bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modified Operating Parameter-Based Iyer Correlation for the Coefficient of Performance (COP) Prediction of Different Fluid Pairs in Double-Effect Vapor Absorption Refrigeration (VAR) Cycles
Authors: Khan Muhammad Saad , Kadam Sambhaji T. , Kyriakides Alexios-Spyridon , Hassan Ibrahim , Papadopoulos Athanasios I. , Rahman Mohammad Azizur , Seferlis Panos 
Published: October 2021

Abstract
Vapor absorption refrigeration (VAR) is a sustainable alternative to the conventional vapor compression refrigeration (VCR) cycle, owing to its lower non-renewable energy requirements and potentially for exploitation of renewable energy sources. Traditionally, the coefficient of performance (COP) of the conventional single effect VAR cycle is considerably lower than VCR cycles. This provides room for improvement which can be attained through double effect VAR cycles that provide relatively higher performance. The COP of the dual effect VAR cycle is enhanced due to the waste/rejected heat energy utilization from the condenser or the absorber into a secondary generator. Models that correlate the COP of the double effect VAR cycle with operating parameters are not available in the open literature, with Iyer’s correlation being the only exception. This work applies this COP correlation using literature data for double effect VAR that operate with a variety of refrigerant and absorbent pairs. A comprehensive Mean Absolute Percentage Error (MAPE) analysis is performed for more than 2028 data points of various fluid pairs. Results reveal that MAPE (86.6–839%) values appear to be quite high for the reported correlation. Furthermore, the model is optimized using the proposed data set, considerably reducing the MAPE up to 36.03%. The results also indicate that due to the lack of fluid-specific parameters, the application of this correlation may not support the development of new double effect VAR cycles. Therefore, it is crucial to establish a performance-based correlation that considers both operational parameters and fluid parameters to assess the performance of new and efficient dual effect VAR cycles.
CFD Analysis on Biogas Bubble Creation Within a Stirred Tank of a Wastewater Treatment Plant
Authors: Dabiri Soroush , Rauch Wolfgang 
Published: October 2021

Abstract
A mixing strategy for assuring a homogeneous fluid flow inside wastewater treatment plants (WWTPs) is a necessity, in order to keep continuous contacts of substrates and degraders. On the other hand, mixing is an energy-demanding process. Therefore, the power consumption for mixing the fluid flow within bioreactors affects the overall efficiency of WWTPs. The current study aims at evaluating the incorporation of biogas bubble creation on the mixing of WWTP tanks. Computational fluid dynamics (CFD) enables simulating hydrodynamics of multiphase fluid flows injected with bubble parcels. The case is a cylindrical stirred tank, in which the fluid flow is agitated via a rotating mixer. Mixer rotates at various speeds; and for each case, the ultimate fluid flow is captured both with and without bubble creation. Non-Newtonian characteristics of the fluid flow within the tank are considered and k–ε turbulence closure is selected for the model. By a two-way coupling of an Eulerian-Lagrangian platform, velocity fields and the amount of dead volume are analyzed and discussed.
Our key finding is that the biogas bubble creation contributes to the reduction of dead volume inside the WWTP tank, when there is no external rotating mixing, or once the amount of mixer rotation speed is low.
Computational Fluid Dynamic Analysis of the Flow Around a Propeller Blade of Multirotor Unmanned Aerodynamic Vehicle
Authors: Martinez Victor H. , Bhaganagar Kiran 
Published: October 2021

Abstract
Multirotor Unmanned Aerodynamic Vehicles (MUAV) have been a high interest topic in the aerodynamic community for its many applications, such as, logistics, emergency rescue, agriculture data collection, and environmental sensing to name a few. MUAV propeller blades create a highly complex turbulent fluid flow around the body and the environment around it. The flow physics generated from the rotation of the propeller blades were studied in this paper along with the analysis of aerodynamic characteristics. A Reynolds Average Navier-Stokes (RANS) Computational Fluid Dynamics (CFD) analysis of a propellor blade from a MUAV has been performed to quantify the aerodynamic effects. For this purpose, the verification and validation of the commercially available CFD solver COMSOL Multiphysics v5.5 was performed using the NACA 0012 airfoil which is one of the most highly studied of the NACA family. With this validation it created confidence on the results for simulating a MUAV propeller and evaluate the aerodynamic characteristics of thrust coefficient (KT), power coefficient (KP), and Efficiency (η). These characteristics were compared against experimental data and results showed to have a similar trend. This showed that the CFD solver is capable of solving the aerodynamic characteristics of any propeller blade geometry.
Aerodynamic Performance of Design for a CO2 Dragster
Authors: Paez Brandon , Rodriguez Arturo , Dudu Nicholas , Terrazas Jose , Adansi Richard , Kotteda V. M. Krushnarao , Aguilar Julio C. , Kumar Vinod 
Published: October 2021

Abstract
The CO2 Dragster competition is performed at a national level as part of the Technology Student Association (TSA), and it seeks to increase and implement STEM skills for high school students. Students are expected to create CO2-powered Dragsters, which are placed on a 20-meter track to compete against each other. The CO2 Dragster consists of a pressure vessel containing CO2, which is placed in a pre-drilled cartridge located at the back of the vehicle. The CO2 propellant is used to provide thrust to the Dragster during the race, and sand smoothed balsawood material is used for the solid body of the Dragster. The CO2 Dragster competition is introduced at the high school level to provide students with a hands-on activity that allows them to learn and apply the fundamentals of fluid dynamics and solid mechanics. The students are placed in charge of designing a 3D model of their Dragster and are required to submit the 3D model with their respective drawings. In this paper, a mathematical, computational, and experimental analysis of a CO2 Dragster is provided. This research consisted of creating a shell model on NX 10, then inserted into ANSYS Fluent to simulate the flow around the model to identify and track the stagnation points, pressure loadings, and flow separation effects caused by the fluid interaction with the Dragster. Mathematical formulas were implemented to find the fracture of slim body CO2 Dragsters, using a coupling between fluid mechanics and solid mechanics, Fluid-Structure Interactions (FSIs). In conclusion, by creating a computational model, it is possible to drive dragster design by simulating different dragster designs’ computationally to improve its performance. Creating a computational functional model to simulate the Dragster, implementing mathematical formulas to understand the behavior, and experimentally evaluating the parameters based on performance will lead to more innovative practices of creating better Dragsters for this competition.
Experimental Evaluation of Novel Swirl Flow Air-Water Separation Apparatus for Desalination/Water Remediation Applications
Authors: Thyagarajan Ashok , Banerjee Debjyoti , Dhir Vijay 
Published: October 2021

Abstract
A novel apparatus that is capable of dynamic flash evaporation and phase separation using centrifugal flow (i.e., using a Hydro-Cyclone Apparatus/HCA) is evaluated in this study. The objective of this study is to evaluate the performance of a novel phase separator apparatus that forms a stable air core at the center from a premixed air-water mixture. The air core is retrieved using a retrieval tube placed at the center of the test section. Experiments were performed by varying the inlet volume flow rates of air and water to determine the maximum separation efficiency and plot its variation as a function of inlet air and water flow rates. The data obtained from this study is used as a preliminary indicator of the anticipated range of separation efficiencies for the system during experiments involving phase change for the production of potable water from saline water for water remediation applications.
Experimental Measurement of Oil Droplets Size and Velocity Above the Rotor/Stator in a Rotary Compressor
Authors: Wu Puyuan , Chen Jun , Sojka Paul E. , Li Yang , Cao Hongjun 
Published: October 2021

Abstract
Hundreds of millions of Air conditioning (AC) systems are produced each year. Many of them, especially small AC appliances, use rotary compressors as the system’s heat pump due to their simple structure and high efficiency in a small system. Lubricant oil is used in the rotary compressor to lubricate the moving parts, such as the crankshaft and the rolling piston, and to seal the clearance between the sliding parts, e.g., the clearance between the rolling piston and the cylinder, and the vane and the cylinder. As the compressed refrigerant vapor is discharged from the cylinder through the discharge port, part of lubricant oil in the cylinder would be carried by the vapor and atomize into small droplets in the lower cavity during the discharge process, which is complicated and highly-coupled. Some of these oil droplets would ultimately be exhausted from the compressor and enter other parts in the system, reducing the compressor reliability and deteriorating the heat transfer of the condenser and the evaporator in the system. Our previous research studied the atomization of the lubricant oil during the discharge process in the compressor’s lower cavity. However, the oil droplets’ behavior downstream of the lower cavity is unknown. Thus, studying the oil droplets’ behavior after passing through the rotor/stator can help understand how the rotor/stator would affect the droplet size distribution and movement, thus controlling the flow rate of escaped oil droplets. In this study, a hot gas bypass test rig is built to run a modified rotary compressor with sapphire windows right above the rotor/stator. The oil droplets’ size distribution and movement along the radial direction are obtained at the shaft’s rotating frequency of 30 and 60 Hz by shadowgraph. It is found that droplet size at 30 and 60 Hz varies little in the inner region of the rotor/stator clearance and would increase sharply above the clearance and keep increasing in the outer region of the clearance. More importantly, droplet velocity has a downward velocity component at the inner region and an upward velocity component at the outer region of the rotor/stator clearance. With the result of droplet size distribution and droplet velocity above the rotor/stator, we propose the model of the oil droplet’s path above the rotor/stator, which can be understood as the coupling of a swirling jet and a rotating disk.
A Comprehensive Review of Three-Dimensional Neuro-Organoids and Engineering Brain-on-a-Chip Microfluidic Devices
Authors: El Nihum Lamees , Shettigar Nandan , Banerjee Debjyoti , Krencik Robert 
Published: October 2021

Abstract
The focus of this review is to describe advances in three-dimensional (3D) organoids reported in the literature with an emphasis on the engineering of microfluidic device platforms for investigating neuro-organoids. Furthermore, the paper will assess current limitations in microfluidic design that must be addressed for realizing the full potential of brain-on-a-chip devices.
Turbulent Flow Simulation of Supercritical Hydrothermal Synthesis in T-Shaped Channel
Authors: Furusawa Takashi , Matsui Kenta , Yatsuyanagi Shuto , Yamamoto Satoru , Yoko Akira , Adschiri Tadafumi 
Published: October 2021

Abstract
Turbulent mixing flows of supercritical water and a metal-salt solution were investigated using Reynolds-averaged Navier–Stokes (RANS) simulations. The mass conservation equations for metal-salt and metal-oxide in an aqueous solution, which were coupled with Navier–Stokes equations and the Shear Stress Transport (SST) turbulence model, were solved by considering production by the hydrothermal reaction. The reaction rate in the numerical simulation was interpolated linearly using the experimental data. The mixing flows in a T-shaped channel for various Reynolds numbers were simulated numerically. Fluid mixing causes a hydrothermal reaction in a high temperature region. In a situation with a low temperature and low Reynolds number, the mixing became a steady state, and the metal oxide was generated along the channel wall. For a high Reynolds number, the periodic vortexes were observed at the mixing point and the fluid temperature increased rapidly. A numerical simulation reproduced the apparent reaction rate of the experimental measurements, except for the low Reynolds number case. The time-averaged temperature distributions indicated that the increasing temperature rate in the mixing reactor depends on the inlet supercritical water temperature, which affects the distribution of the concentration of metal oxide. If the turbulence effects were ignored in low-temperature instances, the apparent reaction rate was estimated to be quite low. The turbulent diffusivity and thermal conductivity crucially affected the conversion rate, especially for conditions with a low Reynolds number.
Large Scale Structures in Elevated Jet Normal to Crossflow
Authors: Gupta Jyoti , Saha Arun K. 
Published: October 2021

Abstract
Transverse jet from elevated source is found in various environmental and industrial field which include smoke exhausting from stack into atmosphere and sewage water disposal in deep-ocean. The experiment is carried out in water tunnel using flow visualization and Laser Doppler Velocimetry. Analysis has been performed for axisymmetric round jet of aspect ratio of 9.0 with the velocity ratio varying up to 2.5 at Reynolds number (based on free stream crossflow velocity and jet external diameter) of 1000. Result shows the formation of different jet shear layer vortices with varying velocity ratio are: (i) clockwise-downwash vortices (velocity ratio less than 0.3), (ii) delayed-regular-clockwise vortices (between 0.3 to 0.7), (iii) regular-clockwise vortices (between 0.7 to 1.4) at the lee side of the jet shear layer, (iv) irregular-anticlockwise vortex at the upstream along with clockwise vortices at the lee side of the jet shear layer that together forms mushroom vortices (between 1.4 to 1.9) and (v) regular-mushroom vortices (above 1.9). The other vortices found are stack-end vortex (less than 0.9) in the wake near free end, upright vortices (above 0.9) in jet-wake and hairpin vortices (between 0.3 to 0.6) in downstream which is the stretched part of evolving shear layer.
Inverse Problems in Magnetic Resonance Velocimetry: Shape, Forcing and Boundary Condition Inference
Authors: Kontogiannis Alexandros , Juniper Matthew 
Published: October 2021

Abstract
We derive and implement an algorithm that takes noisy magnetic resonance velocimetry (MRV) images of Stokes flow and infers the velocity field, the most likely position of the boundary, the inlet and outlet boundary conditions, and any body forces. We do this by minimizing a discrepancy norm of the velocity fields between the MRV experiment and the Stokes problem, and at the same time we obtain a filtered (denoised) version of the original MRV image. We describe two possible approaches to regularize the inverse problem, using either a variational technique, or Gaussian random fields. We test the algorithm for flows governed by a Poisson or a Stokes problem, using both real and synthetic MRV measurements. We find that the algorithm is capable of reconstructing the shape of the domain from artificial images with a low signal-to-noise ratio.
Liutex and Third Generation of Vortex Identification
Authors: Yu Yifei , Nottage Charles , Alvarez Oscar , Liu Chaoqun 
Published: October 2021

Abstract
Scientists developed many vortex identification methods and Liu classified the traditional vortex identification methods into two generations. Vorticity and vorticity-based methods belong to the first generation while eigenvalues-based methods are considered as the second generation, such as Q criterion and λci method. However, although these methods are widely used, there is still room for improvements. People used to consider direction of vorticity is the swirling axis and the magnitude of it is the rotation strength, but the predictions by vorticity does not match the experiment very well which drove scientists to develop the second-generation methods. All the second-generation methods are scalar-valued and as a result they are unable to locate the swirling. Another problem is even though second-generation methods can predict vortex better than vorticity, they are more or less contaminated by shear. To solve these problems, Liu innovated Liutex recently. Liutex is a vector quantity whose direction represents rotation axis and whose magnitude represents rotation strength. Firstly, the physical essence of rotation axis is provided coming with the mathematical definition of swirling axis which is the direction of Liutex. Secondly, orthogonal transformations are used to find out the rigid rotation speed and that speed is defined as the strength of Liutex. Wang later proposed an explicit formula to calculate Liutex strength without doing orthogonal transformations which makes it much easier to apply Liutex method. Some theories dependent on Liutex concept have been proposed these years. Liutex core lines represent the core of vortex which can uniquely and clearly show vortex structure. Principal coordinate is a special coordinate in which it is easy to decompose the velocity gradient tensor into rotation, shear and stretching parts correctly. And principal decomposition is the decomposition in principal coordinate. The Liutex theory system is gradually formed and they are considered as the third generation by Liu.
Harnessing the Power of the Cloud - Computational Fluid Dynamics With SimScale
Authors: Murad Jousef 
Published: October 2021

Abstract
Computational fluid dynamics is a computational method that enables engineers and designers to study the motion of fluids through computer simulations and modelling. Many tools on the market are so-called “in-house” tools requiring a certain level of expertise and upfront investment before proving their added value. Facilitated by the emergence of cloud computing, computer-aided engineering (CAE) technology is now offered as a software as a service (SaaS) solution, which increases its accessibility and ease of use. Online fluid flow (CFD) simulation is used in addressing a broad variety of problems like electronics design or pedestrian wind comfort (PWC), allowing engineers to accurately predict fluid flow behaviour guiding them towards smarter design decisions. SimScale is creating a paradigm shift for high-performance computing which can solve several problems that are faced when using on-premises software.
Military families: the impacts of having a first child during service on military mothers
Authors: Williamson Charlotte , Baumann J , Murphy D 
Published: October 2021

IntroductionThe rights, roles and responsibilities of servicewomen in the UK Armed Forces has changed dramatically over time. Previously, service personnel were automatically discharged from the military if they became pregnant. As the percentage of servicewomen in the UK Armed Forces increases, having children during service is becoming more common and maternity policies are now in place. Having children during military service can impact on the health and well-being of servicewomen, including a greater risk of illness when returning to work.MethodsA cross-sectional, self-report survey was used for data collection. The response rate was approximately 45%. Female Army veterans were recruited via a female military association. The survey collected data on parental status, the timing of their first child (during or after service), and several current mental and physical health and well-being outcomes.ResultsOf the 750 female Army veterans who completed the survey, 406 reported having children. Of those with children, 14.5% had their first child during service compared with 85.5% after service. The most frequently endorsed health outcomes were low social support, loneliness and common mental health difficulties. Participants who had their first child during military service were more likely to have left the service non-voluntarily.ConclusionsThis study provided insight into the impacts of having a first child during military service on servicewomen. Overall, female Army veterans who had their first child during service had poorer outcomes, including leaving service non-voluntarily. However, none of the health or well-being outcomes remained significant after adjusting the results. This study explored a widely under researched population and field of research. Future research should seek to expand on our findings and continue to explore the impacts of having a first child during military service for military mothers.
Maternal vitamin D intake and BMI during pregnancy in relation to child’s growth and weight status from birth to 8 years: a large national cohort study
Authors: Amberntsson Anna , Papadopoulou Eleni , Winkvist Anna , Lissner Lauren , Meltzer Helle Margrete , Brantsaeter Anne Lise , Augustin Hanna 
Published: October 2021

ObjectivesTo examine the associations between maternal vitamin D intake and childhood growth and risk of overweight up to 8 years. We further examined the effect modification by maternal prepregnancy body mass index (BMI).DesignProspective population-based pregnancy cohort study.SettingThe Norwegian Mother, Father and Child Cohort Study.ParticipantsIn total, 58 724 mothers and 66 840 singleton children, with information on maternal vitamin D intake during the pregnancy and minimum one postnatal anthropometric measurement.Outcome measuresPredicted weight and height growth trajectories and velocities from 1 month to 8 years, rapid growth during infancy and toddlerhood, and risk of overweight in preschool and school age.ResultsOverall, maternal vitamin D intake was associated with lower weight trajectory, lower odds of rapid weight growth and higher odds of childhood overweight. In children of mothers with prepregnancy normal weight, maternal vitamin D intake was negatively associated with weight trajectory and lower OR of a rapid weight growth during the first year, compared with reference (<5 µg/day). Children of mothers with normal weight, with maternal vitamin D intakes of 10–15 and >15 µg/day, also had 0.86 (95% CI 0.77 to 0.97) and 0.88 (95% CI 0.79 to 0.99) lower odds for overweight at 3 years, compared with reference. In contrast, in children of mothers with prepregnancy overweight (BMI ≥25 kg/m2), vitamin D intake was positively associated with weight trajectory. Children of mothers with overweight, with maternal vitamin D intake of 5–9.9 µg/day, also had (1.09 (95% CI 1.01 to 1.18) and 1.12 (95% CI 1.02 to 1.23)) higher odds for overweight at 5 years and 8 years, compared with reference.ConclusionsMaternal vitamin D intake affects postnatal growth and is inversely associated with childhood overweight in children of mothers with normal weight. Associations between maternal vitamin D intake and child growth and risk of overweight varied by prepregnancy BMI.