velocity and turbulent statistics signifying the beginning of the impingement region. Due to a constant transverse flow, time-varying components were minimal in the impingement region, causing turbulence statistics to become smaller in the region. It can be said that the impingement plate does not prevent the vortex shedding phenomenon at the set impingement height, but causes turbulence statistics in downstream regions to decline for a two parallel plane impinging jet.
Usage of Clear Water Pumps in Wastewater Treatment Plants – Field Study
Authors: Holzbauer Yvonne , Thamsen Paul-Uwe 
Published: September 2022

Abstract
Pumps in wastewater treatment plant (WWTP) applications are typically equipped with sewage hydraulics (f.e. vortex, single or double channel impellers). Those impellers have a clogging preventing shape with large ball passing diameters, low blade numbers and depending on the impeller style, also special features (e.g. cutting functions). This clogging preventing shape has an influence on the resulting pump efficiency, which is in general lower than from clear water pumps.
This difference is caused by a closer gap design and the increased number of blades for clear water pumps. There are sewage applications, where those special impellers are not needed, but made by history, preferred.
However, in a WWTP the already screened wastewater doesn’t need special wastewater hydraulics. During the treatment process, organical and anorganical substances are removed from the wastewater. One of those sub-streams contains the removed organical load, like toilet paper and feces, which is mainly used in digesters for the degradation of the organic matter to methane gas.
Especially for the wastewater in this treatment step, a clear water pump is selected, which has a much better efficiency compared to the existing vortex pump.
By doing a field test in a sewage plant (&gt; 500.000 population equivalent) the challenges from this organical loaded media and the effect on a clear water, open three-vane impeller are described. Different modifications of the three-vane impeller are made to still have the advantages of a high efficiency hydraulic in combination with an operational safety.
The right sampling as well as the description of the media pumped are very important for the hydraulic selection. Due to the different modifications, challenges, e.g. the trapping of hair in the impeller entrance, were able to overcome to achieve an efficiency advantage for the new selected open three-vane impeller compared to the previous vortex impeller.
Flow Simulation and Investigation Around a Estate Vehicle Using Hybrid Methods
Authors: Delassaux Francois , Mortazavi Iraj , Herbert Vincent , Ribes Charles 
Published: September 2022

Abstract
In this work hybrid RANS/LES methods are adapted in order to simulate the flow around a realistic car geometry (estate vehicle). Numerical results are compared to in-house experiments. In order to achieve an accurate understanding of the flow behavior around the car geometry, a wide range of experiments are performed measuring forces, pressure coefficients and tomography for 3D description of the flow in the wake of the body.
Vortex Structure Generated by a Sweeping Jet in a Cross Flow and its Creation Process
Authors: Fuchiwaki Masaki , Raghu Surya 
Published: September 2022

Abstract
A sweeping jet produced by a fluidic oscillator has recently been examined from the viewpoint of flow separation control. Studies have proposed active flow control techniques for an airfoil based on sweeping jets. Most of these studies focused on the characteristics of the dynamic forces acting on the airfoil. However, the flow fields formed by the interaction between the sweeping jet and the main flow and their flow mechanisms are poorly understood. In particular, the vortex structure and flow mechanism formed by the interaction with respect to the velocity ratio between the sweeping jet and the main flow and the growth mechanisms of the vortex structure formed by the interaction have not been clarified. The detailed vortex structure generated by the interaction between the sweeping jet and the main flow was quantitatively examined using stereo PIV. The stream tube generated by the interaction between the sweeping jet and the main flow consists of two vortex tubes near the outlet of the sweeping jet at a location of 1.0d to 11.3d. At locations of 22.5d and 30.0d, a pair of vortex tubes gradually separates. Each vortex tube develops in the wake and its vorticity weakens.
Geometric Analysis of Insect Wing Vein Network
Authors: White Jacob , Hu Ying , Ryu Sangjin , Kim Seunghee , Zhang Haipeng 
Published: September 2022

Abstract
An insect wing consists of a thin membrane supported by a system of veins, and flow of blood through the system of veins is critical for maintaining healthy insect wings. Better understanding of the insect wing vein circulation requires to know how the efficiency of blood flow in an insect wing relates to the geometric shape of the vein. Our investigation of the wing vein network of a dragonfly Anax junius follows the idea of Murray’s law, which is established in the study of efficiency of the vein network and the geometric shape of the vein. Instead of using the classic Murray’s law for circular cross-sections, we derived a variation of the Murray’s law for vein cross-sections of equilateral triangles. Then, we evaluated the conformity of the studied wing vein network to Murray’s law by measuring the diameter of veins of the forewing of A. junius. Our data suggest that the vein network does not abide by the class Murray’s law and support that the shape of the vein is not cylindrical.
LES Investigation of Pollution Dispersion in a Street Canyon
Authors: Boontanom Jedhathai (Vicky) , Tafti Danesh 
Published: September 2022

Abstract
This study focuses on predicting the pollution dispersion in a street canyon using Large-Eddy Simulations (LES). The predictions are compared to wind tunnel experiments done at Karlsruhe Institute of Technology (KIT), Germany. The geometry consists of a long canyon with width-to-height, W/H = 1, placed in a turbulent boundary layer flow perpendicular to the length of the canyon. Pollutant (SF6 in the experiments) is injected in the canyon at street level through a series of flush-mounted equidistant hypodermic 0.4 mm diameter tubes acting as two line sources near the leading and trailing side of the canyon to simulate vehicular exhaust. A multi-species, variable property LES is conducted in a domain 41H × 8H × H/190 by using periodic boundary conditions along the length of the canyon on a grid of 1.6 million cells. The predicted mean concentration of pollutant is compared to experimental measurements at two locations within the canyon. The two are in satisfactory agreement considering that only a small fraction of the canyon length is modeled. A greater deviation in concentration prediction is found closer to the ground level, implying less dispersion of the pollutant. The over-prediction has also been observed in other LES investigations. The rms concentration fluctuations are much larger in comparison to previous LES on the full canyon length. This is attributed to the large-scale coherence of turbulent structures resulting from the absence of any three-dimensional long wavelength instabilities developing in the lateral direction.
Numerical Investigation of Flow and Thermal Behavior in Channels With PCM-Filled Thermal Energy Storage Columns for Potential Application in Photobioreactors
Authors: Akber Sameed , Siddiqui Kamran , DeGroot Christopher 
Published: September 2022

Abstract
Microalgae has been identified as a potential source in the production of biofuel. Photobioreactors, which are used for microalgae production, normally experience temperature variations over the diurnal cycle due to changes in ambient conditions. Such temperature variations affect microalgae growth since microalgae are sensitive to these temperature variations. Hence, the thermal regulation of photobioreactors to minimize temperature variations will result in higher yield of microalgae. The present research is aimed to investigate an innovative approach to thermally regulate photobioreactors by introducing passive thermal energy storage using phase change materials (PCM) where the latent heat of the material is exploited as the energy storage. The present research uses a numerical approach to study the flow and thermal behaviors in a channel with a set of wall-confined, offset thermal storage columns. The research aims to investigate the melting behavior of the PCM inside these storage columns and the transient thermal response of the channel flow.
Open source CFD software, OpenFOAM, is used to numerically simulate flow in a rectangular channel containing offset PCM columns. The model is validated against experimental data. A parametric analysis is performed to investigate the impact of various operating and geometric properties on the heat transfer to the PCM columns, with the aim to optimize the channel geometry to maximize the heat exchange between the PCM columns and the channel fluid.
Effect of the Rear Geometry on the Flow Structure and Drag of the Ahmed Body
Authors: Harley Trevor , Siddiqui Naseeb Ahmed , Agelin-Chaab Martin 
Published: September 2022

Abstract
There is a need for fuel-efficient vehicles to reduce greenhouse emission and minimize the range problem of electric vehicles. Aerodynamic drag reduction provides one of the cheapest but effective alternatives. Therefore, the development and analysis of new passive strategies that can modify the flow structure to improve aerodynamic performance are much needed. The present study aims to provide a passive drag reduction method using the standard 35° Ahmed body. The classic rectangular slanted surface is replaced with elliptical to study the effect of reear geometry on aerodynamic performance. The study is conducted using the ANSYS FLUENT software at a Reynolds number of 7.8 × 105, based on the height of the model. The SST k-omega model is applied to solve the Navier-Stokes equations. The results show that the elliptical model reduced the drag by 10% compared to the classic rectangular geometry. The cause of this drag reduction is associated with the large modification of the flow structure in the wake region. Also, the reverse flow is observed to shift towards the vertical base compared to the standard model, where it exits away from the vertical base. The drag reduction is found to correlated with the recirculation modification. Therefore, this study provides detailed data and analysis of wake modification and drag reduction processes.
Learning and Engaging Through Transformative Informal Setting Driven by COVID Induced Leading Edge Virtual Technology for Advanced Fluid Mechanics Modeling and Simulations Seminar Series
Authors: Rodriguez Demy , Trevizo Leslie , Rodriguez Arturo , Aguilar Julio , Chijioke Clinton , Paez Brandon , Baez Rafael , Kotteda V. M. Krushnarao , Kumar Vinod 
Published: September 2022

Abstract
COVID-19 pandemic has forced students to learn about advanced scientific concepts, such as Fluid Mechanics and Modeling and Simulations, in a completely virtual setting. Such advanced concepts have traditionally been taught in face-to-face settings partially because these concepts require rigorous mathematical derivation and discussions. Pandemic has brought new challenges to educators to create engaging learning materials for students. The study indicates that students unconsciously absorb information that triggers motivation and endurance in students’ desire to pursue a lifelong research career. Pandemic however has brought new attention to technology development and created effective technology-driven solutions to learning needs for such concepts. Using the leading-edge technology, we have conducted extensive learning sessions for engineering undergraduate and graduate students for the last two years. In this paper, we will present a qualitative study aimed to understand the benefits of informal learning via advanced modeling and simulations seminar series. In this study, world-renowned STEM experts have given 45-minute seminar talks accompanied by 15-minute Q&A sessions to engineering graduate and undergraduate students, primarily from the University of Texas at El Paso. The seminar discussions, feedback, and comments were recorded using the Microsoft Teams video conferencing platform. We created this seminar series aimed to enhance and mitigate motivation losses faced during the COVID-19 pandemic. The goal lies in bringing students closer to new ways of learning, enhancing their knowledge not only in traditional classroom settings but also to motivate students and convince leaders to create dual engineering partnership study programs among the United States’ top universities for diverse groups of students to foster an atmosphere of collaboration and inclusion among the United States higher education systems. This study indicates that students unconsciously absorb information that triggers motivation and endurance in students’ desire to pursue a lifelong research career.
Mesh Adaptability Technique for Canonical Turbulent Jet Flows via Reinforcement Learning
Authors: Paez Brandon , Rodriguez Arturo , Kotteda V. M. Krushnarao , Chattopadhyay Ashesh , Terrazas Jose , Baez Rafael , Kumar Vinod 
Published: September 2022

Abstract
A combustion jet based on Sandia National Laboratories’ D Flame experiment will be studied computationally and validated by current available physical experimental results. In which the chemical reaction of methane-based fuel will be modeled. In which 36 species will be considered in the effects of entrainment, mixing, ignition and combustion. Based on the difficulty of finding the appropriate mesh, the most appropriate way to generate the mesh will be analyzed. A mesh refinement code incorporated into reactive foam will be used to supplement the OpenFOAM code used in this study. The P1 radiation model is used to exchange heat transfer, the k-e RANS model as our turbulence model, and the gases will be taken as compressible where the density changes. In addition to the mesh refinement code, Markov decision processes will be used to automate the mesh generation process based on reinforcement learning. In which reward and punishment will be used to train the network. Establishing a general and automated way to generate meshes in problems for national security in the matter of combustion based on jet flows.
Designing an Experimental Setup for Analyzing the Flow Through a 3D Printed Venous Valve System From Arthroscopic Images
Authors: Rascon Alan , Hossain Nazmul , Kotteda V. M. Krushnarao , Harris Christopher , Janssen Herbert , Dudrey Ellen , Kumar Vinod , Lopes Amit 
Published: September 2022

Abstract
Deep vein thrombosis (DVT) is a silent killer, with millions of fatalities worldwide and a higher rate occurring during the COVID 19 pandemic. DVT frequently starts as a thrombus in a venous valve pocket, typically in a person’s leg, with minimal-to-no manifestations in the beginning. The venous valve pockets reside behind a pair of leaflets. Working with the muscular system, they prevent the reverse/backward blood flow and promote normal venous blood flow from an extremity to the right heart. It is known that leaflet morphology plays an important role in valve function; however, the effects of leaflet damage on valve function have not been fully explored. This paper discusses an experimental model designed to investigate the role of normal and abnormal leaflet morphology on venous valve function. This is accomplished using a 3D printed valve modeled after arthroscopic images and flow conditions observed in human cadaveric veins. The visualization and evaluation of flow through the model 3D printed venous valve are subjected to qualitative and quantitative assessment to evaluate flow through the valve and trapping of fluid in the valve pocket.
High-Speed-Imaging-Supported Investigation of the Acoustics of Cavitation in an Industrial Centrifugal Pump
Authors: Gonschior Timo , Tilcher David Konstantin , Heinrich Antonia , Thamsen Paul Uwe 
Published: September 2022

Abstract
Cavitation is a common but undesirable phenomenon in the operation of centrifugal pumps. Methods to detect cavitation are needed to ensure safe operation. This study contributes to the approach of using acoustic signals for cavitation detection. Mainly focusing on microphone measurements, the effect of cavitation on frequency spectra at different positions around an industrial centrifugal pump are investigated. A method to systematically extract relevant frequencies that can be used as cavitation indicators is proposed. Various significant frequencies were found, distributed over the frequency range up to 30kHz. The cavitation on the impeller suction side was observed via a high-speed camera. A link between the optical appearance of the cavitation and the behavior of the indicator frequencies was apparent. Furthermore, a method for algorithmically evaluating the cavitation visible in high-speed imagery is presented and the synchronized optical and acoustical data was used to investigate the spectral change during transient cavitation events.
A Study of Microfluidic Device Geometries on Fluid Instabilities
Authors: Le Henaff Sylvain , Peterson Taylor , Hovell Candice , Mares Jeremy , Coathup Melanie , Reumers Veerle , Kinzel Michael 
Published: September 2022

Abstract
This effort is focused on studying fluid instabilities in microfluidic devices using Computational Fluid Dynamics (CFD) analysis to provide preliminary data for suborbital microgravity flight experiments. The experiments will utilize a lens-free imaging (LFI) system to capture and measure fluidic data. Various CFD models were created using Star-CCM+ to determine predicted Saffman-Taylor (viscous fingering patterns) instabilities in microfluidic devices using liquids with opposite viscosities. Lab data shows that channel height and inlet nozzle angles of the devices are dominant in the changing behavior of the instabilities. This study will focus on these parameters to further validate CFD results. It is expected that the device geometries will have a large impact on fluid instabilities in the microfluidic domain.
Quantifying Line-of-Sight Profile Nonuniformity Effect on Laser Absorption Spectroscopy Temperature Measurement via Data Analysis
Authors: Ruiyuan Kang , Liatsis Panos , Kyritsis Dimitrios C. 
Published: September 2022

Abstract
Some studies have qualitatively proved that nonuniform profiles along the light path in turbulent flows can cause temperature measurement inaccuracies in Laser Absorption spectroscopy (LAS), based on the analysis of Beer-Lambert’s law. In this work, we attempt to further analyze this nonuniformity effect quantitatively from the viewpoint of data analysis. Ten thousand synthetic CO2 absorption spectra are respectively generated from uniform profiles and five discrete sections nonuniform profiles. Sixteen machine learning/deep learning models are trained on the spectra of uniform profiles to estimate the (average) temperature. The top three models, i.e., VGG13, XGBoost, and GPR with constant kernel, are used to estimate the average temperature of nonuniform-profile spectra. Furthermore, the model sensitivities are examined for spectral twins, which have similar spectra appearance, but totally different temperature/concentration along the light path. The results demonstrate that while all models work well on uniformprofile spectra, the three best models cannot provide accurate average temperature estimation for nonuniform-profile spectra. The maximum of the absolute error can reach up to 942 K and the corresponding root mean squared errors (RMSE) are all above 200 K. Moreover, the top three models have weak sensitivity when it comes to distinguishing temperature differences between spectra twins, particularly when more stringent spectra twin selection criteria are used.
Large Eddy Simulation Study on the Application of a Whisker Structure to the Lip of a Trailing Edge Cutback
Authors: Luo Yuxi , Wen Fengbo , Sullivan Pierre , Wang Songtao , Wang Zhongqi 
Published: September 2022

Abstract
In this study, the whisker structure of a harbor seal is applied to the lip of a trailing edge cutback of gas turbine airfoils. A total of four whisker cases are studied as well as a prototype case and an elliptic lip case. Large Eddy Simulation is used to simulate the unsteady flow of the cutback cooling unit. The results show that the elliptic and whisker lip can significantly improve film cooling effectiveness. In particular, whisker Case-3 can achieve the best results at the medium blowing ratio. The analysis shows that the whiskered lip structure weakens the strength of the vortex shed from the lip. The decrease in the strength of the lip vortex weakens the effect of the lip vortex in entraining the mainstream high-temperature gas to the cutback surface and entraining the coolant away from the cutback surface. Therefore, the coverage effect of the coolant on the cutback surface is improved. Whisker Lip Case-3 has the separation shear layer converge from the crest to the trough, significantly reducing the film mixing process in the crest area. However, the mixing in the trough area does not increase significantly, which improves the overall film cooling effectiveness.