bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Reynolds Number, Mudflap Configuration and Loading Shape on the Wake of an Earthmoving Dump Truck: A Wind Tunnel Study
Authors: Obeid Bachar , Durán García Edwin , Murzyn Frédéric , Muresan-Paslaru Bogdan , Razakamanantsoa Andry 
Published: September 2024

Abstract
Heavy-duty dump trucks are an important source of particle emissions. When traveling on unpaved roads, they emit particles through wear and resuspension mechanisms. The particles are then dispersed by the turbulence created in the vehicle wake, leading to a deterioration of air quality in and around construction sites. A better understanding of the truck’s wake flow dynamics is therefore required to get a better knowledge of the resuspended particle dynamics. In the present work, the effects of Reynolds number, mudflap configuration, and load shape on the wake flow topology of an earthmoving dump truck are experimentally investigated in a wind tunnel study. 2D LDV measurements are conducted in the wake of a reduced-scale (1:50) dump truck. Three different velocities are studied (8, 12, and 16 m/s), corresponding to a height-based Reynolds number (Reh) ranging from 36,216 to 72,432. Additionally, three configurations of mudflaps (without a mudflap, a single long mudflap, and two mudflaps behind the wheels) and three shapes of material loading (empty dumpster, flat load, and dome-shaped overload) are considered. The results show that the presence of a long mudflap results in the formation of a large vortex in the truck’s wake, which is supposed to increase particle emissions. The shape of the load also plays a key role. The dome-shaped overload increases the size of the vortices and the upward backflow that develop in the close wake of the vehicle, thus enhancing particle emission. Finally, a quadrant analysis of Reynolds shear stress shows that the long mudflap favors the appearance of sweep events in the upper shear layer and close to the ground, which is supposed to increase particle emissions.
New Theoretical Shock Loss Model for Axial Fans Based on the Integral Momentum Equation
Authors: Fritsche Manuel , Epple Philipp 
Published: September 2024

Abstract
To analyze the pressure characteristic behavior of axial fans during the design process, an analytical estimation of the pressure characteristic is of interest for industry and academia. The loss models for turbomachines are traditionally based on the energy equation, i.e. the Bernoulli equation, in combination with loss coefficient. Different than the energy conservation equation, the integral momentum equation can deliver the pressure loss term without any empirical loss coefficient.
In the present contribution, this issue has been addressed and the authors developed a new combined loss model especially for axial fans consisting of a slip factor model and a shock loss model. With the integral momentum approach, no empirical constants are needed for the shock loss model, in contrast to the energy equation-based models. In this work it is shown on the example of axial fan losses, that the integral momentum equation is a powerful method to estimate losses. This approach can also be extended to other applications and can be included on a broader basis in the classes of fluid mechanics and turbomachinery in the engineering education.
For validation, several axial fans have been computed with CFD using the commercial solver ANSYS CFX 2023 and compared with the theoretical characteristics computed with the Euler turbomachinery equation in combination with the new combined loss model of the authors. The comparison of the theoretical predictions based on the integral momentum equation and the numerical computations are in very good agreement, showing that the theoretical loss model produces very reliable results and full axial fan characteristics.
Influence of Monovalent and Divalent Salts on Oil-Water Emulsion Stabilized by Nonionic Surfactants
Authors: Alanazi Khalid , Mohan Ram , Kolla Srinivas Swaroop , Shoham Ovadia 
Published: September 2024

Abstract
It is still unclear how the presence of certain ions influences nonionic surfactant-stabilized emulsions. Hence, the purpose of this work is to investigate the effect of monovalent (NaCl) and divalent (CaCl2) ions on an oil-water emulsion stabilized by two different nonionic surfactants, Tergitol 15-S-7 (T15S7) and Span® 80 (SP80). Emulsions were formed in a 60 mm gravity-based separator of a nominal volume of 200 ml. In addition to a wide range of ion concentration, the study looked at the effect of low (800 RPM) and high (2500 RPM) mixing speeds at water-to-oil ratios (WORs) of 1:3 and 3:1. At low mixing speeds and WORs, experimental results showed that the presence of ion (regardless of its concentration or type) does not affect emulsions stabilized by SP80. However, when mixed at higher speeds, ions were shown to increase the volume of the same system. Data of SP80-stabilized emulsions also showed that the increase of WOR from 1:3 to 3:1 causes a significant drop in the volume of the emulsion regardless of ion type and/or concentration. On the contrary, at a WOR of 1:3, the presence of ions was shown to reduce the volume of T1S57-stabilized emulsions. However, although mixed at two different speeds, the separation kinetics of T15S7-stabilized emulsions became salt-independent after a few hours of formation.
Development of a Diffuser Type Multistage Pump With Low Specific Speed
Authors: Kim Joshua Joohyen , Kim Dohong , Kim Hyeonsig , Boehle Martin 
Published: September 2024

Abstract
Multistage pumps delivering small flow-rate at very high-head are used for fertilizer, chemical, oil production, and power plant. Low specific speed (nq) pumps often show insufficient head-rise to zero-flow, unstable head-curve, and low efficiency. The current study presents a development procedure of hydraulic components for a diffuser-type multistage pump at nq = 12.9 [m3/s, m, rpm] and test results of 4-stage pump. Various design methods were applied to the new impeller and diffuser to increase shut-off head such as an extended-cut leading-edge, tight gap of between impeller and diffuser side plates and so on. The measured head-curve was stable with a head-rise ratio over 1.2 from BEP to shut-off. CFD simulation results showed that the kinetic energy of fluid could not be sufficiently converted into the potential energy in the guide-vane channels due to the compact construction of the low nq pump. A continuous diffuser consisting of guide-vanes, cross-over channels, and return-vanes was designed and optimized based on flow-quality analysis to achieve a high efficiency and flat efficiency-curve near BEP. Two types of seal patterns, rectangular grooves and plain, were applied on the front wear-ring and balance drum. The measurement outputs were compared and the impact of leakage on pump performance at the low nq were discussed.
Physics-Based Design and Optimization Strategy for Low-Pressure Axial Fans
Authors: Fritsche Manuel , Epple Philipp 
Published: September 2024

Abstract
For cost and manufacturing reasons, low-pressure axial fans are typically manufactured with three-dimensionally curved sheet metal blades of constant thickness. However, the design method for low-pressure axial fans presented in this work is also suited for the design of axial fans with thin blades. In addition, there is an increasing demand for a free shaped hub geometry, for example a conical hub contour.
In the extended design strategy, the concept of the radial equilibrium is applied under the specification of a blade work distribution in the form of a design total pressure distribution in the radial direction on five partial flow sections. In addition, the radial equilibrium and the specified design total pressure distribution are also specified on five sections in the axial direction along the blade. This method is based on the application of pure analytical physics-based equations, which are solved on each partial flow section in the radial and axial direction and allows a detailed design of the blade geometry.
Furthermore, the presented analytical extended design strategy has been optimized using statistical methods. This has been performed with ANSYS CFX 2023 and the ANSYS Workbench. For this purpose, a meta-model-based optimization strategy for the designed blade angles is proposed. The iterative application of the indirect optimization process, consisting of a DOE analysis, a response surface method (RSM) and a subsequent multi-objective optimization on the axial section in the direction of flow is efficient and effective.
Finally, the extended design and optimization strategy has been applied and verified with numerical and experimental data. The comparison of the characteristics of the measurement data with the numerical CFD results showed a very good agreement and the accuracy and reliability of the developed CFD model have been validated.
A Numerical Investigation of the Longitudinal Vortex Pair Structure in Underbody Diffuser Flows
Authors: Mayoral Salvador , Massis Anthony 
Published: September 2024

Abstract
An automotive diffuser is an open channel within the under-body of a vehicle that features a diverging ramp in the aft section. The performance of a diffuser is sensitive to ground effect where decreases in ride height result in increases in downforce. However, below a critical value, any further reduction in ride height results in a significant loss of downforce. Previous experimental investigations demonstrated that the dominant flow feature within underbody diffuser flows is a pair of counter-rotating longitudinal vortices, and the resulting downforce behavior is directly linked to the structure of the longitudinal vortex pair. This study investigates the effect of ride height on the behavior of the longitudinal vortex pair within an underbody diffuser flow in ground effect. The unsteady flow past a diffuser-equipped bluff body with a 17° diffuser ramp angle is simulated using large eddy simulation with wall-stress modeling, commonly referred to as wall modeled large eddy simulation (WMLES). The flow Reynolds number based on body length is 1.75 × 106. Numerical simulations are performed with OpenFOAM and WMLES is implemented with libWallModelledLES, a third-party WMLES library for OpenFOAM. Results show that the mean center-line surface pressure distributions along the underbody match well with experiments. Visualization of the vortices with isosurfaces of the Q-criterion demonstrates that the longitudinal vortices experience a spiral-type vortex breakdown which propagates upstream with decreasing ride height.
Analysis of Flow Field Under Unsteady Breathing Conditions in a Realistic Human Nasal Cavity
Authors: Shahed Syeda Reham , Tian Lin , Dong Jingliang , Tu Jiyuan , Zhang Ya , Ma Ruiping , Ahmadi Goodarz 
Published: September 2024

Abstract
The human nasal airway is a complex structure that provides the first line of defense to filter foreign particles before reaching the lungs. With the increased occurrence of nasal and nasopharyngeal cancers, understanding nasal airflow dynamics is crucial to assessing the potential airflow-related causes. Although human respiration is inherently unsteady, many earlier studies have been conducted for an effective steady breathing state. In this study, we analyzed unsteady respiration in a realistic human nasal cavity using the Ansys-Fluent software. A sinusoidal inhalation and exhalation at peak breathing of 10 1/min was simulated. It was found that the inhalation and exhalation breathing show different airflow dynamics. In particular, significant reversed flow conditions were observed at the entrance to the main nasal cavity from the pharynx during the exhalation phase. Both inhalation and exhalation exhibit significant acceleration and deceleration phases, with more prominent vortices forming during the deceleration phase of the inhalation period. Particular attention was given to the unsteady airflow condition in turbinate and olfactory regions. Our study showed that transient breathing in the nasal cavity and its impact on particle deposition needs further investigation.
Computational Studies on Droplet Dynamics in Microtubes With Rough Surface via Spectral Elements
Authors: Melbye Julie , Wang Yechun 
Published: September 2024

Abstract
A plethora of studies have investigated the motion of liquid droplets in microtubes or microchannels as technologies in microfluidics developed rapidly in recent decades. Most computational studies on this topic assumed smooth inner surface for the fluid conduit. However, there are few studies that consider the roughness of the inner surface that could affect the droplet motion, especially for the cases in which the roughness size is comparable to that of the droplet. In this study, we employ a 3D spectral boundary element method for interfacial dynamics to examine the droplet translation, migration, and deformation in a micron-sized cylindrical tube with a rough inner surface. The roughness feature of the surface is comparable to the size of the droplet and is simulated with sinusoidal functions. The computational results show that the surface roughness significantly affects the behavior of a deformable droplet, including its deformation as well as the speed of translation. The results of this study could provide contribution to the development of microfluidics.
Characteristics of Turbulent Flow Around Right-Trapezoidal Prisms With Varying Upper and Lower Lengths
Authors: Guney Aleyna , Abdul-Salam Fati Bio , Sagharichi Amir , Tachie Mark F. 
Published: September 2024

Abstract
The turbulent characteristics of flow separation induced by trapezoidal prisms subjected to uniform flow are studied using particle image velocimetry (PIV). The streamwise aspect ratios (upper length to lower length) were AR1.0_2.5, AR2.0_2.5, and AR2.0_4.0. The Reynolds number (based on freestream velocity and body height) was Reh = 10000 and the results were analyzed in terms of the mean velocities, Reynolds stresses, and proper orthogonal decomposition. Recirculation bubbles formed in the wake region are asymmetric about the prism centerline, and the lower bubble is smaller than the upper one. Contours of the streamwise Reynolds normal stress exhibit two peaks in the wake of the prisms, and an additional peak over the upper surface of the prism. The peak magnitude of streamwise Reynolds normal stress in the upper and lower wake region are identical. A single peak in the vertical Reynolds normal stress is observed near the centerline of the prism within the wake region. Proper orthogonal decomposition was used to characterize the energetic vortical structures of the flow field around the prisms. The results show that the first two POD modes capture similar relative energy content, regardless of aspect ratio, while the wavelength of the POD decreases as the aspect ratio increases.
Computational Study of Noise Control of Different Sound Reducing Materials Surrounding Wind-Tunnels
Authors: Si Xiuhua , Bartlett Gabriel , Xi Jinxiang 
Published: September 2024

Abstract
Wind tunnels are frequently utilized in aerospace industries and universities for research, design, or demonstration purposes. However, they can generate high volumes of noise, especially at high wind speeds, posing acoustic hazards to those nearby. Thus, minimizing noise generation from wind tunnels is paramount, especially when the wind tunnel is located within a building shared by many others. Considering that sound generation can be attributed to structural vibroacoustics and flow aeroacoustics, this study aimed to design an effective sound reduction insert using varying materials to reduce noise generation in a newly developed wind tunnel at CBU. In addition to theoretical analyses, COMSOL simulations were conducted to design and optimize the shape, size, and material of the sound-dampening insert. Several materials were selected for their acoustic transmission properties and were systematically tested in wind tunnel settings by varying their thicknesses, shapes, and combinations with other materials. Aeroacoustics simulations demonstrated that the optimal material for sound dampening is gypsum board, with a trapezoidal shape, and a backbone of plywood material.
Techno-Economic Assessment of Urban Wind Energy Near Various Common Building Configurations
Authors: Mortazavian Javad , Goudarzi Navid 
Published: September 2024

Abstract
Urban wind energy has become a popular source of sustainable power in modern urban configurations. This study aims to analyze the technical and economic aspects of installing wind-harnessing devices near different common urban configurations. Computational fluid dynamics simulations utilized by Reynolds-Averaged Navier-Stokes equations and realizable k-ϵ turbulence model are used to model the turbulent urban canopy layer in the vicinity of four different urban settings namely an isolated high-rise building model, and 3 clusters of buildings with different central building heights, ranging from no building to a high-rise building model. Normalized wind power density (PD) and turbulence intensity (TI) contours were plotted to identify areas of interest to install urban wind turbines. To show the significance of this research, the levelized cost of energy was calculated for an urban horizontal axis wind turbine installed at locations with the highest wind PD and lowest TI values. The results indicated that while the highest wind PD locations and their values change with the selected configuration, promising regions can be identified for wind harnessing applications.
The Efficacy of Ischemic Preconditioning on Handgrip Strength and Strength Endurance in Para-Athletes With Spinal-Cord Injury: A Pilot Study
Authors: Kasofsky Lexi , Cross Rebecca , Tavoian Dallin , Siegler Jason 
Published: September 2024

Purpose: This pilot study investigated the functional outcomes after ischemic preconditioning (IPC) in high-level para-athletes with spinal-cord injury. Methods: Nine athletes completed 2 handgrip exercise trials (an isometric hold to failure at 60% maximal voluntary contraction [ISO] and a progressive, intermittent handgrip to failure [INT]), preceded by either IPC (220 mm Hg) or sham (20 mm Hg) for six 5-minute periods, in a repeated-measures, crossover design. Results: Although small performance improvements in time to task failure were observed in the ISO (∼5%) and INT (∼8%) IPC conditions, which are similar to those reported elsewhere, no statistical influence was observed (ISO–IPC, 74.2 [32.6] s; SHAM, 70.7 [27.2] s; P = .73; INT–IPC, 426.0 [80.1] s; SHAM, 392.2 [42.5] s; P = .35). Fatigue was evident in the forearm muscle force (maximal voluntary contraction) ISO (mean decline of 178.1 [76.0] N [95% CI, −10.4 to 366.7 N]; P < .05) and INT (mean decline of 182.2 [72.5] N [95% CI, 34.5–329.8 N]; P < .05) trials but not different between treatments (P > .95). Conclusions: Although small performance improvements in time to task failure were observed, the findings of the present data set suggest that acute bouts of IPC do not meaningfully influence fatigue during handgrip exercise in para-athletes with spinal-cord injury.
Synergistic antimicrobial combination of third-generation cephalosporins and polymyxin B against carbapenem-polymyxin-resistant
Klebsiella pneumoniae:
an
in vitro
and
in vivo
analysis
Authors: Sturaro Mariana Carvalho , Damaceno Nathalia da Silva , Faccin Izadora Dillis , Silva Osmar Nascimento , de Aquino Thiago Mendonça , Freire Nathalia Monteiro Lins , Alcântara Marcone Gomes dos Santos , Monteiro Kadja Luana Chagas , Rossato Luana , de Souza Gleyce Hellen de Almeida , Simionatto Simone 
Published: September 2024

ABSTRACT

Antibiotic combination therapy is a promising approach to address the urgent need for novel treatment options for infections caused by carbapenem-polymyxin-resistant
Klebsiella pneumoniae
(CPR-Kp). The present study aimed to investigate the synergistic potential of four cephalosporins in combination with polymyxin B (PMB). A checkerboard assay was performed to evaluate the synergistic effects of cephalexin (CLX), cefixime, cefotaxime (CTX), and cefmenoxime (CMX) in combination with PMB. Subsequently, experiments evaluating the use of CTX or CMX in combination with PMB (CTX-PMB or CMX-PMB, respectively), including growth curve and SynergyFinder analysis, antibiofilm activity assays, cell membrane integrity assays, and scanning electron microscopy, were performed. Safety assessments were also conducted, including hemolysis and toxicity evaluations, using
Caenorhabditis elegans
. Furthermore, an
in vivo
model in
C. elegans
was adopted to assess the treatment efficacy against CPR-Kp infections. CTX-PMB and CMX-PMB exhibited low fractional inhibitory concentration indexes ranging from 0.19 to 0.50 and from 0.25 to 1.5, respectively, and zero interaction potency scores of 37.484 and 15.076, respectively. The two combinations significantly reduced growth and biofilm formation in CPR-Kp. Neither CTX-PMB nor CMX-PMB compromised bacterial cell integrity. Safety assessments revealed a low hemolysis percentage and high survival rates in the
C. elegans
toxicity evaluations. The
in vivo
model revealed that the CTX-PMB and CMX-PMB treatments improved the survival rates of
C. elegans
. The synergistic effects of the CTX-PMB and CMX-PMB combinations, both
in vitro
and
in vivo
, indicate that these antibiotic pairings could represent effective therapeutic options for infections caused by CPR-Kp.
The class III phosphatidylinositol 3-kinase VPS34 supports EV71 replication by promoting viral replication organelle formation
Authors: Wu Bo , Fan Tingting , Chen Xinrui , He Yingli , Wang Hongliang 
Published: September 2024

ABSTRACT

Enterovirus 71 (EV71) belongs to the family of
Picornaviridae
; it could cause a variety of illnesses and pose a great threat to public health worldwide. Currently, there is no specific drug treatment for this virus, and a better understanding of virus-host interaction is crucial for novel antiviral development. Here, we find that the class III phosphatidylinositol 3-kinase, VPS34, is an essential host factor for EV71 infection. VPS34 inhibition with either shRNA or specific chemical inhibitor significantly reduces EV71 infection. Meanwhile, EV71 infection upregulates phosphatidylinositol 3-phosphate (PI3P) production in viral replication organelles (ROs), while the depletion of PI3P by phosphatase overexpression inhibits EV71 infection. In addition, the PI3P-binding protein, double FYVE-containing protein 1 (DFCP1), is also required for an efficient replication of EV71. DFCP1 could interact with viral 2C protein and facilitate viral association with lipid droplets (LDs), which are important lipid sources for viral RO biogenesis. Taken together, these results indicate that EV71 virus exploits the VPS34-PI3P-DFCP1-LDs pathway to promote viral RO formation and viral infection, and they also illuminate novel targets for antiviral development.

IMPORTANCE
Enterovirus 71 (EV71) is a major pathogen that causes hand-foot-and-mouth disease (HFMD) and other serious complications, which are big threats to children under 5 years old. Unravelling the interactions between virus and the host cells will open new avenues in antiviral research. Here, we found the class III phosphatidylinositol 3-kinase, VPS34, and its effector, double FYVE-containing protein 1 (DFCP1), were essential for EV71 infection, both of which could support EV71 viral replication by enhancing the biogenesis of viral replication organelles (ROs). As DFCP1 localizes to lipid droplets, hijacking of these host factors will enable viral utilization of lipids from LDs for the generation of membrane structures during RO biogenesis. In addition, the VPS34 kinase inhibitor was found to be potent against EV71 infection; therefore, this study also brings up a novel target for future anti-EV71 drug development.