Numerical study on partial discharge in a dry air cavity with a two-dimensional fluid model considering practical reactions

This paper presents a three-dimensional unsteady numerical simulation of a turbulent plunging liquid jet without artificial surface disturbance impinging on a quiecent liquid pool. The focal point of the study is the initial impact and air entrainment process. The multiphase, Volume of Fluid Model is used in combination with the Reynolds Averaged k-ε turbulence model. The process of the initial impact of the jet on the free surface, the subsequent formation of an air cavity and the subsequent break-down of the cavity into small bubbles are captued and analyzed. These simulations show clearly and in detail the process of air carryunder by the liquid-liquid jet. The air cavity caused by the intial jet impact stretches deeply under the pool surface untill break down due to the shear created by a torroidal vortex. The predicted maximum height of the developing air cavity shows very good agreement with existing semi-empirical correlations from the literature and experiments. The velocity of the front of the air cavity is equal to about half the jet valocity at impact as shown by previous works and the predicted penetration depth shows acceptable agreement with previous correlations. The VOF model shows a strong capability of tracking the interface between two phases.

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Two-Dimensional Numerical Study on Characterization of Low-Pressure Capacitively Coupled Argon Discharges

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.556-562.1691 ◽

2014 ◽

Vol 556-562 ◽

pp. 1691-1695

Author(s):

Ya Chun Zhang ◽

Xiang He ◽

Jian Pin Chen ◽

Xiao Wu Ni ◽

Jian Lu ◽

...

Keyword(s):

Numerical Study ◽

Fluid Model ◽

Low Pressure ◽

Two Dimensional ◽

Capacitively Coupled ◽

Positive Ions ◽

Cell Reactor ◽

Reactor Type ◽

Gaseous Electronics Conference

This paper presents an investigation of argon capacitively coupled plasma at low pressure. A two-dimensional, time-dependent fluid model is used to describe the production, transport, and destruction of electrons and positive ions. The model is solved for a GEC(gaseous electronics conference) Cell reactor type (with 4cm diameter and 2.5cm interelectrode distance) operating at frequency 13.56MHz, pressure 1Torr and applied voltage 1000V, in pure argon. Two-dimensional distributions are presented in the stationary state, including electron temperature and species density i.e. electron, ion and metastable atom. The electric field and electric potential at different phases in one RF cycle is also studied.

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A numerical study of flame growth in two-dimensional mixing layers

10.2514/6.1994-783 ◽

1994 ◽

Author(s):

S. Noda ◽

T. Nakajima ◽

K. Hashimoto

Keyword(s):

Numerical Study ◽

Mixing Layers ◽

Two Dimensional

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Numerical Study on Two-dimensional Magnetic Photonic Crystals Made of Magnetized Ferrites

PIERS Online ◽

10.2529/piers060906233818 ◽

2007 ◽

Vol 3 (3) ◽

pp. 305-307 ◽

Cited By ~ 1

Author(s):

Jie Xu ◽

Ping Chen ◽

Yue Shi ◽

Xin-Yi Ji ◽

Ai-Min Jiang ◽

...

Keyword(s):

Photonic Crystals ◽

Numerical Study ◽

Two Dimensional ◽

Magnetic Photonic Crystals

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Co-planar two-dimensional Metal-Insulator-Semiconductor Capacitor: Numerical study of the device electrostatics.

10.26434/chemrxiv.5398000 ◽

2017 ◽

Author(s):

Varun Bheemireddy

Keyword(s):

Space Charge ◽

High Performance ◽

Numerical Study ◽

2D Materials ◽

Space Charge Density ◽

Two Dimensional ◽

Short Channel ◽

Metal Insulator ◽

Metal Insulator Semiconductor ◽

New Family

The two-dimensional(2D) materials are highly promising candidates to realise elegant and e cient transistor. In the present letter, we conjecture a novel co-planar metal-insulator-semiconductor(MIS) device(capacitor) completely based on lateral 2D materials architecture and perform numerical study of the capacitor with a particular emphasis on its di erences with the conventional 3D MIS electrostatics. The space-charge density features a long charge-tail extending into the bulk of the semiconductor as opposed to the rapid decay in 3D capacitor. Equivalently, total space-charge and semiconductor capacitance densities are atleast an order of magnitude more in 2D semiconductor. In contrast to the bulk capacitor, expansion of maximum depletion width in 2D semiconductor is observed with increasing doping concentration due to lower electrostatic screening. The heuristic approach of performance analysis(2D vs 3D) for digital-logic transistor suggest higher ON-OFF current ratio in the long-channel limit even without third dimension and considerable room to maximise the performance of short-channel transistor. The present results could potentially trigger the exploration of new family of co-planar at transistors that could play a signi significant role in the future low-power and/or high performance electronics.<br>

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Model of thermal buoyancy in cavity-ventilated roof constructions

Journal of Building Physics ◽

10.1177/1744259120984189 ◽

2021 ◽

pp. 174425912098418

Author(s):

Toivo Säwén ◽

Martina Stockhaus ◽

Carl-Eric Hagentoft ◽

Nora Schjøth Bunkholt ◽

Paula Wahlgren

Keyword(s):

Analytical Model ◽

Flow Rate ◽

Numerical Study ◽

Air Flow ◽

Wind Pressure ◽

Air Flow Rate ◽

Test Set ◽

Air Cavity ◽

Thermal Buoyancy ◽

The Impact

Timber roof constructions are commonly ventilated through an air cavity beneath the roof sheathing in order to remove heat and moisture from the construction. The driving forces for this ventilation are wind pressure and thermal buoyancy. The wind driven ventilation has been studied extensively, while models for predicting buoyant flow are less developed. In the present study, a novel analytical model is presented to predict the air flow caused by thermal buoyancy in a ventilated roof construction. The model provides means to calculate the cavity Rayleigh number for the roof construction, which is then correlated with the air flow rate. The model predictions are compared to the results of an experimental and a numerical study examining the effect of different cavity designs and inclinations on the air flow rate in a ventilated roof subjected to varying heat loads. Over 80 different test set-ups, the analytical model was found to replicate both experimental and numerical results within an acceptable margin. The effect of an increased total roof height, air cavity height and solar heat load for a given construction is an increased air flow rate through the air cavity. On average, the analytical model predicts a 3% higher air flow rate than found in the numerical study, and a 20% lower air flow rate than found in the experimental study, for comparable test set-ups. The model provided can be used to predict the air flow rate in cavities of varying design, and to quantify the impact of suggested roof design changes. The result can be used as a basis for estimating the moisture safety of a roof construction.

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A numerical study of gravity-driven instability in strongly coupled dusty plasma. Part 1. Rayleigh–Taylor instability and buoyancy-driven instability

Journal of Plasma Physics ◽

10.1017/s0022377821000349 ◽

2021 ◽

Vol 87 (2) ◽

Author(s):

Vikram S. Dharodi ◽

Amita Das

Keyword(s):

Dusty Plasma ◽

Numerical Study ◽

Fluid Model ◽

Density Region ◽

Strongly Coupled ◽

Rising Bubble ◽

Inhomogeneous Density ◽

Gravity Driven ◽

The Individual ◽

Strongly Coupled Dusty Plasma

Rayleigh–Taylor (RT) and buoyancy-driven (BD) instabilities are driven by gravity in a fluid system with inhomogeneous density. The paper investigates these instabilities for a strongly coupled dusty plasma medium. This medium has been represented here in the framework of the generalized hydrodynamics (GHD) fluid model which treats it as a viscoelastic medium. The incompressible limit of the GHD model is considered here. The RT instability is explored both for gradual and sharp density gradients stratified against gravity. The BD instability is discussed by studying the evolution of a rising bubble (a localized low-density region) and a falling droplet (a localized high-density region) in the presence of gravity. Since both the rising bubble and falling droplet have symmetry in spatial distribution, we observe that a falling droplet process is equivalent to a rising bubble. We also find that both the gravity-driven instabilities get suppressed with increasing coupling strength of the medium. These observations have been illustrated analytically as well as by carrying out two-dimensional nonlinear simulations. Part 2 of this paper is planned to extend the present study of the individual evolution of a bubble and a droplet to their combined evolution in order to understand the interaction between them.

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