On the sensitivity of numerical simulations of solidification to the physical properties of the melt and the mould

1987 ◽  
pp. 93-109
Author(s):  
T. J. Smith ◽  
A. F. A. Hoadley ◽  
D. M. Scott
Keyword(s):  
Physical Properties ◽  
Numerical Simulations

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.

Effects of physical properties of the breathing gas on decompression-sickness bubbles

1995 ◽  
Vol 79 (5) ◽  
pp. 1828-1836 ◽  
Author(s):  
M. E. Burkard ◽  
H. D. Van Liew
Keyword(s):  
Partition Coefficient ◽  
Physical Properties ◽  
Numerical Simulations ◽  
Bubble Growth ◽  
Decompression Sickness ◽  
Inert Gases ◽  
Inert Gas ◽  
Half Time ◽  
Bubble Density ◽  
Mathematical Relationships

To explore the relative dangers of different inert gases, we developed mathematical relationships concerned with bubble growth, using equations that separate gas properties from other variables. Predictions for saturation exposures were as follows. 1) Peak volume of a bubble is proportional to solubility in tissue when bubble density is high and to the 3/2 power of the ratio of the permeation coefficient to the partition coefficient when density is low. 2) Bubble duration is inversely proportional to the partition coefficient for the inert gas. 3). Sizes and durations of bubbles for one inert gas relative to another depend on whether the tissue is aqueous or lipid but are independent of the magnitude of the decompression and tissue half time. 4). He should give smaller bubbles than N2, except in aqueous tissue with low bubble density; our prediction correlates qualitatively with relative dangers observed with animals but seems to overestimate the safety afforded by He. Numerical simulations illustrate how nonsaturation dives are less predictable because more variables are involved.

SINGLE-ELECTRON CIRCUITS PERFORMING DENDRITIC PATTERN FORMATION WITH NATURE-INSPIRED CELLULAR AUTOMATA

2007 ◽  
Vol 17 (10) ◽  
pp. 3651-3655 ◽  
Author(s):  
TAKAHIDE OYA ◽  
IKUKO N. MOTOIKE ◽  
TETSUYA ASAI
Keyword(s):  
Pattern Formation ◽  
Cellular Automata ◽  
Physical Properties ◽  
Cellular Automaton ◽  
Numerical Simulations ◽  
Thermal Effects ◽  
Semiconductor Device ◽  
Single Electron ◽  
Dendritic Trees ◽  
Single Electron Devices

We propose a novel semiconductor device in which electronic-analogue dendritic trees grow on multilayer single-electron circuits. A simple cellular-automaton circuit was designed for generating dendritic patterns by utilizing the physical properties of single-electron devices, i.e. quantum and thermal effects in tunneling junctions. We demonstrate typical operations of the proposed circuit through extensive numerical simulations.

Submarine landslide tsunamis in SW Iberia Margin: Sensitivity of tsunamigenic potential and hazard extent to physical properties of marine sediments

2021 ◽  
Author(s):  
Inês Ramalho ◽  
Rachid Omira ◽  
Aldina Piedade ◽  
Davide Gamboa ◽  
José Grazina ◽  
...  
Keyword(s):  
Physical Properties ◽  
Numerical Simulations ◽  
Marine Sediments ◽  
Submarine Landslide ◽  
Slope Instability ◽  
Numerical Code ◽  
Continental Margins ◽  
Iberian Margin ◽  
Landslide Dynamics ◽  
Underwater Landslides

<p>Slope instability is probably the most effective process shaping the seafloor of continental margins. This process often leads to the occurrence of submarine mass failures that, if large enough, can cause potential tsunamis. Yet, the dynamics of the landslide evacuated material and their induced tsunamigenic potential remain largely uncharacterized in most continental margins. This applies to the SW Iberia Margin, where large underwater landslide episodes have been evidenced.</p><p>In this work, we investigate the sensitivity of landslide-generated tsunami to the physical properties of marine sediments involved in the slope failures in the SW Iberia Margin. This includes the landslide dynamics, the tsunamigenic potential and the tsunami hazard extent. Based upon the MAGICLAND (Marine Geo-hazards Induced by Underwater Landslides in the SW Iberian Margin) project database, we select promising sizable submarine landslide scenarios. We then use an in-house developed two-layer numerical code (based on a Bingham visco-plastic model for the landslide and a non-linear shallow water model for the tsunami) to simulate both the landslide dynamics and the induced tsunami generation and propagation.</p><p>In a first stage, the numerical simulations are done considering uncertain sediments properties deduced from the literature. Next, we perform numerical simulations of the selected landslide scenarios using accurate geotechnical properties (mainly the in-situ shear strength obtained from undisturbed samples) determined by laboratory tests conducted on from the analysis of available marine gravity cores in the SW Iberian Margin. Results show that the geotechnical parameters significatively influence the simulation results of both the landslide dynamics and induced tsunami. Particularly, we noticed major effects on the landslide downslope deformation, failure speed, deposited thickness and run-out, which considerably control the momentum transferred to the generated tsunami wave. This demonstrates that the use of inappropriate material properties leads to a misquantification of landslide tsunamigenesis and hazard extent.</p><p>This work was financed by national funds through FCT—Portuguese Foundation for Science and Technology, I.P., under the framework of the project MAGICLAND – Marine Geo-hazards Induced by Underwater Landslides in the SW Iberian Margin (PTDC/ CTA-GEO/30381/2017).</p>

scholarly journals Convective Overshooting: Physical Properties and Seismic Evidence

2002 ◽  
Vol 185 ◽  
pp. 58-69 ◽  
Author(s):  
J.-P. Zahn
Keyword(s):  
High Resolution ◽  
Physical Properties ◽  
Numerical Simulations ◽  
Temperature Profile ◽  
Thermal Diffusion ◽  
Temperature Stratification ◽  
Space Filling ◽  
Acoustic Sounding ◽  
Stable Domain ◽  
Stellar Interiors

AbstractWe review briefly the different prescriptions which have been proposed to predict the extent of convective penetration (or overshoot) in stellar interiors, and we confront them with the results of numerical simulations and with helioseismic data. It appears that the penetrative motions are structured in plumes, and that thermal diffusion plays an important role in controlling the temperature stratification in the stable domain. The most recent high-resolution simulations suggest that these plumes are less space-filling than thought before, and that they are therefore less efficient in establishing an adiabatic temperature profile. This property is compatible with the solar profiles obtained through acoustic sounding.

EFFECT OF SLOPES IN HIGHWAY ON TRAFFIC FLOW

2011 ◽  
Vol 22 (04) ◽  
pp. 319-331 ◽  
Author(s):  
SHIYONG LAN ◽  
YIGUANG LIU ◽  
BINGBING LIU ◽  
PENG SHENG ◽  
TAO WANG ◽  
...  
Keyword(s):  
Physical Properties ◽  
Cellular Automaton ◽  
Numerical Simulations ◽  
Traffic Flow ◽  
Safety Distance ◽  
Ca Model ◽  
Real Traffic

In this paper, we propose a novel slope cellular automaton (CA) model to depict some physical properties of traffic flow with slopes. In our model, we present the effect of slopes on the acceleration/deceleration capabilities and safety distance of the vehicles in highways as in real traffic situations. By numerical simulations, we investigate the dependence of the vehicle capacities in highways on the length and grade of slopes. It is shown that the larger the slope grade, the more significant the effect of slopes on the traffic flow is. Especially when the slope grade is beyond a certain value (i.e. |σ| > 3%), the effect of slopes on traffic flow becomes quite markedly.

scholarly journals Vortex flow properties in simulations of solar plage region: Evidence for their role in chromospheric heating

2020 ◽  
Vol 645 ◽  
pp. A3
Author(s):  
N. Yadav ◽  
R. H. Cameron ◽  
S. K. Solanki
Keyword(s):  
Magnetic Flux ◽  
Physical Properties ◽  
Numerical Simulations ◽  
Solar Atmosphere ◽  
Small Scale ◽  
Flux Tubes ◽  
Current Sheets ◽  
Plage Region ◽  
Magnetic Flux Tubes ◽  
Chromospheric Heating

Context. Vortex flows exist across a broad range of spatial and temporal scales in the solar atmosphere. Small-scale vortices are thought to play an important role in energy transport in the solar atmosphere. However, their physical properties remain poorly understood due to the limited spatial resolution of the observations. Aims. We explore and analyze the physical properties of small-scale vortices inside magnetic flux tubes using numerical simulations, and investigate whether they contribute to heating the chromosphere in a plage region. Methods. Using the three-dimensional radiative magnetohydrodynamic simulation code MURaM, we perform numerical simulations of a unipolar solar plage region. To detect and isolate vortices we use the swirling strength criterion and select the locations where the fluid is rotating with an angular velocity greater than a certain threshold. We concentrate on small-scale vortices as they are the strongest and carry most of the energy. We explore the spatial profiles of physical quantities such as density and horizontal velocity inside these vortices. Moreover, to learn their general characteristics, a statistical investigation is performed. Results. Magnetic flux tubes have a complex filamentary substructure harboring an abundance of small-scale vortices. At the interfaces between vortices strong current sheets are formed that may dissipate and heat the solar chromosphere. Statistically, vortices have higher densities and higher temperatures than the average values at the same geometrical height in the chromosphere. Conclusions. We conclude that small-scale vortices are ubiquitous in solar plage regions; they are denser and hotter structures that contribute to chromospheric heating, possibly by dissipation of the current sheets formed at their interfaces.

scholarly journals Seismic barriers: theory and numerical simulations

2019 ◽  
Vol 97 ◽  
pp. 03005 ◽  
Author(s):  
Vladimir Bratov ◽  
Alla Ilyashenko ◽  
Nikita Morozov ◽  
Tursunbai Rashidov
Keyword(s):  
Physical Properties ◽  
Numerical Simulations ◽  
Wave Energy ◽  
Seismic Waves ◽  
Fem Simulation ◽  
Specific Region ◽  
Bulk Waves ◽  
Vertical Barriers

The basic idea of a seismic barrier is to protect an area occupied by a building or a group of buildings from seismic waves. Depending on the nature of seismic waves that are the most probable in a specific region, different kinds of seismic barriers are suggested. For example, vertical barriers resembling a wall in a soil can protect from Rayleigh and bulk waves. The FEM simulation reveals that to be effective, such a barrier should be (i) composed of layers with contrast physical properties allowing “trapping” of the wave energy inside some of the layers, and (ii) depth of the barrier should be comparable or greater than the considered seismic wavelength.

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