Problem Of Breakup Research Articles

NMP limits silver particle size to solve deposited film breakup problems

Metal based electroreflective devices (MERDs) have gained wide attention in recent years in the fields of smart windows and automotive glass due to their excellent photo-thermal modulation capability in the visible and near-infrared wavelength bands due to their high reflectivity. However, the high porosity due to the island-like growth of silver particles makes the devices susceptible to electrodeposited film breakage during prolonged energization or bleaching. This will seriously affect the effectiveness and stability of the device. In this paper, it is shown that the problem of Ag electrodeposition film fragmentation can be effectively overcome by replacing dimethyl sulfoxide solvent by N-methylpyrrolidone (NMP). The optical constants during film deposition were tested by the spectroscopic ellipsometry technique, and the porosity was calculated (reduced by 21.6%). The results show that MERDs with NMP as the solvent have more and more dispersed silver deposition sites, which leads to lower porosity of the silver deposited film during the deposition process. In addition, the lower turn-on voltage, greater contrast, longer memory effect, and greater coloring efficiency reveal that they are more promising for energy-saving applications.

Marriage by Proxy: A Remedy to Divorce and Single Parenting as Presented in Ifá Ogbèdí Divination Poetry

Marriage is an important aspect of life in Africa and other nations around the world. In Africa, particularly among the Yorùbá, marriage institution is sacredly ordained by Olódùmarè for the purpose of procreation and mutual help. Therefore, anyone in the society that has attained marriageable age is expected to marry notwithstanding any form of deformity. However, it is unfortunate that the institution of marriage in the world today is facing a lot of hitches leading to divorce, and eventually, single parenting. In the past, marriage by proxy, which means marriage that follows due process with the help of intermediary and Ifá divination, was, considerably helpful in sustaining marital union. However today, some people have attributed the problem of marriage breakup to abandoned culture and modernity through Western education, foreign culture, and religions, while others premise it on women’s liberation. Yet, the latter argument may not be strong enough since many prominent women were successful in their business enterprises and marriage even in times of the gods such as Ajé who had 200 slaves that helped her to take her wares to the market. Whether these shared views are true or there are other factors associated with the issue of marriage and divorce is what this paper tries to find out. Hence, ten men and women were interviewed from each three principal religions in Nigeria and their opinions were content analyzed. Regardless of religious affiliation, at least 82% of the respondents agreed that foreign culture, religion, and education extremely contributed to the decline of African culture, which gave room for divorce of which the end product is single parenting.

Stranding continental crustal fragments during continent breakup: Mantle suture reactivation in the Nain Province of Eastern Canada

AbstractEarth’s continental crust has evolved through a series of supercontinent cycles, resulting in a patchwork of Archean cores surrounded by terranes, fragments, and slivers of younger crustal additions. However, the dispersal (and/or stranding) of continental fragments during breakup is not well understood. Inherited structures from previous tectonic activity may explain the generation of continental terranes by controlling first-order deformation during rifting. Here, we explored the influence of lithospheric deformation related to ancient orogenesis, focusing on the impact of the Torngat orogen in the genesis of the Nain Province continental fragment in Eastern Canada. We present three-dimensional continental extension models in the presence of an inherited lithospheric structure and show that a narrow continental terrane could be separated and stranded by deep lithospheric scarring. The results show that continental terranes formed by this method would be limited to a width of 100–150 km, imposed by tectonic conditions during continental suturing. The findings have broad implications, demonstrating an original theory on the fundamental geologic problem of terrane generation and continent breakup.

FRAGMENTATION OF WATER DROPS IN COLLISION WITH A SMALL OBSTACLE

The study is dedicated to the general features of the processes of deformation and fragmentation of liquid drops have been studied when they collide with obstacles. Masks and filters, protecting against airborne infections, are among the possible obstacles. Coughing, sneezing, and talking cause the ejection of drops of saliva and bronchial mucus. A local drop-mask or drop-filter collision is modeled by the impact of a drop on a small obstacle as the simplest hydrodynamic case with a minimum number of influencing factors. For water-based oral and bronchial drops with a typical diameter <i>d<sub>i</sub></i> = 100 μm and impact velocity of the order of <i>v<sub>i</sub></i> = 10 m/s, the impact Weber number is about We<sub><i>i</i></sub> = ρ<i>v<sub>i</sub></i><sup>2</sup><i>d<sub>i</sub></i>/γ = 139. As a starting point in the problem of the drop breakup in a collision with a solid obstacle, we consider the coaxial impact of an inviscid liquid drop with a diameter of 2.8 mm on a disk with a diameter of 4.0 mm. In laboratory experiments, the similarity was provided by impact velocities of 1.88-3.57 m/s, which gives impact Weber numbers We<sub><i>i</i></sub> = 137-496. Such collisions are controlled only by inertia and capillarity, while the influence of all other factors is negligible. A round liquid lamella with a torus-shaped rim is formed upon the collision. The rim first expands and then retracts, forming radially directed liquid fingers in the rim. At low impact velocities, the fingers retained continuity, while at sufficiently high velocities, the fingers spattered into secondary droplets. Experiments have shown that the critical Weber number corresponding to the transition to spattering lies between 137 and 206. Approximately the same values of the Weber number occur when infected drops hit masks or filters.

Fractional-order integral generalization of the Rapoport–Leas equation

A one-dimensional time-fractional integral model for a two-phase flow through a porous medium with power-law memory in the presence of capillary forces is considered. Based on the time-fractional integral generalization of Darcy’s law and the classical mass balance equations for phases, neglecting gravity forces, a time-fractional integral generalization of the Rapoport–Leas equation is derived. It is shown that in the limiting case of constant capillary pressure, the obtained equation coincides with the classical Buckley–Leverett equation. An example of initial boundary value problem for the derived fractional integral equation is given for the case of a finite reservoir. Unlike the classical Rapoport–Leas equation, its time-fractional integral analogue does not have a traveling wave solution in general case. It is due to the fact that the fractional integral with a finite lower limit is not invariant with respect to translations in time. However, for the model problem of two-phase displacement in an unbounded reservoir, considered as a discontinuity breakup problem, the full memory approximation is valid. In this case the obtained equation has a traveling wave solution. In this approximation, relations for the main characteristics of the saturation jump on the shock are obtained. In particular, it is shown that the speed of the shock can be found from an equation that includes the time-fractional integral characteristic of the Leverett function. The behavior of the shock near its left and right boundaries is also asymptotically studied for different saturation levels at the boundaries. It has been proven that if the initial saturation exceeds the residual saturation of the displacing phase, then on the right boundary the saturation at the jump exponentially tends to the initial one. On the left boundary, the asymptotic behavior of the jump is also exponential, with the exception of one special case in which it becomes a fractional power law. For the equation in question, an approximate solution has been analytically constructed for the case of «weak» full memory, when the order of fractional integration is close to zero and can be considered as a small parameter.

Formation of high-viscosity micro-droplets in T-channels with neck structure induced by surface acoustic waves

In the fields of organ printing and drug preparation, high-precision and stable dispersion of high-viscosity biomaterials enable precise control of organ morphology and drug release rate. This paper proposes the use of an acoustic surface wave to overcome the problem of unstable interface breakup and weak size controllability when the traditional passive droplet microfluidics is applied to high-viscosity (higher than 0.4 Pa·s) dispersed phases. This paper studies the internal flow behavior of high-viscosity fluid under the influence of an acoustic field and realizes the accurate prediction of formation regime and droplet size. Experimental results show that with the increase in acoustic power, three unique droplet generation regimes (e.g., long jetting, transition, and dripping) exist. The transition regime is most suitable for high-throughput preparation of high-viscosity droplets, and its corresponding flow and acoustic conditions can be predicted by equation μd/μc = 4.8 × 10−8 (μc × vc/AP02 × w)−3.32. Affected by the regime transition, the droplet size increases with the increase in acoustic power. The droplet size prediction can be realized based on the capillary number Caf, which represents the intensity of the acoustic field.

Evaluation and Improvements to Interfacial Curvature Predictions in interFoam

Improvements to the interfacial curvature of interFoam based on (i) the smoothing of the liquid fraction field and (ii) the creation of a signed distance function (ϕ-based) are implemented. While previous work in this area has focused on evaluating spurious currents and similar configurations, the tests implemented in this work are more applicable to sprays and hydrodynamic breakup problems. For the ϕ-based method, a dual approach is developed based on a geometric reconstruction of the interface at interfacial cells and the solution of the Hamilton-Jacobi equation away from these cells. The more promising results are from this method, where the lack of convergence of Laplace pressure predictions existing in the standard version of interFoam is fixed, resulting in second-order convergence. Similar but less drastic improvements are observed for other exercises consisting of the oscillation of a droplet, a 2-phase Orr–Sommerfeld problem, the Rayleigh–Plateau instability, and the retraction of a liquid column. It is only when the dynamics are either entirely governed by surface tension or are heavily influenced by it that we see the need to substitute the standard interFoam curvature approach with a more accurate scheme. For more realistic problems, which naturally include more complicated dynamics, the difference between the standard approach and the ϕ-based approach is minimal.

Narcissistic admiration and rivalry and reactions to romantic breakup

This study examined how narcissism, described by the Narcissistic Admiration and Rivalry Concept (NARC), relates to reactions to romantic relationship dissolution. 246 participants completed a survey assessing the NARC components, and measures concerning a specific past relationship: Emotional reactions immediately following breakup, perceptions of the ex-partner, responsibility for initiating and attributions of blame for problems leading to breakup. Narcissistic rivalry was associated with greater externalized (anger) and internalized (sadness and anxiety) negative emotion, while narcissistic admiration was associated with greater anger and less sadness. Narcissistic admiration was associated with more positive and rivalry with more negative trait perceptions of the ex-partner. Narcissism was unrelated to attributions of blame for the breakup or relationship problems, but admiration was associated with a greater role in initiating breakup.

ANALYTICAL STUDY OF THE MECHANISM OF DROPLET DEFORMATION AND BREAKUP IN SHEAR FLOWS

The problem of drop deformation and breakup in shear flow represents academic and practical interest and has attracted close attention over the intervening decades. Drop breakup is important for a wide range of engineering and biomedical applications including production and processing of emulsions, aerosols, etc. Although drop breakup operations are widely used in various industries, however, till quite presently there is no unequivocal treatment of the physical mechanism, which causes the fragmentation of dispersions in shear flows. In this paper the principles of constructing a mathematical model, which predicts the evolution of initially spherical droplet in shear flows of viscous liquid over a wide range of flow regimes as well physical parameters of both liquid phases, are considered. A mathematical model is presented that describes the deformation of a single drop suspended in another immiscible liquid under the combined action of three forces, namely, hydrodynamic force, capillary force and dissipative viscous force. The influence of each of these forces on the process of droplet deformation is discussed in the paper.
 The focus of the study is to more deeply analyze the dynamics of droplet deformation in shear flows and the transitional effects associated with current droplet shapes. Particular attention is paid to the analysis of critical conditions for the onset of irreversible deformation of droplets, which leads to their destruction. The deformed droplet is assumed to be in the form of prolate ellipsoid of revolution. The drop deformation is regarded as motion of the centers mass of the half-drops, symmetrical with respect to the drop center.
 The results of numerical calculations for droplet deformation in shear flows in comparison with experimental data of other authors are presented. A simple criterion for destruction of droplets in shear flows has been obtained. The results of the analysis confirm the reliability of the model and the competency of the assumption made. The model is able to predict the nature of droplet deformation and the conditions for their destruction in shear flows with known operating parameters with a greater degree of accuracy than the existing empirical relationships.

Pre-compensation method for optimizing recording process of holographic optical element lenses with spherical wave reconstruction.

We propose a pre-compensated recording process of holographic optical element (HOE) lenses, where both of reference and signal waves have spherical wavefronts, for solving a wavelength mismatch problem between the recording and displaying process. Based on a localized approximation for aperiodic volume gratings, the wavelength mismatch and shrinkage effects are pre-compensated by optimizing the recording setup of HOE lenses, so that the Bragg condition of each local grating is satisfied. In order to realize the practical implementations of recording setup, complicated wavefronts to be required for the wavelength and shrinkage compensation are approximated into spherical waves. The simulation results using the volume hologram models of OpticStudio verify that the undesirable focal shift and color breakup problems in the HOE lens due to the wavelength mismatch are compensated. Displaying experiments using a full-color HOE lens with the field of view of 30° are presented, where the maximum wavelength mismatch between the recording and displaying process is 17 nm.

Breakup criterion for droplets exposed to the unsteady flow generated by an incoming aerodynamic surface

An experimental and theoretical study is presented on the problem of droplet breakup exposed to a continuously accelerating flow generated by an incoming aerodynamics surface. Droplet breakup experiments were carried out in a rotating arm facility. Droplet diameters were of the order of 1 mm. The maximum velocity of the airfoils located at the end of the rotating arm was 90 m/s. Droplet deformation was computed using a phenomenological model developed previously by the authors. The dynamics of this deformation was coupled to an instability model based on the growth of Rayleigh-Taylor waves at the droplet surface. It was found that, within the experimental uncertainty, breakup occurs when the instability wavelength approaches the droplet hydraulic diameter assuming that it flattens and deforms as an oblate spheroid. This fact allowed for the generation of a theoretical closed-form droplet deformation and breakup model that predicts the onset of breakup with discrepancies of about ±10% when compared to the experimental results. Finally, as an application case, this closed-form model is used to simulate an actual situation in which the objective is to investigate whether a series of droplets that are approached by an airfoil either impact on its surface, or break prior to collision, or break without colliding, or pass through undamaged.

A multi-phase SPH model based on Riemann solvers for simulation of jet breakup

The discontinuous physical properties of the multiphase flow interface lead to the numerical instability, especially for the multiphase flow problems with large density or viscosity ratios. Based on Riemann solution, a novel multiphase SPH model is presented. The momentum equation of the Riemann form is improved to calculate the physical viscosity of multiphase flow and decrease the Riemann dissipation. The solid-wall boundary is imposed by one-sided Riemann problem. In addition, a repulsive force and the surface tension are applied on both sides of the multiphase interface to keep the interface sharpness and consider the small-scale interface effect. Three cases, squared droplet oscillating, single bubble rising (with different density and viscosity ratios) and two-bubble rising examples, are simulated to demonstrate the accuracy and effectiveness of the proposed method in dealing with the multiphase flow problems with the wide range of density and viscosity ratios and with the complex interfaces. Finally, the jet breakup problems of steady jets and pulsating jets are studied using the present model. A detailed process of jet breakup is observed, the surface wave structure of liquid jet could be identified. The influence of jet parameters (surface tension, velocity amplitude and velocity period) on physical information of jet is analyzed.

Hydrodynamic behavior of the pseudopotential lattice Boltzmann method for interfacial flows.

The lattice Boltzmann method (LBM) is routinely employed in the simulation of complex multiphase flows comprising bulk phases separated by nonideal interfaces. The LBM is intrinsically mesoscale with a hydrodynamic equivalence popularly set by the Chapman-Enskog analysis, requiring that fields slowly vary in space and time. The latter assumptions become questionable close to interfaces where the method is also known to be affected by spurious nonhydrodynamical contributions. This calls for quantitative hydrodynamical checks. In this paper, we analyze the hydrodynamic behavior of the LBM pseudopotential models for the problem of the breakup of a liquid ligament triggered by the Plateau-Rayleigh instability. Simulations are performed at fixed interface thickness, while increasing the ligament radius, i.e., in the "sharp interface" limit. The influence of different LBM collision operators is also assessed. We find that different distributions of spurious currents along the interface may change the outcome of the pseudopotential model simulations quite sensibly, which suggests that a proper fine-tuning of pseudopotential models in time-dependent problems is needed before the utilization in concrete applications. Taken all together, we argue that the results of the proposed paper provide a valuable insight for engineering pseudopotential model applications involving the hydrodynamics of liquid jets.

Single seed precise sowing of maize using computer simulation.

In order to test the feasibility of computer simulation in field maize planting, the selection of the method of single seed precise sowing in maize is studied based on the quadratic function model Y = A×(D-Dm)2+Ym, which depicts the relationship between maize yield and planting density. And the advantages and disadvantages of the two planting methods under the condition of single seed sowing are also compared: Method 1 is optimum density planting, while Method 2 is the ideal seedling emergence number planting. It is found that the yield reduction rate and yield fluctuation of Method 2 are all lower than those of Method 1. The yield of Method 2 increased by at least 0.043 t/hm2, and showed more advantages over Method 1 with higher yield level. Further study made on the influence of seedling emergence rate on the yield of maize finds that the yields of the two methods are both highly positively correlated with the seedling emergence rate and the standard deviations of their yields are both highly negatively correlated with the seedling emergence rate. For the study of the break-up problem of sparse caused by the method of single seed precise sowing, the definition of seedling missing spots is put forward. The study found that the relationship between number of hundred-dot spot and field seedling emergence rate is as the parabola function y = -189.32x2 + 309.55x - 118.95 and the relationship between number of spot missing seedling and field seedling emergence rate is as the negative exponent function y = 395.69e-6.144x. The results may help to guide the maize seeds production and single seed precise sowing to some extent.

Ink-jet printed transparent and flexible electrodes based on silver nanoparticles

In recent, silver (Ag) nanowires (NWs) have received much attention as an alternative to indium tin oxide (ITO) for transparent electrode application in printed and transparent electronics. However, Ag NWs have its breakup problem by joule heating during current. To overcome this problem, this paper demonstrates a mesh type electrode based on Ag nanoparticles, which is fabricated on PET substrate through an ink-jet printing technique. The proposed electrode has a low resistance of 108.5 Ω/sq and a good optical transparency around 92% at 300–800 nm. It has a relationship that the sheet resistance drops with the decrease of transparency due to depending hole size and the best curing temperature is found to be 120 °C. It also demonstrate an excellent flexible stability, showing < 2% resistance change after over 100 bending cycles. These resistance and transparency are similar with that of commercially ITO electrode, and are superior to other alternatives such as carbon nanotube electrodes. The proposed electrode can be considered as a commercial electrode to as an alternative to ITO electrode.

Numerical investigation of turbulent-jet primary breakup using one-dimensional turbulence

Primary breakup to form droplets at liquid surfaces is an important fundamental process to study as it determines the initial properties of the dispersed phase, which affect mixing rates, secondary breakup, droplet collisions, and flow separation within the dispersed flow region. Primary breakup can be regarded as one of the least developed model components for simulating and predicting liquid jet breakup. However, it is of paramount importance in many technical applications, e.g. fuel injection in engines and spray painting. This paper presents a numerical investigation of primary breakup of a turbulent liquid jet in still air at standard conditions using the one-dimensional turbulence (ODT) modeling framework. ODT is a stochastic model that simulates turbulent flow evolution along a notional 1D line of sight by applying instantaneous maps to represent the effect of individual turbulent eddies on property profiles. An important feature of ODT is the resolution of all relevant scales, both temporal and spatial. The restriction to one spatial dimension in ODT permits affordable high resolution of interfacial and single-phase property gradients, which is key to capturing the local behavior of the breakup process and allows simulations at high Reynolds and Weber numbers that are currently not accessible to direct numerical simulations (DNS).This paper summarizes our extensions of the ODT model to simulate geometrically simple jet breakup problems, including representations of Rayleigh wave breakup, turbulent breakup, and shear-driven breakup. Each jet breakup simulation consists of a short temporal channel section to initialize a turbulent velocity profile at the nozzle exit followed by an adjacent jet section. The simulations are carried out for jet exit Reynolds number of 11,500, 23,000, 46,000 and 92,000 while the Weber number is varied within the range 102–107. We present results on breakup statistics including spatial locations of droplet release, droplet sizes and liquid core length. The results on primary breakup are compared to experimental results and models.

Justification of Godunov’s scheme in the multidimensional case

The classical Godunov scheme for the numerical solution of 3D gas dynamics equations is justified in the multidimensional case. An estimate is obtained for the error induced by replacing the exact solution of the multidimensional discontinuity breakup problem (known as the Riemann problem) with the solution of the 1D problems with the data on the left and right of the interface of each cell without considering the complicated flow in the neighborhood of the cells’ vertices. It is shown that, in the case of plane interfaces, the error has the first order of smallness in the time step and the approximate solution converges to the solution of semidiscrete equations as the time step vanishes. In fact, the time integration of these equations using the explicit Euler method represents the Godunov scheme.

A model of cavitation for the treatment of a moving liquid metal volume

A homogeneous cavitation model, derived from the Keller–Miksis equation, is developed and applied to the two-phase problem of bubble growth, break-up and propagation in the melt. Numerical simulations of the ultrasonic field emanating from an immersed sonotrode are performed, and the calculated acoustic pressure is applied to the source term of the bubble transport equation to predict the generation, propagation and collapse of cavitation bubbles in the melt. The use of baffles to modify the flow pattern and amplify sound waves in a launder conduit is examined to determine the optimum configuration that maximizes the residence time of the liquid in high cavitation activity regions. The simulation results demonstrate that dimensions that match integer wavelengths, and are therefore in resonance with the travelling waves, are desirable since they lead to an increase in the concentration of nucleating bubbles in the liquid compared with other dimensions.

Recent Advances in Nuclear Reaction Theories for Weakly Bound Nuclei: Reexamining the Problem of Inclusive Breakup

The problem of the calculation of inclusive breakup cross sections in nuclear reactions is reexamined. For that purpose, the theory proposed by Ichimura et al. (Phys Rev C 32:431, 1985) is revisited, both in its prior and post representations. We briefly outline the connection of this theory with that proposed by Udagawa and Tamura (Phys Rev C 24:1348, 1981) and apply both theories to the inclusive breakup of \(^6\)Li on \(^{209}\)Bi at near-barrier energies, comparing also with available data. The relative importance of elastic versus non-elastic breakup, as a function of the incident energy and of the projectile separation energy, is also investigated.

A fast and robust computational method for the ionization cross sections of the driven Schrödinger equation using an O(N) multigrid-based scheme

This paper improves the convergence and robustness of a multigrid-based solver for the cross sections of the driven Schrodinger equation. Adding a Coupled Channel Correction Step (CCCS) after each multigrid (MG) V-cycle efficiently removes the errors that remain after the V-cycle sweep. The combined iterative solution scheme (MG-CCCS) is shown to feature significantly improved convergence rates over the classical MG method at energies where bound states dominate the solution, resulting in a fast and scalable solution method for the complex-valued Schrodinger break-up problem for any energy regime. The proposed solver displays optimal scaling; a solution is found in a time that is linear in the number of unknowns. The method is validated on a 2D Temkin-Poet model problem, and convergence results both as a solver and preconditioner are provided to support the O ( N ) scalability of the method. This paper extends the applicability of the complex contour approach for far field map computation (Cools et al. (2014) 10).