Water–mineral interaction in hygromechanics of clays exposed to environmental loads: a mixture-theory approach

1992 ◽  
Vol 29 (6) ◽  
pp. 1071-1086 ◽  
Author(s):  
Tomasz A. Hueckel
Keyword(s):  
Mass Transfer ◽  
Mixture Theory ◽  
Adsorbed Water ◽  
Theory Approach ◽  
Environmental Loads ◽  
Fluid Fraction ◽  
Effects Of Temperature ◽  
Dynamics Simulations ◽  
Experimental Findings ◽  
Mineral Interaction

Water–mineral interaction in narrow interstices (<30 Å (1 Å = 0.1 nm)) in dense, saturated clays is discussed in view of recent experimental findings and molecular dynamics simulations. Consequences to the macroscopic behavior are considered. A mixture theory for two interacting constituents is developed. Effects of temperature and chemicals are discussed. A postulate of mass transfer of adsorbed water from solid to fluid fraction caused by thermal or chemical load is then discussed. Theory of plasticity of clays affected by heat or chemicals is developed to deal with the effects of thermal and chemical consolidation. Key words : hydraulic conductivity, effective stress, environmental loads, thermo-chemo-plasticity.

scholarly journals Numerical Study and Experimental Validation of Deformation of FCC CuAl Single Crystal Obtained by Additive Manufacturing

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 582
Author(s):  
Anton Y. Nikonov ◽  
Andrey I. Dmitriev ◽  
Dmitry V. Lychagin ◽  
Lilia L. Lychagina ◽  
Artem A. Bibko ◽  
...  
Keyword(s):  
Single Crystal ◽  
Numerical Study ◽  
Strain Curve ◽  
Aluminum Bronze ◽  
Partial Dislocations ◽  
Slip Planes ◽  
Loaded Material ◽  
Dislocation Movement ◽  
Dynamics Simulations ◽  
Experimental Findings

The importance of taking into account directional solidification of grains formed during 3D printing is determined by a substantial influence of their crystallographic orientation on the mechanical properties of a loaded material. This issue is studied in the present study using molecular dynamics simulations. The compression of an FCC single crystal of aluminum bronze was performed along the <111> axis. A Ni single crystal, which is characterized by higher stacking fault energy (SFE) than aluminum bronze, was also considered. It was found that the first dislocations started to move earlier in the material with lower SFE, in which the slip of two Shockley partials was observed. In the case of the material with higher SFE, the slip of a full dislocation occurred via successive splitting of its segments into partial dislocations. Regardless of the SFE value, the deformation was primarily occurred by means of the formation of dislocation complexes involved stair-rod dislocations and partial dislocations on adjacent slip planes. Hardening and softening segments of the calculated stress–strain curve were shown to correspond to the periods of hindering of dislocations at dislocation pileups and dislocation movement between them. The simulation results well agree with the experimental findings.

Effects of temperature, concentration, and isomer on the hydration structure in monosaccharide solutions

2017 ◽  
Vol 19 (23) ◽  
pp. 15239-15246 ◽  
Author(s):  
Katsufumi Tomobe ◽  
Eiji Yamamoto ◽  
Masato Yasui ◽  
Kenji Yasuoka
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Hydration Structure ◽  
Effects Of Temperature ◽  
Dynamics Simulations

In this study, we elucidated the effects of temperature, concentration, and isomer on the hydration structure in monosaccharide solutions using molecular dynamics simulations.

scholarly journals Efficient Nanoporous Silicon Membranes for Integrated Microfluidic Separation and Sensing Systems

2009 ◽  
Vol 1191 ◽  
Author(s):  
Nazar Ileri ◽  
Sonia E. Létant ◽  
Jerald Britten ◽  
Hoang Nguyen ◽  
Cindy Larson ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Processing System ◽  
Molecular Transport ◽  
Superior Performance ◽  
Electron Conduction ◽  
Microfluidic Separation ◽  
Planar Arrays ◽  
Molecular Separation ◽  
Silicon Membranes ◽  
Dynamics Simulations

AbstractNanoporous devices constitute emerging platforms for selective molecule separation and sensing, with great potential for high throughput and economy in manufacturing and operation. Acting as mass transfer diodes similar to a solid-state device based on electron conduction, conical pores are shown to have superior performance characteristics compared to traditional cylindrical pores. Such phenomena, however, remain to be exploited for molecular separation. Here we present performance results from silicon membranes created by a new synthesis technique based on interferometric lithography. This method creates millimeter sized planar arrays of uniformly tapered nanopores in silicon with pore diameter 100 nm or smaller, ideally-suited for integration into a multi-scale microfluidic processing system. Molecular transport properties of these devices are compared against state-of-the-art polycarbonate track etched (PCTE) membranes. Mass transfer rates of up to fifteen-fold greater than commercial sieve technology are obtained. Complementary results from molecular dynamics simulations on molecular transport are reported.

scholarly journals Influence of Large Relative Tip Clearances for a Micro Radial Fan and Design Guidelines for Increased Efficiency

2020 ◽  
Author(s):  
Patrick H. Wagner ◽  
Jan Van herle ◽  
Lili Gu ◽  
Jürg Schiffmann
Keyword(s):  
Pressure Rise ◽  
Leading Edge ◽  
High Sensitivity ◽  
Design Guidelines ◽  
Tip Clearance ◽  
Small Scale ◽  
Blade Tip ◽  
Dynamics Simulations ◽  
Experimental Findings ◽  
Blade Tip Clearance

Abstract The blade tip clearance loss was studied experimentally and numerically for a micro radial fan with a tip diameter of 19.2mm. Its relative blade tip clearance, i.e., the clearance divided by the blade height of 1.82 mm, was adjusted with different shims. The fan characteristics were experimentally determined for an operation at the nominal rotational speed of 168 krpm with hot air (200 °C). The total-to-total pressure rise and efficiency increased from 49 mbar to 68 mbar and from 53% to 64%, respectively, by reducing the relative tip clearance from 7.7% to the design value of 2.2%. Single and full passage computational fluid dynamics simulations correlate well with these experimental findings. The widely-used Pfleiderer loss correlation with an empirical coefficient of 2.8 fits the numerical simulation and the experiments within +2 efficiency points. The high sensitivity to the tip clearance loss is a result of the design specific speed of 0.80, the highly-backward curved blades (17°), and possibly the low Reynolds number (1 × 105). The authors suggest three main measures to mitigate the blade tip clearance losses for small-scale fans: (1) utilization of high-precision surfaced-grooved gas-bearings to lower the blade tip clearance, (2) a mid-loaded blade design, and (3) an unloaded fan leading edge to reduce the blade tip clearance vortex in the fan passage.

Dynamic model of dehydration melting motivated by a natural analogue: applications to the Ivrea–Verbano zone, northern Italy

1996 ◽  
Vol 87 (1-2) ◽  
pp. 23-31 ◽  
Author(s):  
Scott A. Barboza ◽  
George W. Bergantz
Keyword(s):  
Numerical Model ◽  
Mixture Theory ◽  
Mafic Magma ◽  
Northern Italy ◽  
Porous Media Flow ◽  
Theory Approach ◽  
Dehydration Melting ◽  
Porous Flow ◽  
Crustal Rocks ◽  
Switching Functions

ABSTRACT:Dehydration melting of crustal rocks may commonly occur in response to the intrusion of mafic magma in the mid- or lower crust. However, the relative importance of melt buoyancy, shear or dyking in melt generation and extraction under geologically relevant conditions is not well understood. A numerical model of the partial melting of a metapelite is presented and the model results are compared with the Ivrea-Verbano Zone in northern Italy. The numerical model uses the mixture theory approach to modelling simultaneous convection and phase change and includes special ramping and switching functions to accommodate the rheology of crystal-melt mixtures in accordance with the results of deformation experiments. The model explicitly includes both porous media flow and thermally and compositionally driven bulk convection of a restitecharged melt mass. A range of melt viscosity and critical melt fraction models is considered. General agreement was found between predicted positions of isopleths and those from the Ivrea-Verbano Zone. Maximum melt velocities in the region of porous flow are found to be 1 × 10−7 and 1 × 10−1m per year in the region of viscous flow. The results indicate that melt buoyancy alone may not be a sufficient agent for melt extraction and that extensive, vigorous convection of partially molten rocks above mafic bodies is unlikely, in accord with direct geological examples.

EFFECT OF STENOSIS SEVERITY ON SHEAR-INDUCED DIFFUSION OF RED BLOOD CELLS IN CORONARY ARTERIES

2019 ◽  
Vol 19 (05) ◽  
pp. 1950034 ◽  
Author(s):  
ABDULRAJAK BURADI ◽  
SUMANT MORAB ◽  
ARUN MAHALINGAM
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Mixture Theory ◽  
Theory Approach ◽  
Newtonian Viscosity ◽  
Maximum Fluctuation ◽  
Stenosis Severity ◽  
Flux Model ◽  
First Time ◽  
Arterial Endothelial Cells

In large blood vessels, migration of red blood cells (RBCs) affects the concentration of platelets and the transport of oxygen to the arterial endothelial cells. In this work, we investigate the locations where hydrodynamic diffusion of RBCs occurs and the effects of stenosis severity on shear-induced diffusion (SID) of RBCs, concentration distribution and wall shear stress (WSS). For the first time, multiphase mixture theory approach with Phillips shear-induced diffusive flux model coupled with Quemada non-Newtonian viscosity model has been applied to numerically simulate the RBCs macroscopic behavior in four different degrees of stenosis (DOS) geometries, viz., 30%, 50%, 70% and 85%. Considering SID of RBCs, the calculated average WSS increased by 77.70% which emphasises the importance of SID in predicting hemodynamic parameters. At the stenosis throat, it was observed that 85% DOS model had the lowest concentration of RBCs near the wall and highest concentration at the center. For the stenosis models with 70% and 85% DOS, the RBC lumen wall concentration at the distal section of stenosis becomes inhomogeneous with the maximum fluctuation of 1.568%. Finally, the wall regions with low WSS and low RBC concentrations correlate well with the atherosclerosis sites observed clinically.

scholarly journals Effects of temperature and pore structure on the release of methane in zeolite nanochannels

RSC Advances ◽  
2019 ◽  
Vol 9 (17) ◽  
pp. 9546-9554 ◽  
Author(s):  
Xu Cheng ◽  
Zhigang Li ◽  
Ya-Ling He
Keyword(s):  
Molecular Dynamics ◽  
Pore Structure ◽  
Molecular Dynamics Simulations ◽  
Pore Size ◽  
Effects Of Temperature ◽  
Dynamics Simulations

The effects of temperature and pore size on release of methane in zeolite nanochannels is investigated by molecular dynamics simulations.

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