bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wake Properties of an Oscillating Airfoil Undergoing Small Amplitude Asymmetric Oscillation
Authors: Stutz Colin , Bohl Douglas , Green Melissa 
Published: October 2020

Abstract
The flow around, and in the wake of, pitching airfoils has received renewed interest due to its potential for thrust production at low Reynolds numbers. Past work has centered on the flow fields generated by symmetric pitching of the airfoil. Studies investigating the effects of asymmetric motion are more limited. This work focuses on the wake patterns developed due to asymmetric pitching. Particle Image Velocimetry (PIV) is used to quantify the flow field around a NACA0012 airfoil undergoing small amplitude, high frequency asymmetric pitching. The airfoil is pitched about the quarter chord point with an amplitude of ±4° at reduced frequencies of k = 2.6–5.8 at a Rec = 12000. Pitching symmetries of 50/50, 40/60 and 30/70 are studied, where the symmetry is defined by the fraction of the cycle spent in the pitch down versus pitch up motion. The data show that for the 50/50 (symmetric) motions two alternating sign vortices, with equivalent strength, are formed as expected. The asymmetric cases show that a single vortex is formed during the “fast” portion of the pitching motion. Multiple vortices are formed during the “slow” portion of the pitching motion. The number of secondary vortices and the downstream evolution of the vortices depends on the symmetry value. In some cases they remain isolated but orbit other vortical structures, while in other cases they pair with other vortical structures, and finally when the reduced frequency and asymmetry values are high enough the vortex array shows interaction between cycles.
Effect of Head Posture on Airflow and Pressure Behavior of Human Upper Airway During Snoring
Authors: Wang Junshi , Han Pan , Tang Ruixuan , Tang Hong , Kwon Younghoon , Xi Jinxiang , Dong Haibo 
Published: October 2020

Abstract
Snoring is a common breathing disorder during sleep. It is hypothesized that head posture during sleep could change the bending angle and the cross-sectional area of the airway, which could cause changes in airflow and aerodynamic pressure during sleep. In this work, an experiment-driven computational study was conducted to examine the aerodynamics and pressure behavior in human upper airway during snoring. An anatomically accurate human upper airway model associated with a dynamic uvula was reconstructed from human magnetic resonance image (MRI) and high-speed photography. The airway bending at different head posture and the corresponding change in airway cross-sectional area are modeled based on measurements from literature. An immersed-boundary-method (IBM)-based direct numerical simulation (DNS) flow solver was adopted to simulate the corresponding unsteady flows of the bent airway model in all their complexity. Analyses were performed on vortex dynamics and pressure fluctuations in the pharyngeal airway. It was found that the vortex formation and aerodynamic pressure were significantly affected by the airway bending. A head-neck junction extension posture tends to facilitate the airflow through the upper human airway. Fast Fourier transformation (FFT) analysis of the pressure time history revealed the existence of higher order harmonics of base frequency with significant pressure amplitudes and energy intensities. The results of this study help better understand the pathology of snoring under the influence of head posture from an aerodynamic perspective.
On the Application of the Full Reynolds Stress Model for Unsteady CFD in Hydraulic Turbomachines
Authors: Casartelli Ernesto , Mangani Luca , Roos David , Del Rio Armando 
Published: October 2020

Abstract
The computation of the characteristic of hydraulic machines, both in pump and turbine mode, needs, when performed over a wide operating range, to take into account turbulence anisotropy. This because highly separated flows largely deviate from isotropic turbulence structures as assumed in RANS eddy viscosity models with the Boussinesq approximation. In this paper CFD computations were performed with anisotropic turbulence models in order to capture the characteristic and investigate flow structures phenomena. Experimental results are compared against the CFD simulations in order to validate the results. Specific occurring phenomena are highlighted and more complex flow structures are evident compared to those computed with standard eddy viscosity models. A in-house pressure based coupled solver was used for the CFD simulations. The code is a finite volume polyhedral CFD solver implemented in a C++ framework with the possibility to implement implicit and coupled algorithms. Second moment closure turbulence model have been successfully implemented with a standard and novel fully coupled algorithm. In the paper the advantage of the novel algorithm is presented for industrial applications. The fully coupled approach for the Reynolds Stress model allows stable simulations of transient and steady state hydraulic machines at any operating point, opening also new opportunities in obtaining high accurate results for anisotropic turbulent flows without the usage of hybrid LES/RANS models and without the model limitation of standard eddy viscosity models.
Modeling Microbubble Microvessel Interaction for Sonoporation Application
Authors: Gnanaskandan Aswin , Deng Xiaolong , Hsiao Chao-Tsung , Chahine Georges 
Published: October 2020

Abstract
Modeling the dynamics of microbubbles inside confined spaces has many potential applications in biomedicine, sonoporation being one classic example. Sonoporation is the permeabilization of a blood vessel’s endothelial cell membrane by acoustic waves in order to non-invasively deliver large-sized drug molecules into cells for therapeutic applications. By controlled activation of ultrasound contrast agents (UCA) in a microvessel, one can achieve better permeabilization without causing permanent damage associated with high intensity ultrasound. This paper considers numerically, the fluid-structure interactions (FSI) of UCA microbubbles with a microvessel accounting for large deformations. The modeling approach is based on a multi-material compressible flow solver that uses a Lagrangian treatment for numerical discretization of cells containing an interface between two phases and an Eulerian treatment for cells away from material interfaces. A re-mapping procedure is employed to map the Lagrangian solution back to the Eulerian grid. The model is first validated by simulating a microbubble oscillating due to an imposed ultrasound inside a microvessel and good agreement with experiments is obtained for both the bubble and vessel dynamics. The effect of vessel elasticity is then studied and it is shown that increasing the vessel elasticity damps the bubble oscillations. Then the effect of placing the bubble away from the axis of vessel is studied and it is shown that bubbles closer the vessel wall are capable of creating maximum deformation on the wall compared to those away from the wall.
Two-Dimensional CFD Study on the Enhancement of Tube Bank Configuration Heat Exchanger
Authors: Elmekawy Ahmed M. Nagib , Shahin Abdalrahman M. , Ibrahim Alaa A. , Al-Ali Sara 
Published: October 2020

Abstract
Two-dimensional simulations are carried out for a heat exchanger to study the cross-flow behavior in a circular tube bank in a staggered configuration in case of bare cylinders and cylinders with splitter plate attachment. A considerable performance evaluation of the heat exchanger with splitter plate can be achieved by studying the heat transfer and the pressure drop of the flow. Numerical simulation results carried out from this study are compared to experimental results. The numerical investigation has been established to study the effect of splitter plate on the heat exchanger thermal performance as there were no previous studies performed on the optimization of the splitter thickness. The study also illustrates the effect of splitter plate thickness variation on pressure drop and heat transfer for different Reynolds number.
Passive Bristling of Shark Skin Scales at the Micro-Level: A Fundamental Viscous Flow Study to Understand the Separation Control Mechanism
Authors: Prichard Reid , Strasser Wayne , Cherok Chad , Kacinski Robert , Lang Amy 
Published: October 2020

Abstract
In this paper, we use a CFD analysis of a simplified, 2D geometry to study the ability of mako shark denticles to mitigate flow separation. We represent the viscous sublayer below a turbulent boundary layer streak as a Couette flow. Incipient separation is simulated by balancing upper wall velocity and adverse pressure gradient to achieve zero net mass flow, and we add various denticle geometries to study their effects. Each modeled denticle protrudes at an angle from 15° to 85° and sublayer blockage ratio from 0.05 to 0.85. Through variation of fluid properties and boundary conditions, we show that the anti-flow-reversal abilities of a single, bristled shark denticle are independent of Reynolds number, and we investigate the effect of the denticle at cases other than zero net mass flux. Based on these results, we create a new relationship to predict separation inhibition. These conclusions are highly generalizable and represent previously undiscovered universal behavior.
Effect of Heat Flux on Bubble Coalescence Phenomena and Sound Signatures During Pool Boiling
Authors: Negi Akshat , Rishi Aniket M. , Kandlikar Satish G. 
Published: October 2020

Abstract
Boiling heat transfer is extensively used in various industrial applications to efficiently dissipate a large amount of heat by maintaining lower surface temperatures. The maximum heat flux dissipated during boiling is limited by the critical heat flux (CHF) and limited visualization of the boiling surface limits the identification of the impending CHF condition to rely on temperature monitoring alone. The study presented here focuses on developing a method for analyzing and identifying acoustic signatures throughout the nucleate boiling regimes that are indicative of the boiling state of the heater surface. The bubble nucleation and coalescence along with bubble collapse at the liquid-vapor interface leads to variation in acoustic emission patterns during boiling. These sound waves are studied and acoustic signatures that are representative of the impending CHF are identified over plain and enhanced copper substrates with water as the working fluid. During pool boiling study, it was observed that sound was dominant in two frequency regions (400–500 Hz dominant throughout nucleate boiling and 100–200 Hz dominant at heat fluxes &gt; 100 W/cm2). However, just before CHF, a sudden drop in amplitude was observed in the high frequency region (400–500 Hz), while the amplitude in low frequency region (100–200 Hz) continued to rise. It was concluded that this acoustic study can be used as a tool to predict the approaching CHF condition.
An Experimental Study of R134a Condensation Heat Transfer in Horizontal Smooth and Enhanced Tubes
Authors: Guo Yu , Gu Zong-bao , Ayub Zahid , Li Wei , Ma Xiang , He Yan , Kukulka David J. 
Published: October 2020

Abstract
In this paper, the condensation heat transfer characteristics of R134a inside enhanced tubes using two type of surface structures with different materials was investigated, which were then compared with plain tubes under the same test conditions. The enhanced tubes were: 1EHTa tube with dimpled and petal arrays structure and 1EHTb tube with protrusion and similar petal arrays structure. The experiment was conducted for a mass flux ranging from 100 to 200 kg m−2 s−1 with saturation temperature of 318 K. The inlet and outlet vapor qualities were fixed at 0.8 and 0.2, respectively. The test tubes had the same outer diameter of 12.7 mm. Results showed that the dimpled and protruded surface tubes enhanced the convection condensation heat transfer and the heat transfer coefficient was 1.4 to 1.6 times higher than that of the smooth tube. Heat transfer enhancement of the 1EHTa and 1EHTb tube was mainly due to the complex roughness surface structures that created swirling and increased the interface turbulence. Enhanced tubes exhibited higher performance factors compared to the smooth tube. The average performance factor was 1.3–1.5. As the flow rate increases, there is no significant increase in the condensation heat transfer coefficient. The pressure drop penalty increased with mass flux. Compared with smooth tube, the pressure drop penalty of enhanced tube was larger.
Slip in the Presence of Semi-Circular Menisci Between Parallel Ridges
Authors: Steigerwalt Lam Lisa , Muzychka Yuri 
Published: October 2020

Abstract
Surfaces which are structured on the micro- and nanoscale to resist wetting are being considered for internal flows due to their drag reducing properties in applications such as electronics cooling and lab-on-chip. Here, an expression is developed to characterize the hydrodynamic slip in a laminar flow which occurs near the surface for the case when positive meniscus curvature is present. The surfaces considered are composed of ridges oriented parallel to the flow. Curvature of the meniscus, which resides between the liquid in the Cassie state and the gas trapped in cavities between the ridges, results from the pressure difference between the liquid and the gas. The meniscus is considered shear free. The no slip condition exists at the tips of the ridges. Conformal maps from the literature are used to derive an expression which is a function of cavity fraction of the surface. The positive protrusion angle is 90 degrees. Cavity fractions range from 0 to 75%.
A Comparative Analysis of the Tumor Pathology and the Metabolic Heat Generation of Growing Malignant Tumors
Authors: Owens Alyssa , Godbole Manasi , Dabydeen Donnette , Medeiros Lori , Phatak Pradyumna , Kandlikar Satish 
Published: October 2020

Abstract
Cancer is one of the most debilitating diseases in the world, affecting over 9.6 million people worldwide every year. Breast cancer remains the second largest cause of death in women. Despite major advances in treatment, over 40,920 women died of breast cancer in 2018 in the United States alone. Early detection of abnormal masses can be crucial for diagnosis and dramatically increase survival. Current screening techniques have varying accuracy and perform poorly when used on heterogeneously and extremely dense breast tissue. Infrared imaging has the potential to detect growing tumors within the breast based on thermal signatures on the breast surface by imaging temperature gradients induced by blood perfusion and tumor metabolic activity. Using clinical patient images, previous methods to estimate tumor properties involve an iterative algorithm to estimate the tumor position and diameter. The details from the MRI are used in estimating the volumetric heat generation rate. This is compared with the published values and the reasons for differences are investigated. The tumor pathology is used in estimating the expected growth rate and compared with the predicted values. The correlation between the tumor characteristics and heat generation rate is fundamental information that is needed in accurately predicting the tumor size and location.
Evaluating Multiple Domains of Health in High School Athletes With Sport-Related Concussion
Authors: Williams Richelle M. , Johnson Rachel S. , Snyder Valier Alison R. , Curtis Bay R. , Valovich McLeod Tamara C. 
Published: October 2020

Context: Concussions are shown to hinder multiple health dimensions, including health-related quality of life (HRQOL), suggesting a need for a whole-person approach to assessment and treatment. Patient-reported outcome measures are one method to gather the patient’s perspective regarding their HRQOL. Objective: To evaluate perceived HRQOL using the Patient-Reported Outcomes Measurement Information System Pediatric-25 subscale in patients throughout concussion recovery. Design: Prospective cohort, descriptive survey. Setting: There were 9 high school athletic training facilities. Participants: A total of 70 patients with diagnosed concussions (51 males, 7 females, 12 unreported; age = 15.7 [0.9] y, height = 174.6 [8.4] cm, mass = 72.8 [14.8] kg, grade = 10.0 [0.9] level). Interventions: Patient-Reported Outcomes Measurement Information System Pediatric-25 was administered at 3 days, 10 days postconcussion, and return to play (RTP). Main Outcome Measures: Patient-Reported Outcomes Measurement Information System Pediatric-25 subscale T scores and self-reported concussion history (yes/no). Results: A total of 70 patients completed the study. For the Pediatric-25 subscales, the severity of problems associated with Physical Function Mobility, Anxiety, Depression, Fatigue, and Pain Interference were highest 3 days postconcussion, decreasing at 10 days and RTP (all p < .05). No differences were found between days 3 and 10 for Peer Relationship scores, but improvements were identified at RTP (p < .05). Pediatric-25 subscale scores at the 3 measurements were not statistically associated with concussion history (all p > .05). Ceiling and floor effects were present in all subscales throughout each timepoint, except for Physical Function Mobility (14.7%), and pain interference (11.8%) at day 3 postinjury. Conclusions: Patients who had suffered a concussion improved from day 3 through RTP on multiple health domains as demonstrated through the Pediatric-25 subscales. These findings highlight the need for health care professionals to serially monitor HRQOL and social factors that may affect the patient postconcussion as part of a multifactorial assessment. Ceiling effects in high functioning adolescent athletes were present; thus, efforts should be made to identify appropriate scales for use in managing recovery in athletic populations.
Fragmentation of South China from greater India during the Rodinia-Gondwana transition
Authors: Wang Wei , Cawood Peter A. , Pandit Manoj K. , Xia Xiaoping , Raveggi Massimo , Zhao Junhong , Zheng Jianping , Qi Liang 
Published: October 2020

AbstractLate Tonian to Cambrian sedimentary sequences in northwestern India and South China provide vital evidence for modeling their paleogeographic linkage, including their juxtaposition and subsequent separation during the transition from the Rodinia to the Gondwana supercontinents. Similarities in lithostratigraphy and detrital zircon U-Pb-Hf-O isotopic characteristics in the late Tonian sedimentary units from both regions underline a common provenance. A substantial decrease in zircon δ18O values from super- to sub-mantle compositions and simultaneous increase in the zircon εHf(t) values in South China and northwestern India for the 800–700 Ma time window suggest a common Neoproterozoic extensional magmatic event, corresponding with the Rodinia breakup. A distinct change in sedimentary provenance is noted during the Cryogenian period. Sedimentation along the northwestern margin of India for the remainder of the Neoproterozoic encompasses large volumes of clastic detritus dominated by old zircon ages, derived inboard from the Indian craton. In contrast, contemporaneous sedimentary units in the Yangtze region of South China are dominated by Neoproterozoic zircons. The detrital zircon age data underline a close paleogeographic linkage between northwestern India and South China (Yangtze and Cathaysia regions) in the Rodinia supercontinent configuration and argue for their separation through continental rifting during the Cryogenian. Northwestern India developed into a passive margin, whereas the South China block partially rifted, rotated, and migrated dextrally along the Gondwana margin toward northeastern India and Western Australia, such that the Cathaysia block continued to receive detritus from Gondwana continental regions.
Epidemiology and risk factors for heat illness: 11 years of Heat Stress Monitoring Programme data from the FIVB Beach Volleyball World Tour
Authors: Racinais Sebastien , Alhammoud Marine , Nasir Nada , Bahr Roald 
Published: October 2020

ObjectivesTo analyse 11 years of FIVB heat stress-monitoring data to determine the relative influence of the different environmental parameters in increasing the likelihood of a heat-related medical time-out (MTOheat).MethodsA total of 8530 matches were recorded. The referee measured air temperature, black globe temperature, relative humidity and wet-bulb globe temperature (WBGT) before the matches, and registered the MTOheat. The absolute humidity was computed at posteriori.ResultsThere were 20 MTOheat cases, but only 3 resulted in forfeiting the match. MTOheat incidence was not statistically impacted by sex (p=0.59). MTOheat cases were more prevalent during the games played in Asia during the 4th quarter of the year (p<0.001). Two cases of MTOheat experienced diarrhoea or gastroenteritis during the 5 preceding days; both of them forfeited the match. A principal component analysis showed a specific environmental profile for the matches with MTOheat. They occurred at higher WBGT, temperatures and absolute humidity (p<0.001), but with a lower relative humidity (p=0.027).ConclusionsThe current data showed that an increase in ambient or black globe temperature, but not relative humidity, increased the risk of a MTOheat; but that the absolute risk remained low in elite beach volleyball players. However, suffering or recovering from a recent illness may represent a risk factor for a MTOheat to lead to player forfeit.
Assessing differential item functioning for the Social Appearance Anxiety Scale: a Scleroderma atient-centred Intervention Network (SPIN) Cohort Study
Authors: Sommer Sophia J , Harel Daphna , Kwakkenbos Linda , Carrier Marie-Eve , Gholizadeh Shadi , Gottesman Karen , Leite Catarina , Malcarne Vanessa L , Thombs Brett D 
Published: October 2020

ObjectivesThe Social Appearance Anxiety Scale (SAAS) is a 16-item questionnaire developed to evaluate fear of appearance-based evaluation by others. The primary objective of this research was to investigate the existence of differential item functioning (DIF) for the 16 SAAS items, comparing patients who completed the SAAS in English and French, either to confirm that scores are comparable or provide guidance on calculating comparable scores. A secondary research objective was to investigate the existence of DIF based on sex and disease status. A tertiary research objective was to assess DIF related to language, sex, and disease status on the recently developed SAAS-5.DesignThis was a cross-sectional analysis using baseline data from patients enrolled in the Scleroderma Patient-centred Intervention Network (SPIN).SettingSPIN patients included in the present study were enrolled at 43 centres in Canada, USA, UK, France and Australia, with questionnaires completed in April 2014 to July 2019.Participants1640 SPIN patients completed the SAAS in French (n=600) or English (n=1040).Primary and secondary measuresThe SAAS was collected along with demographic and disease characteristics.ResultsSix items were identified with statistically significant language-based DIF, four with sex-based DIF and one with disease type-based DIF. However, factor scores before and after accounting for DIF were similar (Pearson correlation >0.99), and individual score differences were small. This was true for both the full and shortened versions of the SAAS.ConclusionSAAS and SAAS-5 scores are comparable across language, sex, and disease-type, despite small differences in how patients respond to some items.