bluuebunny/crossref_metadata_2025 huggingface dataset:
Microcomputed tomography staging of bone histolysis in the regenerating mouse digit
Authors: Ketcham Paulina D. , Imholt Felisha , Yan Mingquan , Smith Hannah M. , Asrar Shabistan , Yu Ling , Dolan Connor P. , Qureshi Osama , Lin Yu‐Lieh , Xia Ian , Hall Patrick C. , Falck Alyssa R. , Sherman Kirby M. , Gaddy Dana , Suva Larry J. , Muneoka Ken , Brunauer Regina , Dawson Lindsay A.
Published: September 2022

Humans and mice have the ability to regenerate the distal digit tip, the terminal phalanx (P3) in response to amputation. What distinguishes P3 regeneration from regenerative failure is formation of the blastema, a proliferative structure that undergoes morphogenesis to regenerate the amputated tissues. P3 regeneration is characterised by the phases of inflammation, tissue histolysis and expansive bone degradation with simultaneous blastema formation, wound closure and finally blastemal differentiation to restore the amputated structures. While each regenerating digit faithfully progresses through all phases of regeneration, phase progression has traditionally been delineated by time, that is, days postamputation (DPA), yet there is widespread variability in the timing of the individual phases. To diminish variability between digits during tissue histolysis and blastema formation, we have established an in‐vivo method using microcomputed tomography (micro CT) scanning to identify five distinct stages of the early regeneration response based on anatomical changes of the digit stump. We report that categorising the initial phases of digit regeneration by stage rather than time greatly diminishes the variability between digits with respect to changes in bone volume and length. Also, stages correlate with the levels of cell proliferation, osteoclast recruitment and osteoprogenitor cell recruitment. Importantly, micro CT staging provides a means to estimate open versus closed digit wounds. We demonstrate two spatially distinct and stage specific bone repair/regeneration responses that occur during P3 regeneration. Collectively, these studies showcase the utility of micro CT imaging to infer the composition of radiolucent soft tissues during P3 blastema formation. Specifically, the staging system identifies the onset of cell proliferation, osteoclastogenesis, osteoprogenitor recruitment, the spatial initiation of de novo bone formation and epidermal closure.
Reviewer Acknowledgements for International Journal of Contemporary Education, Vol. 5, No. 2
Authors: Oscar William
Published: September 2022

International Journal of Contemporary Education (IJCE) would like to acknowledge the following reviewers for their assistance with peer review of manuscripts for this issue. Many authors, regardless of whether IJCE publishes their work, appreciate the helpful feedback provided by the reviewers. Their comments and suggestions were of great help to the authors in improving the quality of their papers. Each of the reviewers listed below returned at least one review for this issue.Reviewers for Volume 5, Number 2 Ahmad Suradi, State Islamic Institute of Bengkulu, IndonesiaAurora Q. Pestano, University of San Jose Recoletos, PhilippinesBožić-Lenard Dragana, University of Osijek Croatia, CroatiaDina Radeljas, Mohawk Valley Community College, USAEdward Bolden, Case Western Reserve University, USAFederica Cornali, University of Turin, ItalyFroilan Delute Mobo, Philippine Merchant Marine Academy, PhilippinesInaad M Sayer, University of Human Development, IraqIvan Lenard, Elementary School Ladimirevci, CroatiaLi Li, Bath Spa University, UKNesrin Ozturk, Izmir Democracy University, TurkeyNoelia Navarro Gómez, Universidad de Almería, SpainSuriadi Samsuri, Institute of Islamic Religion Sultan Muhammad Syafiuddin Sambas, Indonesia William OscarEditorial AssistantInternational Journal of Contemporary Education------------------------------------------------------------Redfame Publishing9450 SW Gemini Dr. #99416Beaverton, OR 97008, USATel: 1-503-828-0536 ext. 509Fax: 1-503-828-0537E-mail 1: ijce@redfame.comE-mail 2: ijce@redfame.orgURL: http://ijce.redfame.com
Stabilising function of the human diaphragm in response to involuntary augmented breaths induced with or without lower‐limb movements
Authors: Illidi Camilla R. , Romer Lee M.
Published: September 2022

New Findings

What is the central question of this study?

Is the stabilising function of the diaphragm altered differentially in response to involuntary augmented breaths induced with or without lower‐limb movements?

What is the main finding and its importance?

At equivalent levels of ventilation, the diaphragm generated higher passive pressure but moved significantly less during incremental cycle ergometry compared with progressive hypercapnia. Diaphragm excursion velocity and power output did not differ between the two tasks. These findings imply that the power output of the diaphragm during stabilising tasks involving the lower limbs may be preserved via coordinated changes in contractile shortening.

Activity of key respiratory muscles, such as the diaphragm, must balance the demands of ventilation with the maintenance of stable posture. Our aim was to test whether the stabilising function of the diaphragm would be altered differentially in response to involuntary augmented breaths induced with or without lower‐limb movements. Ten healthy volunteers (age 21 (2) years; mean (SD)) performed progressive CO2‐rebreathe (5% CO2, 95% O2) followed 20 min later by incremental cycle exercise (15–30 W/min), both in a semi‐recumbent position. Ventilatory indices, intrathoracic pressures and ultrasonographic measures of diaphragm shortening were assessed before, during and after each task. From rest to iso‐time, inspiratory tidal volume and minute ventilation increased two‐ to threefold. At equivalent levels of tidal volume and minute ventilation, mean inspiratory transdiaphragmatic pressure () was consistently higher during exercise compared with CO2‐rebreathe due to larger increases in gastric pressure and the passive component of (i.e., mechanical output due to static contractions), and yet diaphragm excursion was consistently lower. This lower excursion during exercise was accompanied by a reduction in excursion time with no difference in the active component of . Consequently, the rates of increase in excursion velocity (excursion/time) and power output (active × velocity) did not differ between the two tasks. In conclusion, the power output of the human diaphragm during dynamic lower‐limb exercise appears to be preserved via coordinated changes in contractile shortening. The findings may have significance in settings where the ventilatory and stabilising functions of the diaphragm must be balanced (e.g., rehabilitation).
Growth Mechanism of a Vortex Structure Formed by a Sweeping Jet and a Main Flow
Authors: Kobayashi Eisei , Fuchiwaki Masaki , Raghu Surya
Published: September 2022

The vortex structure generated by a single jet emit into the main flow is known as a jet in cross flow and is a fundamental phenomenon that has been reported in many studies. On the other hand, high-velocity, oscillating, sweeping jets are also attracting attention for their engineering applications, but the flow generated by sweeping jets emitted into the main flow is not fully understood due to a highly unsteady fluid phenomenon. In the present study, a large-scale vortex structure generated by a sweeping jet emitted into the main flow at an angle of 30 degrees from the wall is clarified through numerical simulation. Sweeping jets form a single stream tube near the outlet, specifically at z/d < 4.5, and gradually split into two stream tubes from z/d > 4.5. The vortex rings are generated by the interaction among the sweeping jet, the main flow, and the wall surface. The vortex rings tilt perpendicular to the main flow as they develop but dissipate due to the rotation of the high-velocity jet and transform into numerous elongated vortices.
Porous Media Model Parameter Development in Flame Arrestor Applications Numerical Study
Authors: Farah Hoden A. , de la Houssaye Bartley , Diaz Juan , Lu Frank K.
Published: September 2022

The flow characteristics, across a detonation flame arrestor in gas transport pipelines was studied in detail numerically. The pressure drop in the flame arrestor is predominantly associated with the crimp design of the flame arrestor element. The flow in the flame arrestor element is three dimensional, making it very challenging and computationally expensive for numerical modeling. To overcome the complexity of directly modeling the three-dimensional flow, a porous media model is developed using the Forchheimer equation. The coefficients of the Forchheimer equation were obtained from experiments and numerical simulation. The experimental method used test data on a small-scale crimped flame arrestor element. In the numerical method, a single triangular crimp-channel flow numerical simulation result was used to calculate the Forchheimer coefficients. Numerical solutions of flow across a small-scale flame element using the experimentally and numerically developed Forchheimer equations were verified experimentally. The result in both cases were validated to within five percent of experimental data. The flow characteristic result calculated using the numerically developed Forchheimer equation has similar accuracy as the experimentally developed coefficients. The simplification and advantages gained by developing the Forchheimer coefficients using numerical methods in flame arrestor applications is presented.
Development of Additional Material Transport to Augmented Reality Sandbox Algorithm to Model Pollution and Contaminant Runoff
Authors: Ainsworth Tyler , Smith Elizabeth
Published: September 2022

Augmented Reality (AR) sandboxes make use of play sand, a depth sensor (to sense the topography in the sand), a computer (to run calculations), and a projector (to display a responsive topographic height map onto the sand). AR sandboxes can be found in schools and museums across the world being used to teach students and patrons about topography, runoff, and other geological topics. The sandboxes provide a mixed reality experience as the users manipulate standard play sand but view simulated rain and water runoff. In this work, an additional transport equation is added to standard augmented reality sandbox algorithm. This transport equation allows modeling of contaminants as a point source or as runoff from a specified area. The transport of fluid and contaminants is driven by gravity and gradients across cells, The presence of pollution in the simulated water is displayed through a new visual texture with the color and opacity of the texture conveying the concentration of the contamination. The inclusion of this additional transport equation extends the educational application of the AR sandbox.
Methodology for Experimental Investigation of Hydraulic and Mechanical Characteristics of Ventricular Assist Devices
Authors: Strauch Carsten , Peter Julija , Thamsen Paul Uwe
Published: September 2022

Validation of flow topologies within rotary Ventricular Assist Devices (VADs) remains challenging due to small geometric dimensions of these pumps. Blood damage induced by VADs is suspected to be correlated to local flow patterns and therefore numerical simulation techniques established as a powerful tool for investigating local flow phenomena. Consequently, deep understanding of these flow fields contributes significantly to the design of blood-preserving Ventricular Assist Devices and increase life span of affected patients.

Different methods for verification of numerical simulations are available, but validations of applied turbulence models have so far been lacking. To close this knowledge gap, it is essential to examine flow fields inside a rotary blood pump by optical investigations. To realize optical accessibility for investigation of flow fields, and to validate turbulence models, it is necessary to abandon drive and bearing/suspension originally used in appropriate VAD designs. To draw reliable conclusions about hydraulic and mechanical characteristics, precise and reproducible investigations with low measurement uncertainty are mandatory. Only very accurate experimental results can be used to validate numerical simulations due to geometrical dimensions, constraints on manufacturing techniques, sensor accuracies, and materials.

In this paper a methodology is presented how to design the bearing/suspension of the impeller to fulfill mandatory requirements needed for validation of flow topologies. Furthermore, Gaussian Error Propagation is used to quantify achieved precision and reproducibility.
Effects of Tip Clearance on Internal Flow and Loss Generation Mechanism in an Axial Compressor at Windmilling Conditions
Authors: Inada Tomohiro , Sekino Ryousuke , Fujisawa Nobumichi , Ohta Yutaka
Published: September 2022

The internal flow structure and loss generation mechanism of a single-stage compressor during windmilling were investigated through experimental and computational analyses. The windmilling state occurs when the air flowing through an unlit engine drives the compressor rotor blades, similar to a turbine. This study focused on the effect of tip clearance size on the internal flow during windmilling operations. Therefore, detached eddy simulations were conducted at three tip clearance conditions: without clearance, design clearance, and wide clearance. Consequently, the total pressure loss decreased when the size of the tip clearance was expanded under windmilling conditions. In the windmilling state, separation on the pressure side due to the high negative incidence was generated, which was the main reason for the total pressure loss. When the size of the clearance increased, the size of the separation decreased because of the tip leakage flow. According to the detailed numerical results for the windmilling state, the leakage flow held the separation to the blade surface near the tip area. In addition, the tip leakage flow formed a blockage in the midchord, so the tip side of the separation vortex was moved to the midchord and formed a significant loss region. Thus, the tip leakage flow reduced the loss region, and the overall loss was reduced.
Mechanical Properties of Irreversible Gel Induced by Dosing With Surfactant Solution
Authors: Hirota Shin , Hara Shumpei
Published: September 2022

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

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

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 (> 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

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

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

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

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

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

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

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

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

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

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

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

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

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.
Effect of Actively-Controlled Trailing Edge Flap Upon Airfoil Energy Harvester
Authors: Strahl Jordan , Liburdy James
Published: September 2022

An experimental study was undertaken to evaluate the power extraction of an airfoil undergoing large amplitude pitching and heaving using a trailing edge flapping motion for the application of energy harvesting for steady flow over the airfoil. The airfoil was a NACA0015 design, pitching at the 1/3 chord position, with an actively controlled trailing edge flap hinged at the 2/3 chord location (chord length of c = 150mm and aspect ratio AR = 2, however end plates were used to simulate a two-dimensional airfoil). Data were obtained over a range of wind speeds corresponding to Reynolds numbers in the 30,000–60,000 range in a low-speed wind tunnel with turbulence intensities below 2%. The results are characterized using the reduced frequency, k = fc/U∞ over the range of 0.04–0.08, where f is the oscillating frequency in Hz, and U∞ is the freestream velocity. The pitching and heaving amplitudes are θ0 = 70° and h0 = 0.6c respectively, with a phase delay of 90°. Two trailing edge motion profiles are presented, examining the relative phase of trailing edge flap to the pitching phase. For each motion, a positive and negative case are considered. This is a total of 4 trailing edge motion profiles. Trailing edge motion amplitudes of 20° and 40° are compared and results contrasted. Direct transient force measurements were used to obtain the cycle variation of induced aerodynamic loads (lift coefficient) as well as the power output and efficiency. Results are used to identify the influence of trailing edge flap oscillations on the overall performance for energy harvesting, with a maximum efficiency increase of 21.3% and corresponding cycle averaged heaving power coefficient increase of 29.9% observed as a result of trailing edge motion.
Data-Driven Dynamical System Models of Roughness-Induced Secondary Flows in Thermally Stratified Boundary Layers
Authors: Hansen Christoffer , Yang Xiang I. A. , Abkar Mahdi
Published: September 2022

The goal of this work is to investigate the feasibility of constructing data-driven dynamical system models of roughness-induced secondary flows in thermally stratified turbulent boundary layers. Considering the case of a surface roughness distribution which is homogeneous and heterogeneous in the streamwise and spanwise directions, respectively, we describe the streamwise averaged in-plane motions via a stream function formulation, thereby reducing the number of variables to the streamwise velocity component, an appropriately introduced stream function, and the temperature. Then, from the results of large-eddy simulations, we perform a modal decomposition of each variable with the proper orthogonal decomposition and further utilize the temporal dynamics of the modal coefficients to construct a data-driven dynamical system model by applying the sparse identification of nonlinear dynamics (SINDy). We also present a novel approach for enforcing spanwise reflection symmetry within the SINDy framework to incorporate a physical bias.
Simulation-Driven Blade Work Distribution Based Design Strategy and Optimization of a Low-Pressure Axial Fan
Authors: Fritsche Manuel , Epple Philipp , Delgado Antonio
Published: September 2022

Low pressure axial fans have a very wide range of applications in the field of heating, ventilation and air conditioning as well as refrigeration (HVAC&R). Due to stricter legal requirements, increasingly higher minimum fan efficiencies are required. That is why the optimized design of the fan is a crucial point in the development process. Therefore, the simulation-driven preliminary design strategy and optimization is very important in the product development of low-pressure axial fans.

For a specified design point, the blade work distribution along a finite partial section of the impeller flow channel was predetermined. From that, the distribution of the meridian velocities was computed applying the simplified radial equilibrium and the Euler equation for turbomachinery. Then, the blade angles, i.e. the shape of the blade of the axial impeller, were determined. Using the continuity equation and the simplified radial equilibrium, the method has also been extended for non-constant hub shapes, for example a conical hub shape. The blade shape was parameterized by 9 angles, i.e. three angles at the impeller inlet (leading-edge section), three angles at the mid-streamwise section and three angles at the impeller outlet (trailing-edge section).

The angles for the hub plane, the mid-span plane and the shroud plane were determined accordingly. The geometry of the impeller was generated, modeled and solved for the performance characteristics with the numerical flow simulation software ANSYS CFX.

In a subsequent optimization process, based on these pre-designs the parameter space of the leading edge was populated by a DOE analysis using the Latin Hypercube sampling method. Then a multi-objective optimization procedure (MOGA-II) has been performed with the optimization constraints of maximum efficiency and maximum pressure and, at the same time, minimum flow blocked area in the blade channel. From this optimization approach the optimal design was determined, i.e. the optimal angles at the impeller inlet (leading-edge). The same optimization procedure was then also conducted for the mid-streamwise angles and finally for the angles at the impeller outlet at the blade trailing-edge.

Then, for the optimized axial fan, the complete performance characteristics, i.e. at the design and off-design points, have been calculated with CFD showing very good improvements over the full performance characteristics. The method and the results are discussed in detail.
The Effects of Aspect Ratio on Turbulence Wake Flow Over Right Trapezoidal Prism
Authors: Kang Jinhao , Kumahor Sedem , Sagharichi Amir , Tachie Mark F.
Published: September 2022

The shear layer and the near wake region of right trapezoidal prisms with varying streamwise aspect ratios in a uniform flow were investigated using particle image velocimetry. The tested streamwise aspect ratios (AR) based on the height and upper surface were 1 and 4. The Reynolds number based on the prism height and the freestream velocity was 14700. The effects of aspect ratio on the mean flow, Reynolds stresses and third-order moments were investigated, and the results were compared with a square prism. The results show that mean flow separation at the leading edge is not affected by the different geometries and the streamwise aspect ratios. However, the mean recirculation bubbles over the prism and in the wake region show significant differences. Mean flow reattaches over the prism in the AR4 case, but there is no reattachment in the AR1. One-dimensional profiles are used to quantitatively assess the differences in the flow characteristics. It is observed that the magnitudes of Reynolds stresses in the near wake region are an order higher in the AR1 case than in the AR4 case.
Body Shape Effects on the Hydrodynamic Performance of Bio-Inspired Undulating Swimmers
Authors: Kelly John , Pan Yu , Dong Haibo
Published: September 2022

In this study, numerical simulations are performed to study the effects of body shape on propulsive performance in a carangiform-like swimming motion. A focus is given to the variation in performance due to changes in the maximum thickness, maximum thickness location, leading-edge radius, and boattail angle of an undulating foil. An immersed boundary method-based incompressible flow solver is implemented to solve for the propulsive performance of two-dimensional undulating foils. The resulting flow simulations yield the thrust, drag, efficiency, and flow for each body shape. From this study, we have found that better propulsive performance comes from a thinner maximum thickness, a maximum thickness location closer to the head of the fish, a narrower boattail angle, and a larger leading-edge radius. Particular care is given to the analysis of the boattail angle, because of the surprising and significant results. In changing only the boattail angle the efficiency is shown to vary by 10.3%. Changes in the leading-edge radius varies the efficiency by 4.4%, the maximum thickness by 4.0%, and the maximum thickness location along the body by 5.0%. The large improvement observed in the thinner boattail angle cases are caused by the increased curvature around the middle of the fish body leading to a high-pressure region at the tail that improves the thrust performance. The results can be used to improve understanding of fish body shapes observed in nature as well as better informing the design of bio-inspired underwater robots.
A Numerical Study on the Effect of Carrier Fluid Subgrid Scales Fluctuations on Deposition and Dispersion of Lagrangian Particles
Authors: Rousta Farid , Lessani Bamdad , Ahmadi Goodarz
Published: September 2022

Large-eddy simulation (LES) coupled with a Lagrangian particle tracking was performed, and the particle deposition and dispersion in turbulent channel flows were investigated. Different test cases with particle Stokes numbers varying from St = 2 to St = 100 were considered in a fully developed turbulent channel flow at a friction Reynolds number of Reτ = 180. The Dynamic Smagorinsky model was used to model the sub-grid scale fluctuations of carrier flow. In the first set of simulations, the effects of sub-grid scale fluctuations in LES were not considered on the Lagrangian particles. Instead, the velocity of carrier flow seen by particles was simply taken as the fluid filtered velocity. Next, direct numerical simulations (DNS) for the same test cases were performed to clarify the importance of sub-grid scale fluctuations seen by the Lagrangian particles. To clarify the differences, the predicted deposition velocities predicted by both LES and DNS methods were compared with the available data in the literature. Deposition velocities predicted by LES were significantly less than those predicted by DNS, especially for the cases with lower particle Stokes numbers. In addition to the deposition velocity, the particle dispersion was also significantly affected by the sub-grid scale fluctuations in the channel. To shed light on differences between particle dispersion for different cases, time and space averaged particle concentrations were evaluated and compared. Finally, the particle mean and fluctuating velocity profiles for different cases were reported.