Simulation of the double emulsion formation through a hierarchical T-junction microchannel

2015 ◽  
Vol 25 (7) ◽  
pp. 1705-1717 ◽  
Author(s):  
Milad Azarmanesh ◽  
Mousa Farhadi ◽  
Pooya Azizian
Keyword(s):  
Adaptive Mesh Refinement ◽  
Double Emulsion ◽  
Adaptive Mesh ◽  
Droplet Formation ◽  
Complex Compounds ◽  
Viscous Drag ◽  
Content Type ◽  
Encapsulation Process ◽  
One Step ◽  
The One

Purpose – The purpose of this paper is to present a practical way to create three kinds of double emulsions such as double emulsion, double-component double emulsion and viscoelastic double emulsion. Design/methodology/approach – A hierarchical T-junction microfluidic device is selected to simulate this phenomenon. A system of the three-phase flows consists of the inner, middle and outer phases were simulated by the direct numerical simulation (DNS) method. The dripping regime is considered for the droplet formation in both T-junctions. The adaptive mesh refinement technique is used to simulate the droplet formation and determine the interface rupture. Findings – The one-step and two-step encapsulation are used to create the double emulsion and the viscoelastic double emulsion, respectively. In both T-junctions, droplets are created by the balance of three parameters which are instability, viscous drag and pressure buildup. The one-step formation of double emulsion is presented for encapsulates the viscoelastic fluid. Originality/value – The simulated hierarchical microchannel shows some desirable features for creating the complex compounds. The encapsulation process is simulated in micro-scale that is useful for drug delivery applications.

A four-node membrane element model with bending modification for one-step algorithm for bus rollover impact

2015 ◽  
Vol 32 (3) ◽  
pp. 607-620 ◽  
Author(s):  
Jingxin Na ◽  
Tong Wang ◽  
Changfeng Wu ◽  
Yakun Yan
Keyword(s):  
Engineering Application ◽  
Element Model ◽  
Bending Moments ◽  
Membrane Element ◽  
Computational Accuracy ◽  
Content Type ◽  
One Step ◽  
Internal Forces ◽  
Step Algorithm ◽  
The One

Purpose – The purpose of this paper is to propose a new four-node membrane element model with bending modification based on the equilibrium principle of element nodal internal forces and bending moments for the application of the one-step algorithm for bus rollover collision. And it can be concluded whether the proposed four-node membrane element model has practical value in engineering application or not. Design/methodology/approach – Based on the equilibrium principle of element nodal internal forces and bending moments, the paper puts forward a four-node membrane element model with bending modification. A case study on the rollover of a typical bus body section is carried out by using the one-step algorithm for bus rollover collision to verify the effectiveness of the proposed element model. Findings – For the simulation of bus rollover collision, the computational accuracy can be guaranteed, meanwhile, the calculated amount is much smaller than the shell element, and computational efficiency is improved significantly. Originality/value – The proposed four-node membrane element model is used for the simulation of bus rollover collision for the first time. It holds the advantage of high computational efficiency of membrane element, and the computational accuracy is improved as well. In conclusion, it has some practical value in engineering application.

Simulations of flame propagation during the ignition process in an annular multiple-injector combustor

2019 ◽  
Vol 29 (6) ◽  
pp. 1947-1964 ◽  
Author(s):  
Dongmei Zhao ◽  
Yifan Xia ◽  
Haiwen Ge ◽  
Qizhao Lin ◽  
Jianfeng Zou ◽  
...  
Keyword(s):  
Flame Propagation ◽  
Adaptive Mesh Refinement ◽  
High Speed ◽  
Early Stage ◽  
Adaptive Mesh ◽  
Critical Issue ◽  
Experimental Investigations ◽  
Ignition Process ◽  
High Speed Imaging ◽  
Content Type

Purpose Ignition process is a critical issue in combustion systems. It is particularly important for reliability and safety prospects of aero-engine. This paper aims to numerically investigate the burner-to-burner propagation during ignition process in a full annular multiple-injector combustor and then validate it by comparing with experimental results. Design/methodology/approach The annular multiple-injector experimental setup features 16 swirling injectors and two quartz tubes providing optical accesses to high-speed imaging of flames. A Reynolds averaged Navier–Stokes model, adaptive mesh refinement (AMR) and complete San Diego chemistry are used to predict the ignition process. Findings The ignition process shows an overall agreement with experiment. The integrated heat release rate of simulation and the integrated light intensity of experiment is also within reasonable agreement. The flow structure and flame propagation dynamics are carefully analyzed. It is found that the flame fronts propagate symmetrically at an early stage and asymmetrically near merging stage. The flame speed slows down before flame merging. Overall, the numerical results show that the present numerical model can reliably predict the flame propagation during the ignition process. Originality/value The dedicated AMR method together with detailed chemistry is used for predicting the unsteady ignition procedure in a laboratory-scale annular combustor for the first time. The validation shows satisfying agreements with the experimental investigations. Some details of flow structures are revealed to explain the characteristics of unsteady flame propagations.

Impacts of mobile termination rates on retail prices: the implication for regulators

Info ◽  
2014 ◽  
Vol 16 (2) ◽  
pp. 80-93 ◽  
Author(s):  
Chatchai Kongaut ◽  
Erik Bohlin
Keyword(s):  
Method Of Moments ◽  
Consumer Welfare ◽  
Dynamic Panel Data ◽  
Dynamic Panel ◽  
Content Type ◽  
Retail Prices ◽  
One Step ◽  
Generalised Method Of Moments ◽  
The One ◽  
The Empirical Analysis

Purpose – There are only a limited number of empirical analyses on the impacts of MTRs. According to the data from 2006-2011 by the European Regulators Group (ERG), many countries have continuously reduced their MTRs. This paper therefore aims to enrich the empirical analysis of the impacts of MTRs according to EC policy on retail prices. Design/methodology/approach – This paper applies the one-step generalised method of moments (GMM) approach to dynamic panel data. Findings – The results support the hypothesis that lower MTRs will reduce consumer retail prices, which is consistent with the EC framework. It is therefore recommended that regulators in the calling party network pays (CPNP) regime reduce MTRs to at least the same level as the operators' cost to raise overall social welfare, especially consumer welfare. However, the approach by each country can differ depending on its situation. Originality/value – This study supports the idea that it is appropriate for the EC to regulate MTRs by reducing the rates to at least the same level as the efficient operators' cost, and other regulators with a calling party network pays regime from other regions could also follow this strategy.

The implementation of extrapolation with smoothing technique in solving stiff ordinary differential equations

2020 ◽  
Vol 11 (4) ◽  
pp. 567-578
Author(s):  
Noorhelyna Razali ◽  
Alias Jedi ◽  
Nuryazmin Ahmat Zainuri
Keyword(s):  
Differential Equations ◽  
Ordinary Differential Equations ◽  
Computation Time ◽  
Order Reduction ◽  
Smoothing Technique ◽  
Content Type ◽  
Stiff Ordinary Differential Equations ◽  
One Step ◽  
The One ◽  
Symmetric Method

PurposeExtrapolation is a process used to accelerate the convergence of a sequence of approximations to the true value. Different stepsizes are used to obtain approximate solutions, which are combined to increase the order of the approximation by eliminating leading error terms. The smoothing technique is also applied to suppress order reduction and to dampen the oscillatory component in the numerical solution when solving stiff problems. The extrapolation and smoothing technique can be applied in either active, passive or the combination of both active and passive modes. In this paper, the authors investigate the best strategy of implementing extrapolation and smoothing technique and use this strategy to solve stiff ordinary differential equations. Based on the experiment, the authors suggest using passive smoothing in order to reduce the computation time.Design/methodology/approachThe two-step smoothing is a composition of four steps of the symmetric method with different weights. It is used as the final two steps when combined with many steps of the symmetric method. The aim is to preserve symmetry and provide damping for stiff problem and to be more robust than the one-step smoothing. The two-step smoothing is L-stable. The new method is then applied with extrapolation process in passive and active modes to investigate the most efficient and accurate method of implementation.FindingsIn this paper, the authors constructed the two-step smoothing to be more robust than the one-step smoothing. The two-step smoothing is constructed to achieve as high order as possible and able to restore the classical order of particular method compared to the one-step active smoothing that is only able to achieve order-1 condition. The two-step smoothing for ITR is also superior in solving stiff case since it has the super-convergent order-4 behavior. In our experiments with extrapolation, it is proven that the two-step smoothing is more accurate and more efficient than the one-step smoothing, namely 1ASAX. It is also observed that the method with smoothing is comparable if not superior to the existing base method in certain cases. Based on the experiment, the authors would suggest using passive smoothing if the aim is to reduce computation time. It is of interest to conduct more experiment to validate the accuracy and efficiency of the smoothing formula with and without extrapolation.Originality/valueThe implementation of extrapolation on two-step symmetric Runge–Kutta method has not been tested on variety of other test problems yet. The two-step symmetrization is an extension of the one-step symmetrization and has not been constructed by other researchers yet. The method is constructed such that it preserves the asymptotic error expansion in even powers of stepsize, and when used with extrapolation the order might increase by 2 at a time. The method is also L-stable and eliminates the order reduction phenomenon when solving stiff ODEs. It is also of interest to observe other ways of implementing extrapolation using other sequences or with interpolation.

scholarly journals Numerical simulation of detonation structures using a thermodynamically consistent and fully conservative reactive flow model for multi-component computations

2009 ◽  
Vol 465 (2107) ◽  
pp. 2135-2153 ◽  
Author(s):  
Giuki Cael ◽  
Hoi Dick Ng ◽  
Kevin R. Bates ◽  
Nikos Nikiforakis ◽  
Mark Short
Keyword(s):  
Numerical Simulation ◽  
High Resolution ◽  
Adaptive Mesh Refinement ◽  
Adaptive Mesh ◽  
Combustible Mixture ◽  
Reactive Flow ◽  
Detonation Waves ◽  
Detailed Chemistry ◽  
Cellular Detonation ◽  
The One

This paper presents a simplified reactive multi-gas model for the numerical simulation of detonation waves. The mathematical model is formulated based on a thermodynamically consistent and fully conservative formulation, and is extended to model reactive flow by considering the reactant and product gases as two constituents of the system and modelling the conversion between these by a simple one-step reaction mechanism. This simplified model allows simulations using more appropriate chemico-thermodynamic properties of the combustible mixture and yields close Chapman–Jouguet detonation parameters from detailed chemistry. The governing equations are approximated using a high-resolution finite volume centred scheme in an adaptive mesh refinement code, permitting high-resolution simulations to be performed at flow regions of interest. The algorithm is tested and validated by comparing results to predictions of the one-dimensional linear stability analysis of the steady detonation and through the study of the evolution of two-dimensional cellular detonation waves in gaseous hydrogen-based mixtures.

An exploration of the impact of artificial intelligence (AI) and automation for communication professionals

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Eduardo Alejandro López Jiménez ◽  
Tania Ouariachi
Keyword(s):  
Artificial Intelligence ◽  
Human Life ◽  
Content Type ◽  
Methodological Triangulation ◽  
Analytical Thinking ◽  
One Step ◽  
Automated Tools ◽  
The One ◽  
The Impact ◽  
Near Future

Purpose Artificial intelligence (AI) and automation are currently changing human life with a great implication in the communication field. This research focusses on understanding the current and growing impact of AI and automation in the role of communication professionals to identify what skills and training are needed to face its impacts leading to a recommendation. Design/methodology/approach The research involves methodological triangulation, analysing and comparing data gathered from consulting with experts using the Delphi method, focus group with communication students, and literature review. Findings Findings show that the likely impacts are on the one hand the enhancing of efficiency and productivity, as well as freeing communication professionals to focus on the creative side, strategy and analytical thinking, on the other hand, repetitive and low-level jobs could be lost, being higher position jobs or those involving creativity and decision making harder to automate. Two types of training are needed: to gather experience with the current AI and automated tools, and to focus on developing human qualities that AI cannot replicate. Originality/value The outcomes of this research are valuable to help current and future communication practitioners, as well as organisations, to be one step ahead and survive the age AI and automation, being aware of its current and near-future impacts. The paper offers a list of recommended soft and technical skills, as well as training needed, categorizing them in low, medium and high priority.

scholarly journals New boundary conditions for simulating the filling stage of the injection molding process

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wagner de Campos Galuppo ◽  
Ana Magalhães ◽  
Luís Lima Ferrás ◽  
João Miguel Nóbrega ◽  
Célio Fernandes
Keyword(s):  
Injection Molding ◽  
Boundary Conditions ◽  
Adaptive Mesh Refinement ◽  
Complex Geometry ◽  
Real Life ◽  
Adaptive Mesh ◽  
Injection Molding Process ◽  
Molding Process ◽  
Content Type ◽  
Filling Stage

Purpose The purpose of this paper is to develop new boundary conditions for simulating the injection molding process of polymer melts. Design/methodology/approach The boundary conditions are derived and implemented to simulate real-life air vents (used to allow the air escape from the mold). The simulations are performed in the computational library OpenFOAM® by considering two different fluid models, namely, Newtonian and generalized Newtonian (Bird–Carreau model). Findings A detailed study on the accuracy of the solver interFoam for simulating the filling stage is presented, by considering simple geometries and adaptive mesh refinement. The verified code is then used to study the three-dimensional filling of a more complex geometry. Originality/value The results obtained showed that the numerical method is stable and allows one to model the filling process, simulating the real injection molding process.

Adaptive discrete-continuous modeling of evolving discontinuities

2014 ◽  
Vol 31 (7) ◽  
pp. 1305-1320 ◽  
Author(s):  
Annika Sorg ◽  
Manfred Bischoff
Keyword(s):  
Adaptive Mesh Refinement ◽  
Large Scale ◽  
Adaptive Mesh ◽  
Accurate Solution ◽  
Constitutive Law ◽  
Smooth Transition ◽  
Content Type ◽  
Quasicontinuum Method ◽  
Starting Point ◽  
Frictional Materials

Purpose – The purpose of this paper is to develop a method to model entire structures on a large scale, at the same time taking into account localized non-linear phenomena of the discrete microstructure of cohesive-frictional materials. Design/methodology/approach – Finite element (FEM) based continuum methods are generally considered appropriate as long as solutions are smooth. However, when discontinuities like cracks and fragmentation appear and evolve, application of models that take into account (evolving) microstructures may be advantageous. One popular model to simulate behavior of cohesive-frictional materials is the discrete element method (DEM). However, even if the microscale is close to the macroscale, DEMs are computationally expensive and can only be applied to relatively small specimen sizes and time intervals. Hence, a method is desirable that combines efficiency of FEM with accuracy of DEM by adaptively switching from the continuous to the discrete model where necessary. Findings – An existing method which allows smooth transition between discrete and continuous models is the quasicontinuum method, developed in the field of atomistic simulations. It is taken as a starting point and its concepts are extended to applications in structural mechanics in this paper. The kinematics in the method presented herein is obtained from FEM whereas DEM yields the constitutive behavior. With respect to the constitutive law, three levels of resolution – continuous, intermediate and discrete – are introduced. Originality/value – The overall concept combines model adaptation with adaptive mesh refinement with the aim to obtain a most efficient and accurate solution.

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