Exploring the Optimality of a Limited View Angle in the Two-Dimensional Vicsek Model

2018 ◽  
Author(s):  
Masoud Jahromi Shirazi ◽  
Nicole Abaid
Keyword(s):  
Numerical Simulation ◽  
Collective Behavior ◽  
Particle Interaction ◽  
Simple Algorithm ◽  
Mathematical Tool ◽  
Two Dimensional ◽  
Engineering Applications ◽  
Vicsek Model ◽  
Natural Systems ◽  
Interaction Dynamics

Collective behavior emerges from local interactions in a group, has been observed in many natural systems, and is of significant interests for engineering applications. The Vicsek model is a mathematical tool to study collective alignment in a group of self-propelled particles based on local interaction, which has been well-studied in the literature for its simple algorithm and complex global behaviors. Several studies show that particles reach alignment faster when the directionality of particle interaction is restricted by an optimal view angle. This result seems counterintuitive, since each particle is expected to get more information through omnidirectional interaction. This work seeks to explore the possible causes of this optimal view angle by studying interaction dynamics in Vicsek model with restricted view angle through numerical simulation.

Comparing the Effects of Intrinsic and Extrinsic Noise on the Vicsek Model in Three Dimensions

2017 ◽  
Author(s):  
Masoud Jahromi Shirazi ◽  
Nicole Abaid
Keyword(s):  
Collective Behavior ◽  
Intrinsic Noise ◽  
Three Dimensions ◽  
Extrinsic Noise ◽  
Vicsek Model ◽  
Fish Schools ◽  
Natural Systems ◽  
Order And Disorder ◽  
Noise Models ◽  
Intrinsic And Extrinsic Noise

A group of simple individuals may show ordered, complex behavior through local interactions. This phenomenon is called collective behavior, which has been observed in a vast variety of natural systems such as fish schools or bird flocks. The Vicsek model is a well-established mathematical model to study collective behavior through interaction of individuals with their neighbors in the presence of noise. How noise is modeled can impact the collective behavior of the group. Extrinsic noise captures uncertainty imposed on individuals, such as noise in measurements, while intrinsic noise models uncertainty inherent to individuals, akin to free will. In this paper, the effects of intrinsic and extrinsic noise on characteristics of the transition between order and disorder in the Vicsek model in three dimensions are studied through numerical simulation.

Numerical Simulation of the Performance of a Sudden Expansion With Fence Viewed as a Diffuser in Low Reynolds Number Regime

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
S. Chakrabarti ◽  
S. Rao ◽  
D. K. Mandal
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Aspect Ratio ◽  
Diffusion Process ◽  
Static Pressure ◽  
Low Reynolds Number ◽  
Simple Algorithm ◽  
Sudden Expansion ◽  
Two Dimensional ◽  
Low Reynolds

In this paper, the results of numerical simulation on the performance of a sudden expansion with fence viewed as a diffuser are presented. The two-dimensional steady differential equations for conservation of mass and momentum have been solved using the semi-implicit method for pressure-linked equations (SIMPLE) algorithm. The Reynolds number is in the range of 20–100 and fence subtended angle (FSA) between 10 deg and 30 deg. An aspect ratio of 2 is fixed for all the computations. The effect of each variable on average static pressure and diffuser effectiveness has been studied. Computations have revealed that for higher Reynolds number, the use of a fence always increases the effectiveness of the diffusion process when compared with a simple sudden expansion configuration. In low Reynolds number regime, depending on the positioning of the fence and the fence subtended angle, the fence may increase or decrease the diffuser effectiveness in comparison with sudden expansion without fence.

scholarly journals Study on X-ray Induced Two-Dimensional Thermal Shock Waves in Carbon/Phenolic

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3553
Author(s):  
Dengwang Wang ◽  
Yong Gao ◽  
Sheng Wang ◽  
Jie Wang ◽  
Haipeng Li
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Wave Propagation ◽  
Thermal Shock ◽  
Anisotropic Material ◽  
Energy Deposition ◽  
X Rays ◽  
Two Dimensional ◽  
X Ray ◽  
Deposition Depth

Carbon/Phenolic (C/P), a typical anisotropic material, is an important component of aerospace and often used to protect the thermodynamic effects of strong X-ray radiation. In this paper, we establish the anisotropic elastic-plastic constitutive model, which is embedded in the in-house code “RAMA” to simulate a two-dimensional thermal shock wave induced by X-ray. Then, we compare the numerical simulation results with the thermal shock wave stress generated by the same strong current electron beam via experiment to verify the correctness of the numerical simulation. Subsequently, we discuss and analyze the rules of thermal shock wave propagation in C/P material by further numerical simulation. The results reveal that the thermal shock wave represents different shapes and mechanisms by the radiation of 1 keV and 3 keV X-rays. The vaporization recoil phenomenon appears as a compression wave under 1 keV X-ray irradiation, and X-ray penetration is caused by thermal deformation under 3 keV X-ray irradiation. The thermal shock wave propagation exhibits two-dimensional characteristics, the energy deposition of 1 keV and 3 keV both decays exponentially, the energy deposition of 1 keV-peak soft X-ray is high, and the deposition depth is shallow, while the energy deposition of 3 keV-peak hard X-ray is low, and the deposition depth is deep. RAMA can successfully realize two-dimensional orthotropic elastoplastic constitutive relation, the corresponding program was designed and checked, and the calculation results for inspection are consistent with the theory. This study has great significance in the evaluation of anisotropic material protection under the radiation of intense X-rays.

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