scholarly journals Transition models from the quenched to ignited states for flows of inertial particles suspended in a simple sheared viscous fluid

2012 ◽  
Vol 711 ◽  
pp. 147-160 ◽  
Author(s):  
J.-F. Parmentier ◽  
O. Simonin
Keyword(s):  
Numerical Simulation ◽  
Viscous Fluid ◽  
Inertial Particles ◽  
Precise Calculation ◽  
Theoretical Predictions ◽  
Dense Flows ◽  
Transition Models ◽  
Simulation Results ◽  
Anisotropy Coefficients ◽  
Good Agreement

AbstractA review of existing theories for flows of inertial particles suspended in an unbounded sheared viscous fluid is presented first. A comparison between theoretical predictions and numerical simulation results is made for Stokes numbers from $1$ to $10$ in dilute and dense flows. Both particle agitation and anisotropy coefficients are examined, showing that neither of them is able to give satisfactory results in dense flows. A more precise calculation of collisional contributions to the balance law of the particle stress tensor is presented. Results of the corresponding theory are in very good agreement with numerical simulations both in dilute and dense flows.

Numerical Simulation on Thixo-Forging of Magnesium Matrix Composite

2011 ◽  
Vol 189-193 ◽  
pp. 2535-2538 ◽  
Author(s):  
Hong Yan ◽  
Wen Xian Huang
Keyword(s):  
Numerical Simulation ◽  
Matrix Composite ◽  
Metal Flow ◽  
Magnesium Matrix Composite ◽  
Magnesium Matrix ◽  
Simulation Based ◽  
Prior Literature ◽  
Simulation Results ◽  
Computer Numerical Simulation ◽  
Good Agreement

The thixo-forging of magnesium matrix composite was analyzed with computer numerical simulation based on rigid viscoplastic finite element method. The constitutive model of SiCp/AZ61 composite was established in our prior literature. Behavior of metal flow and temperature field were obtained. The differences between traditional forging and thixo-forging processes were analyzed. Results indicated that thixo-forging was better in filling cavity than forging. Simulation results were good agreement with experimental ones.

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%.

BIFURCATIONS OF PERIODIC ORBITS IN A JOSEPHSON EQUATION WITH A PHASE SHIFT

2002 ◽  
Vol 12 (07) ◽  
pp. 1515-1530 ◽  
Author(s):  
ZHUJUN JING ◽  
HONGJUN CAO
Keyword(s):  
Numerical Simulation ◽  
Phase Shift ◽  
Periodic Orbits ◽  
Averaging Method ◽  
Melnikov Function ◽  
Second Order ◽  
Constant Current ◽  
Small Perturbations ◽  
Theoretical Predictions ◽  
Simulation Results

The Josephson equation with constant current and sinusoidal forcings and a phase shift is investigated in detail: the existence and the bifurcations of harmonics and subharmonics under small perturbations are given, by using the second-order averaging method and Melnikov function; the influence on bifurcations of periodic or subharmonics as the phase shift varies is considered; some numerical simulation results are reported in order to prove our theoretical predictions.

scholarly journals New test of the dynamic theory of neutron diffraction by a moving grating

2018 ◽  
Vol 177 ◽  
pp. 03005
Author(s):  
Maxim Zakharov ◽  
Alexander Frank ◽  
German Kulin ◽  
Semyon Goryunov
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Neutron Diffraction ◽  
Dynamic Theory ◽  
Time Of Flight ◽  
Dynamical Theory ◽  
Zero Order ◽  
Significant Suppression ◽  
Theoretical Predictions ◽  
Good Agreement

Recently, multiwave dynamical theory of neutron diffraction by a moving grating was developed. The theory predicts that at a certain height of the grating profile a significant suppression of the zero-order diffraction may occur. The experiment to confirm predictions of this theory was performed. The resulting diffracted UCNs spectra were measured using time-of-flight Fourier diffractometer. The experimental data were compared with the results of numerical simulation and were found in a good agreement with theoretical predictions.

Effects of Materials on Formation of Double-Layered Liners Shaped Charges

2009 ◽  
Vol 79-82 ◽  
pp. 1277-1280
Author(s):  
Yu Zheng ◽  
Xiao Ming Wang ◽  
Wen Bin Li ◽  
Wen Jin Yao
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Numerical Simulations ◽  
Double Layer ◽  
Two Dimensional ◽  
Materials Properties ◽  
X Ray ◽  
Dimensional Finite Element ◽  
Simulation Results ◽  
Good Agreement

In order to study the effects of liner materials on the formation of Shaped Charges with Double Layer Liners (SCDLL) into tandem Explosively Formed Projectile (EFP), the formation mechanism of DLSCL was studied. Utilizing two-dimensional finite element dynamic code AUTODYN, the numerical simulations on the mechanical phenomenon of SCDLL forming into tandem EFP were carried out. X-ray pictures were obtained after Experiments on SCDLL. Comparisons between experimental results and numerical simulation results have good agreement. It can be concluded from the results that the materials properties and configurations of both liners are crucial to the formation of tandem EFP.

Numerical Simulation of Machining Distortion of Residually Stressed Aircraft Aluminum Components

2006 ◽  
Vol 315-316 ◽  
pp. 235-238 ◽  
Author(s):  
Q.C. Wang ◽  
Xiao Dong Hu ◽  
W. Li ◽  
Ju Long Yuan
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Energy Density ◽  
Square Root ◽  
Stress Range ◽  
Key Factors ◽  
Machining Distortion ◽  
Simulation Results ◽  
Aluminum Component ◽  
Good Agreement

The presence of residual stress in aircraft aluminum components can give rise to distortion after machining. Excessive distortion may result in the rejection of a part or the need for costly and time-consuming rework prior to placement in service. The purpose of this research was to develop a methodology for the prediction of machining-induced distortions of residually stressed aircraft aluminum components. Numerical simulation results show that the magnitude of machining distortion is strongly related to the square root of Stain Energy Density W or Stress Range σ . The experimental results demonstrate good agreement with the predicted machining distortions of 7075T73 bulkheads. It included that the original residual stress in the blocks of aircraft aluminum component is one of key factors to cause machining distortion.

scholarly journals Effects of Shell on Bore center Annular Shaped Charges Formation and Penetrating into Steel Targets

2020 ◽  
Vol 70 (1) ◽  
pp. 35-40
Author(s):  
Wenlong Xu ◽  
Cheng Wang ◽  
Jianming Yuan ◽  
Weiliang Goh ◽  
Bin Xu
Keyword(s):  
Numerical Simulation ◽  
Radial Velocity ◽  
Numerical Simulations ◽  
Penetration Depth ◽  
Axial Velocity ◽  
Shaped Charge ◽  
Shell Structures ◽  
Steel Shell ◽  
Simulation Results ◽  
Good Agreement

Annular shaped charge can efficiently create large penetration diameter, which can solve the problem of small penetration diameter of a traditional shaped charge, and thus meeting the requirements of large penetration diameter in some specific situations. In this paper, the influence of five kinds shell structures, i.e. no shell, aluminum shell with thickness of 2.0 mm and steel shell with thickness of 2.0 mm, 3.0 mm and 4.0 mm, on bore-center annular shaped charges (BCASCs) formation and penetrating steel targets was investigated by numerical simulations and experiments. The numerical simulation results are in good agreement with the experimental results. The results showed that, from no shell to aluminum shell of 2.0 mm and then to steel shell of 2.0 mm, 3.0 mm and 4.0 mm for BCASCs, the diameter and radial velocity of projectile head decrease, the axial velocity of BCASC projectiles increases gradually, the penetration diameter of the targets decreases, and the penetration depth increases. The penetration diameter caused by the BCASC with no shell is the largest, being 116.0 mm (1.16D), D is the charge diameter. The penetration depth caused by the BCASC with steel shell of 4.0 mm thickness is the deepest, being 76.4 mm (0.76D).

scholarly journals Numerical Simulation Analysis of Cavitation Performance of Tandem Propeller

2018 ◽  
Vol 36 (3) ◽  
pp. 509-515 ◽  
Author(s):  
Xiaoxu Du ◽  
Zhengdong Zhang
Keyword(s):  
Numerical Simulation ◽  
Simulation Analysis ◽  
Cavitation Number ◽  
Hydrodynamic Characteristics ◽  
Turbulent Model ◽  
Cavitation Model ◽  
Cavitation Phenomenon ◽  
Cavitation Performance ◽  
Simulation Results ◽  
Good Agreement

The steady non cavitation hydrodynamic characteristics of CLB4-55-1 tandem propeller and the steady cavitation flows of NACA66 hydrofoil are numerically studied firstly based on the RANS equations of homogeneous multiphase using CFD theory, combined with the SST k-ω turbulent model and Z-G-B cavitation model. Numerical simulation results are in good agreement with the experimental results, which indicates that the numerical method is reliable and accurate. Then, the cavitation performance of the tandem propeller are numerical simulated and analyzed. The results show that the computational model can predict the cavitation performance of tandem propeller accurately. The cavitation performance of tandem propeller is nearly the same as single propeller, however, the cavitation phenomenon of back propeller is greater than the head propeller at certain advance coefficient and cavitation number. The cavitation phenomenon will disappear with the increase of the advance coefficient or the cavitation number.

EVOLVING MODEL OF SCALE-FREE NETWORKS WITH INTRINSIC LINKS

2008 ◽  
Vol 19 (07) ◽  
pp. 1129-1144 ◽  
Author(s):  
XIANMIN GENG ◽  
GUANGHUI WEN ◽  
YING WANG ◽  
JINXIA LI
Keyword(s):  
Numerical Simulation ◽  
Preferential Attachment ◽  
Scaling Exponent ◽  
Scale Free ◽  
Scale Free Networks ◽  
Free Behavior ◽  
Simulation Results ◽  
Evolving Model ◽  
Analytical Expressions ◽  
Good Agreement

In this paper, we introduce the concept of intrinsic link, which is used to describe the intrinsic interactions between the individuals in complex systems. Furthermore, we present a model for the evolution of complex networks, in which the system dynamics motivated by four mechanisms: the addition of new nodes with preferential attachment, the addition of new nodes with intrinsic attachment, the addition of new links with preferential attachment and the addition of new intrinsic links. The model yields scale-free behavior for the degree distributions as confirmed in many real networks. With continumm theory, we get the analytical expressions of the degree distribution and the scaling exponent γ. The analytical expressions are in good agreement with the numerical simulation results.

scholarly journals Computer and Hardware Modeling of Periodically Forcedϕ6-Van der Pol Oscillator

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
A. O. Adelakun ◽  
A. N. Njah ◽  
O. I. Olusola ◽  
S. T. Wara
Keyword(s):  
Numerical Simulation ◽  
Chaotic Dynamics ◽  
Random Number ◽  
Dynamical Behaviour ◽  
Van Der Pol Oscillator ◽  
Secure Communications ◽  
Multiple Time ◽  
Van Der Pol ◽  
Simulation Results ◽  
Good Agreement

Numerical simulation results for the dynamics ofϕ6-systems abound in the literature but their experimental results are yet to be known. This paper presents the chaotic dynamics ofϕ6-Van der Pol oscillator via electronic design, simulation, and hardware implementation. The results obtained are found to be in good agreement with numerical simulation results. The condition for stability of the fixed points is also computed and the method of multiple time scale is used to investigate the dynamical behaviour of the system. Therefore, theϕ6-circuits which have rich dynamics and may have important applications in secure communications, random number generations, cryptography, and so forth have been practically implemented.

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