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In this paper we present the comparison of experiments and numerical simulations for bubble cutting by a wire. The air bubble is surrounded by water. In the experimental setup an air bubble is injected on the bottom of a water column. When the bubble rises and contacts the wire, it is separated into two daughter bubbles. The flow is modeled by the incompressible Navier-Stokes equations. A meshfree method is used to simulate the bubble cutting. We have observed that the experimental and numerical results are in very good agreement. Moreover, we have further presented simulation results for liquid with higher viscosity. In this case the numerical results are close to previously published results., Comment: 20 pages, 12 figures. arXiv admin note: text overlap with arXiv:1406.4734

We study a two phase flow with interactions of liquid and rarefied gas inside the gas phase. The gas phase is modeled by the BGK model of the Boltzmann equation. The liquid phase is modeled by the incompressible Navier-Stokes equations. In this paper we have excluded the heat transfer between two phases. The interface boundary conditions for the liquid and gas phases is presented. The BGK model is solved by a semi-Lagrangian scheme with a meshfree reconstruction since the droplet moves inside the gas phase and its interface deforms with respect to time and space. Therefore, the similar meshfree particle method is also suitable to solve the incompressible Navier-Stokes equations for liquid phase. To validate the coupled solutions of the BGK model and the incompressible Navier-Stokes equations, we have compared the results of the BGK model and the incompressible Navier-Stokes equations, with those of the Boltzmann and the incompressible Navier-Stokes equations, where the Boltzmann equation is solved by a DSMC method. Results in $1D$ and $2D$ physical spaces are presented.

Meshfree solution schemes for the incompressible Navier–Stokes equations are usually based on algorithms commonly used in finite volume methods, such as projection methods, SIMPLE and PISO algorithms. However, drawbacks of these algorithms that are specific to meshfree methods have often been overlooked. In this paper, we study the drawbacks of conventionally used meshfree Generalized Finite Difference Method (GFDM) schemes for Lagrangian incompressible Navier–Stokes equations, both operator splitting schemes and monolithic schemes. The major drawback of most of these schemes is inaccurate local approximations to the mass conservation condition. Further, we propose a new modification of a commonly used monolithic scheme that overcomes these problems and shows a better approximation for the velocity divergence condition. We then perform a numerical comparison which shows the new monolithic scheme to be more accurate than existing schemes.

Material flow simulation is in increasing need of multi-scale models. On the one hand, macroscopic flow models are used for large-scale simulations with a large number of parts. On the other hand, microscopic models are needed to describe the details of the production process. In this paper, we present a hierarchy of models for material flow problems ranging from detailed microscopic, discrete element method type, models to macroscopic models using scalar conservation laws with non-local interaction terms. Numerical simulations are presented at all levels of the hierarchy, and the results are compared to each other for several test cases.

Simulations of wetting phenomena by a meshfree particle method are presented. The incompressible Navier-Stokes equations are used to model the two-phase flow. The continuous surface force model is used to incorporate the surface tension force. Chorin's projection method is applied to discretize the Navier-Stokes equations. The different fluid phases are identified by assigning different colors and different material properties (density, viscosity) to the particles that remain unchanged throughout a simulation. Two-phase flow is captured by a one-fluid model via using weighted averages of the density and viscosity in a region around the fluid-fluid interface. The differential operators at each particle are computed from the surrounding cloud of particles with the help of the least-squares method. The numerical results are compared with specific analytical solutions, but also with previously considered test cases involving wetting of a container and sessile drops. A good overall agreement is found., 34 pages, 41 figures

A dual-band microstrip patch antenna is designed and analyzed using metamaterial artificial substrate. Metamaterial based substrate is designed using Square Split Ring Resonator (SSRR) and Wire Strip. The antenna is tuned to work at two resonating frequencies in the frequency range from 1 GHz to 4 GHz depending on the geometric specifications of SSRR, strip line, radiating patch, and feed location point. Proposed antenna provides good return loss behavior at both resonating frequencies. The obtained VSWR at both resonating frequencies is very much near to 1. Proposed antenna covers applications in mobile communication and Wi-MAX. Proposed patch antenna is compared with the conventional patch antenna, which shows the significant miniaturization as compared to conventional patch antenna.

This paper introduces a traffic load and interference based bandwidth allocation (TLIBA) scheme for wireless mesh network (WMN) that improves the delay and throughput performance by proper utilization of assigned bandwidth. The bandwidth is allocated based jointly on traffic load and interference. Then a suitable path is selected based upon the least routing metric (RM) value. Simulation results are presented to demonstrate the effectiveness of the proposed approach which indicates higher bandwidth utilization and throughput as compared with existing fair end-to-end bandwidth allocation (FEBA).

In the current study a meshfree Lagrangian particle method for the Landau-Lifshitz Navier-Stokes (LLNS) equations is developed. The LLNS equations incorporate thermal fluctuation into macroscopic hydrodynamics by the addition of white noise fluxes whose magnitudes are set by a fluctuation-dissipation theorem. The study focuses on capturing the correct variance and correlations computed at equilibrium flows, which are compared with available theoretical values. Moreover, a numerical test for the random walk of standing shock wave has been considered for capturing the shock location., 17 pages, 2 figures

The FinFETs recently have been the rallying point for the engineers as far as the development of the technology is concerned. The authors here have tried successfully to compare the performance of 30 nm conventional triple gate (Conv) FinFET structure with that of partially cylindrical (PC) FinFET. In PC-FinFET the fin is divided into two regions. Region I is partially cylindrical and has curvature of half of the fin width, and Region II is like a conventional FinFET (having flat region). The results show that there is considerable improvement in Ion, Ioff, and subsequent suppression of short channel effects, that is, subthreshold slope, DIBL, self heating effect, and so forth. The improvement has also been felt in series resistance in PC-FinFET as compared to C-FinFET. It is noteworthy also to mention that in PC-FinFET the corner of fin is rounded thus reducing the side wall area which further reduces the gate capacitance reducing the intrinsic delay. The DC and transient analysis of CMOS inverter using C-FinFET and PC-FinFET have been done which shows that PC-FinFET inverter has reduced propagation delay as compared to C-FinFET.

This paper presents a comparative study of high-speed and low-voltage full adder circuits. Our approach is based on hybrid design full adder circuits combined in a single unit. A high performance adder cell using an XOR-XNOR (3T) design style is discussed. This paper also discusses a high-speed conventional full adder design combined with MOSCAP Majority function circuit in one unit to implement a hybrid full adder circuit. Moreover, it presents low-power Majority-function-based 1-bit full addersthat use MOS capacitors (MOSCAP) in its structure. This technique helps in reducing power consumption, propagation delay, and area of digital circuits while maintaining low complexity of logic design. Simulation results illustrate the superiority of the designed adder circuits over the conventional CMOS, TG, and hybrid adder circuits in terms of power, delay, power delay product (PDP), and energy delay product (EDP). Postlayout simulation results illustrate the superiority of the newly designed majority adder circuits against the reported conventional adder circuits. The design is implemented on UMC 0.18 m process models in Cadence Virtuoso Schematic Composer at 1.8 V single-ended supply voltage, and simulations are carried out on Spectre S.

We consider a self-propelled interacting particle system for the collective behavior of swarms of animals, and extend it with an attraction term called roosting force, as it has been suggested in Ref. 30. This new force models the tendency of birds to overfly a fixed preferred location, e.g. a nest or a food source. We include roosting to the existing individual-based model and consider the associated mean-field and hydrodynamic equations. The resulting equations are investigated analytically looking at different asymptotic limits of the corresponding stochastic model. In addition to existing patterns like single mills, the inclusion of roosting yields new scenarios of collective behavior, which we study numerically on the microscopic as well as on the hydrodynamic level.

A small-scale, trapezoidal rigid body in the gas-filled gap between two parallel plates at different temperatures is considered. An analytical expression for the thermally induced force onto the body in the direction parallel to the plates valid for an infinite Knudsen number is derived. For this purpose, diffuse reflection of the gas molecules at the solid walls is assumed. Simultaneously, Monte Carlo simulations are performed allowing an extension of the analysis to Knudsen numbers of the order of one. The numerical and the analytical results show excellent agreement, indicating that a temperature gradient orthogonal to the plates can induce a significant force in parallel direction, a phenomenon without analogy in the macroworld. This force is only slightly reduced when a Knudsen number of one is considered. In addition to the diffuse-reflection boundary condition, a mixture of diffuse and specular reflection is studied. The practical relevance of the results is exemplified by considering two scenarios with bodies of a specific geometry, among others a nanoscopic platelet.

A meshfree particle method is used to simulate free surface flows. This is a Lagrangian method. Flows are modeled by the incompressible Navier-Stokes equations. The particle projection method is used to solve the Navier-Stokes equations. The spatial derivatives are approximated by the weighted least squares method (WLS). The pressure Poisson equation is solved by a local iterative procedure with the help of WLS. Numerical experiments are presented for two dimensional cases. In the case of breaking dam problem the numerical result is compared with the experimental result. The surface tension effects are studied in different shapes of drops and Laplace's law is verified. Finally, the collisions of two drops are simulated.

In this paper we present a domain decomposition approach for the coupling of Boltzmann and Euler equations. Particle methods are used for both equations. This leads to a simple implementation of the coupling procedure and to natural interface conditions between the two domains. Adaptive time and space discretizations and a direct coupling procedure lead to considerable gains in CPU time compared to a solution of the full Boltzmann equation. Several test cases involving a large range of Knudsen numbers are numerically investigated.

A meshfree method for two-phase immiscible incompressible flows including surface tension is presented. The continuum surface force (CSF) model is used to include the surface tension force. The incompressible Navier–Stokes equation is considered as the mathematical model. Application of implicit projection method results in linear second-order partial differential equations for velocities and pressure. These equations are then solved by the finite pointset method (FPM), which is a meshfree and Lagrangian method. The fluid is represented as finite number of particles and the immiscible fluids are distinguished by the color of each particle. The interface is tracked automatically by advecting the color functions for each particle. Two test cases, Laplace's law and the Rayleigh–Taylor instability in 2D have been presented. The results are found to be consistent with the theoretical results.