scholarly journals Active fluidization in dense glassy systems

Soft Matter ◽  
2016 ◽  
Vol 12 (29) ◽  
pp. 6268-6276 ◽  
Author(s):  
Rituparno Mandal ◽  
Pranab Jyoti Bhuyan ◽  
Madan Rao ◽  
Chandan Dasgupta
Keyword(s):  
Numerical Simulations ◽  
Low Temperatures ◽  
Glass Phase ◽  
Critical Value ◽  
Soft Glass ◽  
Glassy Systems ◽  
Soft Glasses

Dense soft glasses show strong collective caging behavior at sufficiently low temperatures. Using numerical simulations, we show that the introduction of activity can induce cage breaking and fluidization in a model of soft glass. The glass phase disappears beyond a critical value of the activity.

Numerical Simulations of Electric Field Driven Self-Assembly of Monolayers of Mixtures of Nanoparticles

2017 ◽  
Author(s):  
E. Amah ◽  
N. Musunuri ◽  
Ian S. Fischer ◽  
Pushpendra Singh
Keyword(s):  
Electric Field ◽  
Physical Properties ◽  
Numerical Simulations ◽  
Self Assembly ◽  
Composite Particle ◽  
Critical Value ◽  
Direct Numerical Simulations ◽  
Composite Particles ◽  
Liquid Interfaces ◽  
Induced Dipole

We numerically study the process of self-assembly of particle mixtures on fluid-liquid interfaces when an electric field is applied in the direction normal to the interface. The force law for the dependence of the electric field induced dipole-dipole and capillary forces on the distance between the particles and their physical properties obtained in an earlier study by performing direct numerical simulations is used for conducting simulations. The inter-particle forces cause mixtures of nanoparticles to self-assemble into molecular-like hierarchical arrangements consisting of composite particles which are organized in a pattern. However, there is a critical electric intensity value below which particles move under the influence of Brownian forces and do not self-assemble. Above the critical value, when the particles sizes differed by a factor of two or more, the composite particle has a larger particle at its core and several smaller particles forming a ring around it. Approximately same sized particles, when their concentrations are approximately equal, form binary particles or chains (analogous to polymeric molecules) in which positively and negatively polarized particles alternate, but when their concentrations differ the particles whose concentration is larger form rings around the particles with smaller concentration.

scholarly journals Buckling of a coated elastic half-space when the coating and substrate have similar material properties

2015 ◽  
Vol 471 (2178) ◽  
pp. 20140979 ◽  
Author(s):  
Y. B. Fu ◽  
P. Ciarletta
Keyword(s):  
Numerical Simulations ◽  
Material Properties ◽  
Deformation Gradient ◽  
Critical Value ◽  
Elastic Half Space ◽  
Similar Material ◽  
Fully Nonlinear ◽  
Shear Moduli ◽  
Subcritical Regime ◽  
Post Buckling

This study investigates the buckling of a uni-axially compressed neo-Hookean thin film bonded to a neo-Hookean substrate. Previous studies have shown that the elastic bifurcation is supercritical if r ≡ μ f / μ s >1.74 and subcritical if r <1.74, where μ f and μ s are the shear moduli of the film and substrate, respectively. Moreover, existing numerical simulations of the fully nonlinear post-buckling behaviour have all been focused on the regime r >1.74. In this paper, we consider instead a subset of the regime r <1.74, namely when r is close to unity. Four near-critical regimes are considered. In particular, it is shown that, when r >1 and the stretch is greater than the critical stretch (the subcritical regime), there exists a localized solution that arises as the limit of modulated periodic solutions with increasingly longer and longer decaying tails. The evolution of each modulated periodic solution is followed as r is decreased, and it is found that there exists a critical value of r at which the deformation gradient develops a discontinuity and the solution becomes a static shock. The semi-analytical results presented could help future numerical simulations of the fully nonlinear post-buckling behaviour.

Dynamics of a stochastic three-species competitive model with Lévy jumps

2018 ◽  
Vol 11 (05) ◽  
pp. 1850075
Author(s):  
Yongxin Gao ◽  
Shiquan Tian
Keyword(s):  
Numerical Simulations ◽  
Critical Value ◽  
Persistence In The Mean ◽  
Competitive Model ◽  
Stability In Distribution ◽  
Parameters Analysis ◽  
The Mean ◽  
Lévy Jumps ◽  
White Noises ◽  
Theoretical Results

This paper is concerned with a three-species competitive model with both white noises and Lévy noises. We first carry out the almost complete parameters analysis for the model and establish the critical value between persistence in the mean and extinction for each species. The sufficient criteria for stability in distribution of solutions are obtained. Finally, numerical simulations are carried out to verify the theoretical results.

scholarly journals A theoretical study of a possible model of paramagnetic alums at low temperatures

1940 ◽  
Vol 176 (965) ◽  
pp. 203-213 ◽  
Keyword(s):  
Magnetic Field ◽  
Low Temperatures ◽  
Theoretical Study ◽  
Spontaneous Magnetization ◽  
Critical Value ◽  
Transition Curve ◽  
Thin Specimen ◽  
First Order ◽  
Freely Suspended ◽  
Line Of Critical Points

An attempt is made to examine theoretically the properties of paramagnetic alums at low temperatures. The model taken is a lattice of freely suspended magnets, all interactions except purely magnetic being neglected. Even with this simplification it is impossible at present to make rigorous calculations of the partition function, either on classical or quantum lines. A simple model is proposed, which is really a generalization of the Bragg - Williams theory enabling one to take account of the effect of a magnetic field. The few configurations whose energies are known are used to fix arbitrary constants in the expression assumed for the energy. The theory predicts that the state of lowest energy is either a spontaneously magnetized, state for a long thin specimen, or a state in which alternate rows of magnets point in opposite directions for a sphere, spontaneous magnetization appearing in an ellipsoid with an eccentricity greater than a certain critical value. The transition curve bounding the region in which the antiparallel state is stable consists partly of a line of Curie points corresponding to transitions of the second, order, passing smoothly into a line of critical points corresponding to a transition of the first order. The effect of shape on the magnetic properties of the specimen seems to be experimentally verified, but the rough nature of the theory prevents it being more than qualitative.

scholarly journals Chaos and Hopf Bifurcation Analysis of the Delayed Local Lengyel-Epstein System

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Qingsong Liu ◽  
Yiping Lin ◽  
Jingnan Cao ◽  
Jinde Cao
Keyword(s):  
Hopf Bifurcation ◽  
Time Delay ◽  
Numerical Simulations ◽  
Bifurcation Analysis ◽  
Center Manifold ◽  
Local Reaction ◽  
Reaction Diffusion ◽  
Critical Value ◽  
Hopf Bifurcations ◽  
The Stability

The local reaction-diffusion Lengyel-Epstein system with delay is investigated. By choosingτas bifurcating parameter, we show that Hopf bifurcations occur when time delay crosses a critical value. Moreover, we derive the equation describing the flow on the center manifold; then we give the formula for determining the direction of the Hopf bifurcation and the stability of bifurcating periodic solutions. Finally, numerical simulations are performed to support the analytical results and the chaotic behaviors are observed.

scholarly journals Turbulent drag reduction by anisotropic permeable substrates – analysis and direct numerical simulations

2019 ◽  
Vol 875 ◽  
pp. 124-172 ◽  
Author(s):  
G. Gómez-de-Segura ◽  
R. García-Mayoral
Keyword(s):  
Drag Reduction ◽  
Numerical Simulations ◽  
Critical Value ◽  
Direct Numerical Simulations ◽  
Mean Flow ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag ◽  
Theoretical Predictions ◽  
The Mean ◽  
The Difference

We explore the ability of anisotropic permeable substrates to reduce turbulent skin friction, studying the influence that these substrates have on the overlying turbulence. For this, we perform direct numerical simulations of channel flows bounded by permeable substrates. The results confirm theoretical predictions, and the resulting drag curves are similar to those of riblets. For small permeabilities, the drag reduction is proportional to the difference between the streamwise and spanwise permeabilities. This linear regime breaks down for a critical value of the wall-normal permeability, beyond which the performance begins to degrade. We observe that the degradation is associated with the appearance of spanwise-coherent structures, attributed to a Kelvin–Helmholtz-like instability of the mean flow. This feature is common to a variety of obstructed flows, and linear stability analysis can be used to predict it. For large permeabilities, these structures become prevalent in the flow, outweighing the drag-reducing effect of slip and eventually leading to an increase of drag. For the substrate configurations considered, the largest drag reduction observed is ${\approx}$20–25 % at a friction Reynolds number $\unicode[STIX]{x1D6FF}^{+}=180$.

scholarly journals Bifurcations and Dynamics of the Rb-E2F Pathway Involving miR449

Complexity ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-20
Author(s):  
Lingling Li ◽  
Jianwei Shen
Keyword(s):  
Steady State ◽  
Hopf Bifurcation ◽  
Time Delay ◽  
Numerical Simulations ◽  
Bifurcation Theory ◽  
Critical Value ◽  
Asymptotically Stable ◽  
Delay Model ◽  
Dynamical Behaviors ◽  
Theoretical Results

We focused on the gene regulative network involving Rb-E2F pathway and microRNAs (miR449) and studied the influence of time delay on the dynamical behaviors of Rb-E2F pathway by using Hopf bifurcation theory. It is shown that under certain assumptions the steady state of the delay model is asymptotically stable for all delay values; there is a critical value under another set of conditions; the steady state is stable when the time delay is less than the critical value, while the steady state is changed to be unstable when the time delay is greater than the critical value. Thus, Hopf bifurcation appears at the steady state when the delay passes through the critical value. Numerical simulations were presented to illustrate the theoretical results.

scholarly journals Precursors of fluidisation in the creep response of a soft glass

Soft Matter ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 415-423 ◽  
Author(s):  
Raffaela Cabriolu ◽  
Jürgen Horbach ◽  
Pinaki Chaudhuri ◽  
Kirsten Martens
Keyword(s):  
Shear Stress ◽  
Numerical Simulations ◽  
Amorphous Materials ◽  
Three Dimensional ◽  
Creep Response ◽  
Soft Glass ◽  
Glass Model ◽  
Colloidal Glass

Viaextensive numerical simulations, we study the fluidisation process of dense amorphous materials subjected to an external shear stress, using a three-dimensional colloidal glass model.

Persistence and extinction of a stochastic delay predator-prey model in a polluted environment

2016 ◽  
Vol 66 (1) ◽  
Author(s):  
Zhenhai Liu ◽  
Qun Liu
Keyword(s):  
Numerical Simulations ◽  
Critical Value ◽  
Polluted Environment ◽  
Stochastic Delay ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Prey Model ◽  
Persistence In The Mean ◽  
The Mean

AbstractIn this paper, we study a stochastic delay predator-prey model in a polluted environment. Sufficient criteria for extinction and non-persistence in the mean of the model are obtained. The critical value between persistence and extinction is also derived for each population. Finally, some numerical simulations are provided to support our main results.

Effects of Topography on Baroclinic Instability

2013 ◽  
Vol 43 (4) ◽  
pp. 790-804 ◽  
Author(s):  
Changheng Chen ◽  
Igor Kamenkovich
Keyword(s):  
Numerical Model ◽  
Numerical Simulations ◽  
Potential Vorticity ◽  
Growth Rates ◽  
Vertical Structure ◽  
Bottom Topography ◽  
Baroclinic Instability ◽  
Critical Value ◽  
Zonal Flows ◽  
Topographic Slope

Abstract The importance of bottom topography in the linear baroclinic instability of zonal flows on the β plane is examined by using analytical calculations and a quasigeostrophic eddy-resolving numerical model. The particular focus is on the effects of a zonal topographic slope, compared with the effects of a meridional slope. A zonal slope always destabilizes background zonal flows that are otherwise stable in the absence of topography regardless of the slope magnitude, whereas the meridional slopes stabilize/destabilize zonal flows only through changing the lower-level background potential vorticity gradient beyond a known critical value. Growth rates, phase speeds, and vertical structure of the growing solutions strongly depend on the slope magnitude. In the numerical simulations configured with an isolated meridional ridge, unstable modes develop on both sides of the ridge and propagate eastward of the ridge, in agreement with analytical results.

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