Multi-Phase Models in Civil Engineering

2014 ◽  
pp. 113-149
Author(s):  
P. Gamnitzer ◽  
M. Aschaber ◽  
G. Hofstetter
Keyword(s):  
Civil Engineering ◽  
Phase Models ◽  
Multi Phase

Tracking the Rheological Behavior Change of a Fresh Granular-Cement Paste Material to a Granular Material Based on DEM

2012 ◽  
Vol 446-449 ◽  
pp. 3803-3809
Author(s):  
Hooman Hoornahad ◽  
Eduard A. B. Koenders
Keyword(s):  
Numerical Simulation ◽  
Rheological Behavior ◽  
Volume Fraction ◽  
Analytical Techniques ◽  
Fluid Models ◽  
Continuum Approach ◽  
Two Phase ◽  
The Common ◽  
Phase Models ◽  
Multi Phase

The common approach to describe the rheological behavior of a granular-paste material relies on a description of the motion within the frame of continuum mechanics. However, since a granular-paste system cannot be considered as a homogeneous continuous fluid its behavior should not be estimated by common fluid models, such as Bingham or Herschell Bulkley models. Therefore, a continuum approach is not considered the best option to study the phase effects of a multi-phase material and its corresponding rheological behavior. In this particular case analytical techniques based on the multi-phase models are required. A more appropriate approach is to consider a granular-paste material as a two phase model that accounts for the effect of the gradually decreasing the volume fraction of the pasty phase until getting to zero value on the rheological behavior of the material. In this investigation, a cone test is used to evaluate the rheological behavior of a granular mix where a discrete element method (DEM) is considered as a basis of the numerical simulation.

scholarly journals Prediction of chloride diffusion coefficients using multi-phase models

2017 ◽  
Vol 69 (3) ◽  
pp. 134-144 ◽  
Author(s):  
Qing-feng Liu ◽  
Dave Easterbrook ◽  
Long-yuan Li ◽  
Dawang Li
Keyword(s):  
Diffusion Coefficients ◽  
Chloride Diffusion ◽  
Phase Models ◽  
Multi Phase

Stability of a Thermodynamically Coherent Multiphase Model

2003 ◽  
Vol 13 (10) ◽  
pp. 1463-1487
Author(s):  
B. Després ◽  
F. Lagoutière ◽  
D. Ramos
Keyword(s):  
Conservation Laws ◽  
Numerical Scheme ◽  
Fluid Model ◽  
Multiphase Model ◽  
Physical Domain ◽  
Rarefaction Waves ◽  
Phase Models ◽  
The Stability ◽  
Multi Phase ◽  
Dimension One

We analyze a hyperbolic system of conservation laws in dimension one, which is a drastic simplification of a multi-phase or multi-velocity fluid model. The physical domain of hyperbolicity is bounded, which is a characteristic of multi-phase models. Our main result is the stability of the domain of hyperbolicity. Due to the degeneracy of the model on the boundary of the hyperbolicity domain, rarefaction waves are not unique. We also propose a numerical scheme for approximate resolution of the model and prove the stability of this scheme.

scholarly journals Modelling carbon-chain species formation in lukewarm corinos with new multi-phase models

2019 ◽  
Vol 622 ◽  
pp. A185 ◽  
Author(s):  
Yao Wang ◽  
Qiang Chang ◽  
Hongchi Wang
Keyword(s):  
Finite Size ◽  
Carbon Chain ◽  
Phase Model ◽  
Finite Size Effect ◽  
Volatile Species ◽  
Two Phase ◽  
Chemical Models ◽  
Species Abundances ◽  
Phase Models ◽  
Multi Phase

Context. Abundant carbon-chain species have been observed towards lukewarm corinos L1527, B228, and L483. These carbon-chain species are believed to be synthesized in the gas phase after CH4 desorbs from the dust grain surface at the temperature around 30 K. Aims. We investigate carbon-chain species formation in lukewarm corinos using a more rigorous numerical method and advanced surface chemical models. We also pay attention to the significance of the finite size effect. Methods. We used the macroscopic Monte Carlo method in our simulations. In addition to the two-phase model, the basic multi-phase model and the new multi-phase models were used for modelling surface chemistry on dust grains. All volatile species can sublime at their sublimation temperatures in the two-phase model while most volatile species are frozen in the ice mantle before water ice sublimes in the basic and the new multi-phase models. The new multi-phase models allow more volatile species to sublime at their sublimation temperatures than the basic multi-phase model does. Results. The significance of the finite size effect is dependent on the duration of the cold phase. The discrepancies between the rate equation approach and the Monte Carlo method decrease as the duration of the cold phase increases. When T ~ 30 K, the abundances of gaseous CH4 and CO in the two-phase model are the highest while the basic multi-phase model predicts the lowest CO and CH4 abundances among all models. The abundances of carbon-chain species in the basic and the new multi-phase models are lower than that in the two-phase model when T ~ 30 K because CH4 is crucial for the synthesis of carbon-chain species. However, because the abundance of electrons increases as the abundance of H3O+ decreases, some carbon-chain species abundances predicted by the basic multi-phase model may not be lower than that in the new multi-phase models. The two-phase model performs best in predicting carbon-chain species abundances to fit observations while the basic multi-phase model works the worst. The abundances of carbon-chain species predicted by the new multi-phase models agree reasonably well with observations. Conclusions. The amount of CH4 can diffuse inside the ice mantle, thus sublime upon warm-up plays a crucial role in the synthesis of carbon-chain species in the gas phase. The carbon-chain species observed in lukewarm corinos may be able to gauge surface chemical models.

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