bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhancing phosphorus availability, soil organic carbon, maize productivity and farm profitability through biochar and organic–inorganic fertilizers in an irrigated maize agroecosystem under semi‐arid climate
Authors: Arif Muhammad , Ali Salman , Ilyas Muhammad , Riaz Muhammad , Akhtar Kashif , Ali Kawsar , Adnan Muhammad , Fahad Shah , Khan Imran , Shah Shahen , Wang Haiyan 
Published: October 2020

AbstractBiochar amendments offer promising potential to improve soil fertility, soil organic carbon (SOC) and crop yields; however, a limited research has explored these benefits of biochar in the arid and semi‐arid regions. This two‐year field study investigated the effects of Acacia tree biomass‐derived biochar, applied at 0 and 10 t ha‒1 rates with farmyard manure (FYM) or poultry manure (PM) and mineral phosphorus (P) fertilizer combinations (100 kg P ha‐1), on maize (Zea mays L.) productivity, P use efficiency (PUE) and farm profitability. The application of biochar with organic–inorganic P fertilizers significantly increased soil P and SOC contents than the sole organic or inorganic P fertilizers. Addition of biochar and PM as 100% P source resulted in the highest soil P (104% increase over control) and SOC contents (203% higher than control). However, maize productivity and PUE were significantly higher under balanced P fertilizer (50% organic + 50% mineral fertilizer) with biochar and the increase was 110%, 94% and 170% than 100%‐FYM, 100%‐PM and 100% mineral fertilizer, respectively. Maize productivity and yield correlated significantly positively with soil P and SOC contents These positive effects were possibly due to the ability of biochar to improve soil properties, P availability from organic–inorganic fertilizers and SOC which resulted in higher PUE and maize productivity. Despite the significant positive relationship of PUE with net economic returns, biochar incorporation with PM and mineral fertilizer combination was economically profitable, whereas FYM along biochar was not profitable due to short duration of the field experiments.
A Robust Design Perspective on Factors Influencing Geometric Quality in Metal Additive Manufacturing
Authors: Ramesh Sagar Vaishak , Lorin Samuel , Wärmefjord Kristina , Söderberg Rikard 
Published: October 2020

Abstract
Additive manufacturing (AM) for metals is a widely researched, continuously enhanced manufacturing process and is implemented across various industries. However, the AM process exhibits variation that affects the geometric quality of the end product. The effect of process variation on geometric quality is rarely considered during the design stages. In this paper, sources that influence the geometric quality in a metal AM process are reviewed from a robust design perspective and further sorted into control factors and noise factors. A framework for geometric robustness analysis of AM products is presented as an outcome. This framework would facilitate development of methods and tools to produce geometry assured AM products. Also, the prospects of variation simulation to support geometric robustness analysis and the challenges associated with it are discussed.
Turbulence Modeling Using Z-F, RSM, LES and WMLES for Flow Analysis in Z-Shape Ducts
Authors: Karbon Mohammed , Sleiti Ahmad K. 
Published: October 2020

Abstract
Turbulent flow in Z-shape duct configuration is investigated and analyzed using Reynolds Stress Model (RSM), Large Eddy Simulation (LES), ζ-f Model, and Wall-Modeled Large Eddy Simulation (WMLES). The results are validated and compared to experimental data. Both RSM and ζ-f models are based on steady-state RANS solutions, while LES and WMLES models account for temporal variations transient behavior of the flow turbulence. The focus was on regions where RSM has over or under predicted the flow and regions where there are flow separations and high turbulence. LES simulation results have shown under-prediction and over-prediction in the flow separation and re-attachment regions. It is found that the turbulent kinetic energy production in ζ equation is much easier to reproduce accurately than other models. Both mean velocity gradient and local turbulent stress terms are also much easier to resolve properly. The current research has found that ζ-f model not only takes less time to complete the simulation but also the mean flow velocity profile results are in better agreement with experimental data than RSM model despite both are coupled steady-state RANS. ζ-f model numerically resolved both the flow separation and re-attachment regions better than RSM model. WMLES model is employed to investigate the SGS model impact on the small eddies dissipated from the large eddies. Such WMLES model produces much better results than the LES model, however the SGS viscosity damps the energy of the flow.
Modeling Non-Spherical Particulate Systems in the DEM Framework
Authors: Srinivasan Vivek , Tafti Danesh 
Published: October 2020

Abstract
Particulate systems in practical applications have mostly been represented using spherical shapes, even though the majority of particles in archetypal fluid-solid systems are non-spherical. Modeling dense fluid-particulate systems using non-spherical particles involves increased complexity, with computational cost manifesting as the biggest bottleneck.
In this research, a novel Discrete Element Method (DEM) model that incorporates geometry definition, collision detection, and post-collision kinematics has been developed to accurately simulate non-spherical particulate systems. Superellipsoids, which account for 80% of particles commonly found in nature, are used to represent non-spherical shapes. Collisions between these particles are processed using a hierarchical detection method. An event-driven model and a time-driven model have been employed in the current framework to resolve collisions. The collision model’s influence on non-spherical particle dynamics is verified by observing the conservation of momentum and total kinetic energy. Furthermore, the non-spherical DEM model is coupled with an in-house fluid flow solver (GenIDLEST). The combined CFDDEM model results are validated by comparing to experimental measurements in a fluidized bed. The parallel scalability of the non-spherical DEM model is evaluated in terms of its efficiency and speedup. Major factors affecting wall clock time of simulations are analyzed and an estimate of the model’s dependency on these factors is given.
Improved DRW Model for Prediction of Deposition and Dispersion of Nano- and Micro-Particles in Turbulent Flows
Authors: Mofakham Amir A. , Ahmadi Goodarz 
Published: October 2020

Abstract
In this study, the accuracy of the discrete random walk (DRW) stochastic model in generating the instantaneous velocity fluctuations as seen by micro- and nano-particles in inhomogeneous turbulent flows were examined. Particular attention was given to the effects of the non-uniform normal RMS velocity fluctuations and turbulence time scale on the DRW model predictions. The trajectories of randomly injected point-particles with diameters ranging from 10 nm to 30 μm in a duct were evaluated using an in-house Matlab particle tracking code. The particle equation of motion included the drag and Brownian forces. The fully developed mean velocity and RMS fluctuation velocity profiles were exported from the RANS (v2f) simulations and were used for the particle dispersion and transport analysis. It was assumed that the particle-laden flow is sufficiently dilute so that the particle-particle collisions and the two-way coupling effects of particles on the flow could be ignored.
To incorporate the instantaneous turbulence velocity fluctuations effects on particle dispersion, the Conventional-DRW model (in the absence of drift corrections), which was originally developed for homogenous turbulent flows, was first used. It was shown that the Conventional-DRW model leads to superfluous migration of fluid-point particles toward the wall and erroneous particle deposition rate. The Modified-DRW model with an appropriate velocity gradient drift correction term was also tested. It was found that the predicted concentration profiles of tracer particles still are not uniform. It was hypothesized that the reason for this erroneous prediction is due to the inhomogeneous turbulence time macroscale in the channel flow. A new drift correction term as a function of gradients of both RMS fluctuation velocity and the turbulence time macroscale was proposed. It was shown that the new Improved-DRW model with the velocity and time scale drift corrections leads to uniform distributions for fluid-point particles and reasonable concentration profiles for finite-size particles. It was shown that the predicted deposition velocities of different size particles by the proposed Improved-DRW model are in good agreement with the available experimental data as well as the predictions of the empirical models and earlier DNS results.
Computational Analysis of Fiber Dynamics in Human Nasal Cavity
Authors: Ma Jiawei , Tu Jiyuan , Tian Lin , Ahmadi Goodarz 
Published: October 2020

Abstract
Elongated particles, such as asbestos and mineral fibers, are considered severe inhalation hazards due to their ability to penetrate into the deep lung. Frequently the dynamic behavior of the fibrous particles is attributed to their unique needle-like geometry. Therefore, understanding the interactions of the inhaled elongated particles with the airflow environment is of great significance. In this study, the transport and deposition of elongated micro-fibers in a realistic human nasal cavity is investigated numerically. The motion of the micro-fiber is resolved by solving the system of equations governing its coupled translational and rotational motions. The governing equations included the drag, the hydrodynamic torques that were evaluated using the Jeffrey model. The influence of the shear lift force was also included in these simulations. The no-slip wall boundary condition for airflow in the airways was used. Since the surface of airways is covered with mucus, when a fiber touches the surface, it was assumed to be deposited with no rebound. The study allows a close look at the non-spherical particle-flow dynamics with respect to the translation, rotation, coupling, and how the rotation affects the particle’s macroscopic transport and deposition properties. A series of simulations for different microfiber diameters and aspect ratios were performed. The simulation results are compared with the existing experimental data, and earlier computational model predictions and good agreements were obtained. The present study also seeks to provide additional insight into the transport processes of microfibers in the upper respiratory tract.
Performance of Francis Turbine Operating at Excess Load Condition
Authors: Altimemy Muhannad , Caspar Justin , Oztekin Alparslan 
Published: October 2020

Abstract
Computational fluid dynamics simulations are conducted to characterize the spatial and temporal characteristics of the flow field inside a Francis turbine operating in the excess load regime. A high-fidelity Large Eddy Simulation (LES) turbulence model is applied to investigate the flow-induced pressure fluctuations in the draft tube of a Francis Turbine. Probes placed alongside the wall and in the center of the draft tube measure the pressure signal in the draft tube, the pressure over the turbine blades, and the power generated to compare against previous studies featuring design point and partial load operating conditions. The excess load is seen during Francis turbines in order to satisfy a spike in the electrical demand. By characterizing the flow field during these conditions, we can find potential problems with running the turbine at excess load and inspire future studies regarding mitigation methods. Our studies found a robust low-pressure region on the edges of turbine blades, which could cause cavitation in the runner region, which would extend through the draft tube, and high magnitude of pressure fluctuations were observed in the center of the draft tube.
Application of FMI in Metal Casting Press-Forming Process
Authors: Xingli Zhong , Linhong Ji , Sheng Li , Yijia Lu 
Published: October 2020

Abstract
Accurate simulation of metal casting press-forming process needs to consider mutual coupling effects in a number of different fields of physics subsystem. Hydraulic systems, control systems and mechanical systems are the most important subsystems among them. It is difficult to create various subsystems in detail in a single modeling tools, so co-simulation technology is used to take advantage of different tools to achieve the entire physical process of system-level simulation. The paper researched the co-simulation in the Abaqus software and the Matlab software based on FMI standard, considered fully the coupling effect between different systems, and simulated the metal casting press-forming process. The simulation results showed that co-simulation based on FMI standard can be well suited for multi-disciplinary co-simulation in complex mechanical model, and played a well-guiding role in the engineering design. The co-simulation would take more computation time than traditional simulation, but it can be achieved to research the integrated features of system and to reduce greatly experiments costs and prototype trial risks by using this technology.
Micro Machined Slit Between Ridge and Groove in Micro Fluid-Channel to Measure Floating Cell Deformability
Authors: Hashimoto Shigehiro 
Published: October 2020

Abstract
A micro-slit has been designed to measure deformation of a biological single cell passing through the slit. At the middle part of the flow channel, the slit (7 μm height, 0.4 mm width, and 0.1 mm length) has been made by photolithography technique: the combination of the micro-ridge on the transparent polydimethylsiloxane plate and the micro-groove on the glass plate. C2C12 (mouse myoblast cells) was used in the test. The flow of suspension of cells was controlled by the pressure head between the inlet and the outlet. Deformation of cells passing through the micro slit was observed with an inverted phase-contrast microscope. The experimental results show that a cell deforms to the flat circular disk and passes through the micro-slit. Although smaller cells tend to pass the micro-slit easily, some bigger cells also passed the micro-slit. Deformation ratio is independent of the size of each cell. The designed slit has capability to detect quantitative deformability of a single biological cell.
Simulation on Flow Pattern Transition With Liquid Nitrogen and its Vapor Using a Droplet Entrainment Model
Authors: Zhou Rui , Xia Tao , Zhang Xiaobin 
Published: October 2020

Abstract
A droplet entrainment model was applied to characterize the flow pattern transition in the countercurrent horizontal flow with liquid nitrogen (LN2) and vapor nitrogen (VN2). A two-fluid three-field model consisting of liquid film, gas, and droplet was implemented based on the Eulerian-Eulerian model in ANSYS Fluent®. In the droplet entrainment model, the condition and position of the droplet generation were realized by calculating the velocity gradient in the normal direction of the interface towards the gas core. The droplet entrainment and deposition rates were also included and validated according to the available data of water/air in the literature. Three flow patterns, including stratified-wavy flow, churn flow, and pseudo-slug flow, were identified in simulation results with LN2/VN2. Furthermore, ligament breakup was found to be the main droplet entrainment mechanism in the churn and pseudo-slug flow, and there can be a high probability of the occurrence of bubble burst as well. Compared with water/air, the droplets are more easily to be entrained in LN2/VN2 due to the smaller viscosity and surface tension according to the results of droplet mass flow rate. Pressure drop signals of the three flow patterns were also obtained and analyzed.
A Comparative Numerical Study on Two-Phase Boiling Fluid Flow and Heat Transfer in the Microchannel Heat Sink With Different Manifold Arrangements
Authors: Luo Yang , Zhang Jingzhi , Li Wei 
Published: October 2020

Abstract
The manifold microchannel (MMC) heat sink system has been widely used in high-heat-flux chip thermal management due to its high surface-to-volume ratio. Two-phase, three-dimensional numerical methods for subcooled flow boiling have been developed using a self-programming solver based on OpenFOAM. Four different types of manifold arrangements (Z-type, C-type, H-type and U-type) have been investigated at a fixed operational condition. The numerical results evaluate the effects of flow maldistribution caused by different manifold configurations. Before simulating the two-phase boiling flow in MIMC metamodels, single-phase liquid flow fields are performed at first to compare the flow maldistribution in microchannels. It can be concluded from the flow patterns that H-type and U-type manifolds provide a more even and a lower microchannel void fraction, which is conducive to improving the temperature uniformity and decreasing the effective thermal resistance. The simulation results also show that the wall temperature difference of H-type (0.471 K) is only about 10% of the Z-type (4.683 K). In addition, the U-type manifold configuration show the lowest average pressure drop at the inlet and outlet of the MIMC metamodel domain. However, H-type manifold also shows an impressive 59.9% decrease in pressure loss. Results indicate that both the H-type and the U-type manifolds for flow boiling in microchannels are recommended due to their better heat transfer performance and lower pressure drop when compared with Z-type and C-type.
Oblique Micro Grooves on Bottom Wall of Flow Channel to Sort Cells
Authors: Hashimoto Shigehiro 
Published: October 2020

Abstract
The movement of a flowing cell near the oblique micro groove on the bottom surface in the micro flow channel has been measured to sort biological cells in vitro. The micro groove of the rectangular shape (4.5 μm depth, and 0.2 mm length) was fabricated on the polydimethylsiloxane (PDMS) disk by the photolithography technique. The angle between the flow direction and the longitudinal axis of the groove is 45 degree. Variation has been made on the width (0.03 mm &lt; w &lt; 0.05 mm) of the groove. A rectangular flow channel (0.05 mm height × 1 mm width × 25 mm length) has been constructed between two transparent PDMS disks. C2C12 (mouse myoblast cell line) was used in the test. A flow velocity (0.1 mm/s &lt; vx &lt; 2.4 mm/s) of the suspension of cells was controlled by the pressure difference between the inlet and the outlet. The shifted distance of each cell along the oblique groove depends on the diameter of the cell. The malnourished cell with the different density can be distinguished by the shifted distance according to the velocity of the cell.
Experimental Analysis of Lagrangian Coherent Structures and Chaotic Mixing in Rayleigh-Benard Convection
Authors: Watanabe Masahito , Kitamura Yusuke , Hatta Naoki , Yoshimura Hiroaki 
Published: October 2020

Abstract
It is known that some fluid particles may be transported chaotically in Lagrangian description although the velocity field seems to be stable in Eulerian description. A typical example can be found in the system of two-dimensional Rayleigh-Benard convection with perturbed velocity fields, which has been investigated as a low dimensional mechanical model of fluid phenomena associated with natural convection in order to clarify the mechanism of fluid transport (see, for instance, [2]). In this study, we make an experimental study on the global structures of chaotic mixing appeared in the two-dimensional perturbed Rayleigh-Benard convection by analyzing Lagrangian coherent structures (LCSs), which correspond to the invariant manifolds of time-dependent mechanical systems. We develop an apparatus to measure the velocity field by Particle Image Velocimetry (PIV) and then show the LCSs which can be numerically detected from the experimental data by computing Finite-time Lyapunov exponent (FTLE) fields. Finally, we show the global structures of chaotic mixing appeared in the perturbed Rayleigh-Benard convection as well as the steady convection by experiments. In particular, we clarify how the LCSs are entangled with each other around the cell boundaries to carry out chaotic Lagrangian transports.
Numerical Study of Unsteady Behavior of Cloud Cavitation by Smoothed Particle Hydrodynamics
Authors: Ushioku Takahiro , Yoshimura Hiroaki 
Published: October 2020

Abstract
Cavitation generates a portion of cavities called a cavitation cloud, which performs a collective unsteady motion of repeating the process of growth and collapse. In particular, it is considered that a high-pressure shock wave propagates associated with the collapse. In order to understand such unsteady behaviors of the cavitation cloud, much effort has been made for the numerical analysis of internal flows of the cavitation cloud. However, it is not clear how such a cavitation cloud can be identified as a physical entity nor how its unsteady collective motion can be elucidated in the context of the multiphase fluid flow. In this study, we make a two-dimensional numerical analysis of the multiphase flow of the submerged bubbly water jet injecting into still water through a nozzle. To model the bubbly water jet, we employ the mixture model of liquids and gases, and we utilize the Smoothed Particle Hydrodynamics method for the numerical analysis of the unsteady flows in Lagrangian description. Finally, in order to clarify the unsteady behaviors of the cloud cavitation, we show how the cavitation cloud can be generated in the context of velocity fields in the multiphase flow and in particular, we clarify how twin vortices induced by the water jet play an essential role in the expansion and shrinkage of the cloud.
Flow Development of a Liquid Sheet Issued Into Low-Speed Airstream
Authors: Jaberi Amin , Tadjfar Mehran 
Published: October 2020

Abstract
In this study, a liquid sheet with an aspect ratio of 90 and a thickness of 0.35 was experimentally investigated when issued into a low-speed subsonic crossflow. High speed photography and shadowgraphy technique were employed to capture the instantaneous physics of the liquid sheet. Flow visualizations were used to investigate the flow development of the liquid sheet. It was found that this flow exhibited a completely different flow structure than circular or other non-circular liquid sheets. It was found that the liquid sheet developed a concave-like shape in the presence of the transverse airstream. This phenomenon, named as inflated sheet, was absent in regular circular liquid jets injected into gaseous crossflow. It was revealed the inflated sheet was the main feature of the liquid sheet that made the jet characteristics unique. The flow feature of the inflated sheet structure and its alteration with flow condition was fully examined. Moreover, the width and trajectory of the liquid sheet were quantitatively studied at different Weber numbers and for the constant momentum ratio of 40. It was found that the fluid width could be a useful parameter to distinguish different regimes of the flow.