An empirical resistance equation for the modelling of corona discharge in saline water

2021 ◽  
Author(s):  
Vitaliy Stelmashuk ◽  
Jiri Schmidt
Keyword(s):  
Numerical Simulations ◽  
Corona Discharge ◽  
Power Function ◽  
Empirical Model ◽  
Wall Motion ◽  
Saline Water ◽  
Experimental Results ◽  
Hydrodynamic Equations ◽  
Resistance Equation ◽  
Good Agreement

Abstract We present a study that was undertaken to calculate the resistance of low current corona discharge in saline water. A novel empirical model was obtained, based on several assumptions, which allowed us to determine the corona resistance using the measured current. This resistance could be then exploited to compute the power deposited to the corona as a function of time. The wall motion of a bubble freely oscillating in saline water was calculated using hydrodynamic equations and the calculated power function. A comparison of numerical simulations with experimental results showed that good agreement was achieved.

scholarly journals Numerical Simulations of V-Shaped Plates Subjected to Blast Loadings: A Validation Study

2016 ◽  
Vol 10 (11) ◽  
pp. 203
Author(s):  
Mohd Zaid Othman ◽  
Qasim H. Shah ◽  
Muhammad Akram Muhammad Khan ◽  
Tan Kean Sheng ◽  
M. A. Yahaya ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Variable Mass ◽  
Blast Loading ◽  
Experimental Results ◽  
Average Difference ◽  
Simulation Results ◽  
Blast Loadings ◽  
Carrier Vehicle ◽  
Good Agreement

A series of numerical simulations utilizing LS-DYNA was performed to determine the mid-point deformations of V-shaped plates due to blast loading. The numerical simulation results were then compared with experimental results from published literature. The V-shaped plate is made of DOMEX 700 and is used underneath an armour personal carrier vehicle as an anti-tank mine to mitigate the effects of explosion from landmines in a battlefield. The performed numerical simulations of blast loading of V-shaped plates consisted of various angles i.e. 60°, 90°, 120°, 150° and 180°; variable mass of explosives located at the central mid-point of the V-shaped vertex with various stand-off distances. It could be seen that the numerical simulations produced good agreement with the experimental results where the average difference was about 26.6%.

scholarly journals Optical turbulence and spectral condensate in long fibre lasers

2012 ◽  
Vol 468 (2145) ◽  
pp. 2496-2508 ◽  
Author(s):  
E. G. Turitsyna ◽  
Gregory Falkovich ◽  
Atalla El-Taher ◽  
Xuewen Shu ◽  
Paul Harper ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Intermediate State ◽  
Experimental Results ◽  
Fibre Laser ◽  
Optical Turbulence ◽  
Fibre Lasers ◽  
Sharp Transition ◽  
Narrow Spectrum ◽  
Good Agreement

We study numerically optical turbulence using the particular example of a recently created, ultra-long fibre laser. For normal fibre dispersion, we observed an intermediate state with an extremely narrow spectrum (condensate), which experiences instability and a sharp transition to a fluctuating regime with a wider spectrum. We demonstrate that the number of modes has an impact on the condensate's lifetime. The smaller the number of modes, the more resistant is the condensate to perturbations. Experimental results show a good agreement with numerical simulations.

scholarly journals Assessment of different turbulence models in simulating axisymmetric flow in suddenly expanded nozzles

2018 ◽  
Vol 7 (3.29) ◽  
pp. 243
Author(s):  
Sher Afghan Khan ◽  
Mir Owais Ali ◽  
Miah Mohammed Riyadh ◽  
Zahid Hossen ◽  
Nafis Mahdi Arefin
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Mach Number ◽  
Numerical Simulations ◽  
Axisymmetric Flow ◽  
Turbulence Models ◽  
Experimental Results ◽  
Nozzle Flow ◽  
Axisymmetric Nozzle ◽  
Good Agreement

A numerical simulation was carried out to compare various turbulence models simulating axisymmetric nozzle flow past suddenly expanded ducts. The simulations were done for L/D = 10. The convergent-divergent nozzle has been modeled and simulated using the turbulence models: The Standard k-ε model, The Standard k-ω model and The SST k-ω model. Numerical simulations were done for Mach numbers 1.87, 2.2, and 2.58 and the nozzles were operated for NPRs in the range from 3 to 11. From the numerical analysis it is apparent that for a given Mach number and effect of NPR will result in maximum gain or loss of pressure. Numerical results are in good agreement with the experimental results.  

Electrical Resistivity Characterization and Modeling of Carbon Nanofiber-Polymer Suspension

2006 ◽  
Author(s):  
Kuang-Ting Hsiao ◽  
Peter Gadalla ◽  
Francis M. Donovan
Keyword(s):  
Electrical Resistivity ◽  
Empirical Model ◽  
Carbon Nanofiber ◽  
Weight Fraction ◽  
Experimental Results ◽  
Model Predictions ◽  
Electrical Resistivities ◽  
Thermal And Electrical Properties ◽  
Dc Sensor ◽  
Good Agreement

Carbon nanofibers (CNFs) and carbon nanotubes (CNTs) are considered as potential fillers for improving the mechanical, thermal, and electrical properties of polymer and polymer composites. One of the applications is to enhance the electrical conductivity of polymer by using CNFs as fillers. This kind of treatment will be useful in the situations where electrostatic dissipation capability of the polymer part is important. This paper presents an investigation of the electrical resistivities of CNF/polymer suspensions of different CNF concentrations, i.e., 2.0wt%, 3.0wt%, 4.5wt%, and 6.0wt%. For determining the electrical resistivities of the CNF/polymer suspensions, a DC-sensor was constructed and used in the experiments. The experimental results indicate that the electrical resistivity of the CNF-polyester suspension decreases as CNF weight fraction increases. In addition, the results show a dramatic decrease of the resistivity when the measurement time prolongs. An empirical model to predict the electrical resistivity evolution of the CNF/polyester suspension was proposed in this paper. Good agreement between the empirical model predictions and the experimental results was found.

Nanoindentation on a Ni Nanodot-Patterned Surface

2008 ◽  
Author(s):  
Hengyu Wang ◽  
Min Zou ◽  
Robert L. Jackson ◽  
Preston R. Larson ◽  
Matthew B. Johnson
Keyword(s):  
Finite Element ◽  
Numerical Simulations ◽  
Experimental Results ◽  
Spherical Contact ◽  
Patterned Surface ◽  
Size And Shape ◽  
Ordered Arrays ◽  
Simulation Results ◽  
Good Agreement

Nanoindentation on a Ni nanodot-patterned surface (NDPS) was investigated experimentally and numerically. The Ni NDPS consists of well-ordered arrays of Ni nanodots with approximately the same size and shape. The nanoindentation experiments were performed on the Ni NDPS using diamond tips of 1 and 5 μm radii of curvature. To efficiently simulate large number of nanodots in contact, numerical simulations were carried out using formulae empirically fitted from a finite element (FE) study of a single spherical contact. The simulation results were found to be in good agreement with the experimental results.

Numerical simulations of stratified inviscid flow over a smooth obstacle

1994 ◽  
Vol 260 ◽  
pp. 1-22 ◽  
Author(s):  
Kevin G. Lamb
Keyword(s):  
Numerical Simulations ◽  
Wave Breaking ◽  
Finite Depth ◽  
Inviscid Flow ◽  
Wave Drag ◽  
Experimental Results ◽  
Buoyancy Frequency ◽  
Lee Waves ◽  
Boussinesq Fluid ◽  
Good Agreement

Results of numerical simulations of the flow of a non-rotating, inviscid, Boussinesq fluid over smooth two-dimensional obstacles are described. The fluid has finite depth and a rigid lid. Far upstream of the obstacle the horizontal velocity and buoyancy frequency are uniform. Comparisons with linear theory for small-amplitude obstacles are made and the long-time behaviour is compared with steady-state Long's model solutions. Comparisons with the time-dependent results of Baines (1979) are done. For Froude numbers between ½ and 1 the obstacle amplitude is varied in order to determine the amplitudes needed to initiate wave breaking. These results are compared with the predictions of Long's model and with the experimental results of Baines (1977) showing good agreement with the latter. It is found that wave breaking occurs for amplitudes significantly lower than Long's model predicts for a large range of Froude numbers. This is shown to be the result of the generation of large-amplitude lee waves with wavelengths longer than that of stationary lee waves, but not long enough to propagate upstream. The behaviour of these waves is coupled to the generation of both longer mode-one waves which do propagate upstream from the obstacle and to mode-two waves which propagate against the flow as they are advected downstream. It is also coupled to oscillations in the wave drag. The periods of the wave drag oscillations are compared to experimental results showing good agreement with cases for which oscillations have been observed. The behaviour of these large transient lee waves is compared with the theoretical results contained in Grimshaw & Yi (1991), showing some similarities. As the Froude number approaches 0.5 the breaking behaviour is no longer due to these large waves, with the result that wave breaking occurs much later.

scholarly journals On the process of Mach wave generation in air

1991 ◽  
Vol 9 (2) ◽  
pp. 453-464 ◽  
Author(s):  
M. De Rosa ◽  
F. Famá ◽  
V. Palleschi ◽  
A. Salvetti ◽  
D. P. Singh ◽  
...  
Keyword(s):  
Wave Generation ◽  
Experimental Results ◽  
Hydrodynamic Equations ◽  
Similar Model ◽  
Perfect Gas ◽  
Mach Wave ◽  
Self Similar ◽  
Strong Explosion ◽  
Good Agreement

The process of Mach wave generation in air is studied in both plane and spherical geometries. The experimental results reported here are theoretically interpreted using the predictions of a self-similar model of strong explosion along with the hydrodynamic equations of a perfect gas, and a good agreement is found.

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

PHOTOINDUCED NONLINEAR OCTUPOLAR POLARIZATION: TRANSIENT AND PERMANENT REGIMES

1996 ◽  
Vol 05 (04) ◽  
pp. 653-670 ◽  
Author(s):  
CÉLINE FIORINI ◽  
JEAN-MICHEL NUNZI ◽  
FABRICE CHARRA ◽  
IFOR D.W. SAMUEL ◽  
JOSEPH ZYSS
Keyword(s):  
Theoretical Analysis ◽  
Second Harmonic ◽  
Experimental Results ◽  
Polar Field ◽  
Rotational Spectrum ◽  
Dual Frequency ◽  
One Dimensional ◽  
Ethyl Violet ◽  
Disperse Red 1 ◽  
Good Agreement

An original poling method using purely optical means and based on a dual-frequency interference process is presented. We show that the coherent superposition of two beams at fundamental and second-harmonic frequencies results in a polar field with an irreducible rotational spectrum containing both a vector and an octupolar component. This enables the method to be applied even to molecules without a permanent dipole such as octupolar molecules. After a theoretical analysis of the process, we describe different experiments aiming at light-induced noncentrosymmetry performed respectively on one-dimensional Disperse Red 1 and octupolar Ethyl Violet molecules. Macroscopic octupolar patterning of the induced order is demonstrated in both transient and permanent regimes. Experimental results show good agreement with theory.

scholarly journals Comparison of Experimental and Numerical Transient Drop Deformation during Transition through Orifices in High-Pressure Homogenizers

2021 ◽  
Vol 5 (3) ◽  
pp. 32
Author(s):  
Benedikt Mutsch ◽  
Peter Walzel ◽  
Christian J. Kähler
Keyword(s):  
High Pressure ◽  
Visual Analysis ◽  
Imaging Technique ◽  
Extensional Flow ◽  
Droplet Breakup ◽  
Experimental Results ◽  
Drop Deformation ◽  
Droplet Deformation ◽  
Shadow Imaging ◽  
Good Agreement

The droplet deformation in dispersing units of high-pressure homogenizers (HPH) is examined experimentally and numerically. Due to the small size of common homogenizer nozzles, the visual analysis of the transient droplet generation is usually not possible. Therefore, a scaled setup was used. The droplet deformation was determined quantitatively by using a shadow imaging technique. It is shown that the influence of transient stresses on the droplets caused by laminar extensional flow upstream the orifice is highly relevant for the droplet breakup behind the nozzle. Classical approaches based on an equilibrium assumption on the other side are not adequate to explain the observed droplet distributions. Based on the experimental results, a relationship from the literature with numerical simulations adopting different models are used to determine the transient droplet deformation during transition through orifices. It is shown that numerical and experimental results are in fairly good agreement at limited settings. It can be concluded that a scaled apparatus is well suited to estimate the transient droplet formation up to the outlet of the orifice.

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