scholarly journals Discrete vs. continuum-scale simulation of radiative transfer in semitransparent two-phase media

2011 ◽  
Vol 112 (9) ◽  
pp. 1450-1459 ◽  
Author(s):  
Jörg Petrasch ◽  
Sophia Haussener ◽  
Wojciech Lipiński
Keyword(s):  
Radiative Transfer ◽  
Two Phase ◽  
Continuum Scale

Inverse modeling of transient three-dimensional core-scale two-phase flows

2021 ◽  
Author(s):  
Andrea Manzoni ◽  
Aronne Dell'Oca ◽  
Martina Siena ◽  
Alberto Guadagnini
Keyword(s):  
Capillary Pressure ◽  
Random Noise ◽  
Three Dimensional ◽  
Population Based ◽  
Model Parameters ◽  
Reference Scenario ◽  
Two Phase ◽  
De Algorithm ◽  
Continuum Scale ◽  
Available Information

<p>We consider transient three-dimensional (3D) two-phase (oil and water) flows, taking place at the core-scale. In this context, we aim at exploiting the full information content associated with available information of (i) the 3D distribution of oil saturation and (ii) the overall pressure difference across the rock sample, to estimate the set of model parameters. We consider a continuum-scale description of the system behavior upon relying on the widely employed Brooks-Corey model for the characterization of relative permeabilities and on the capillary pressure correlation introduced by Skjaeveland et al. (2000). To provide a transparent way of assessing the results of the inversion, we rely on a synthetic reference scenario. The latter is intended to mimic having at our disposal 3D and section-averaged distributions of (time-dependent) oil saturations of the kind that can be acquired during typical laboratory experiments. These are in turn corrupted by way of a random noise, to address the influence of experimental uncertainties. We focus on diverse scenarios encompassing imbibition and drainage conditions. We employ two population-based optimization algorithms, i.e., (i) the particle swarm optimization (PSO); and (ii) the differential evolution (DE), which enable one to effectively tackle the high-dimensionality parameters space (i.e., 12 dimensions in our setting) we consider. Model calibration results are of satisfactory quality for the majority of the tested scenarios, whereas the DE algorithm is associated with highest effectiveness.</p><p><strong>References</strong></p><p>S.M. Skjaeveland; L.M. Siqveland; A. Kjosavik; W.L. Hammervold Thomas; G.A. Virnovsky (2000). Capillary Pressure Correlation for Mixed-Wet Reservoirs SPE Res Eval & Eng 3 (01): 60–67. https://doi.org/10.2118/60900-PA</p>

Consequences of viscous anisotropy in a deforming, two-phase aggregate. Part 1. Governing equations and linearized analysis

2013 ◽  
Vol 734 ◽  
pp. 424-455 ◽  
Author(s):  
Yasuko Takei ◽  
Richard F. Katz
Keyword(s):  
Shear Stress ◽  
Numerical Solutions ◽  
Shear Plane ◽  
High Porosity ◽  
Governing Equations ◽  
Two Phase ◽  
The Matrix ◽  
Continuum Scale ◽  
Torsional Flow ◽  
Matrix Shear

AbstractIn partially molten regions of Earth, rock and magma coexist as a two-phase aggregate in which the solid grains of rock form a viscously deformable framework or matrix. Liquid magma resides within the permeable network of pores between grains. Deviatoric stress causes the distribution of contact area between solid grains to become anisotropic; in turn, this causes anisotropy of the matrix viscosity at the continuum scale. In this two-paper set, we predict the consequences of viscous anisotropy for flow of two-phase aggregates in three configurations: simple shear, Poiseuille, and torsional flow. Part 1 presents the governing equations and an analysis of their linearized form. Part 2 (Katz & Takei, J. Fluid Mech., vol. 734, 2013, pp. 456–485) presents numerical solutions of the full, nonlinear model. In our theory, the anisotropic viscosity tensor couples shear and volumetric components of the matrix stress/strain rate. This coupling, acting over a gradient in shear stress, causes segregation of liquid and solid. Liquid typically migrates toward higher shear stress, but under specific conditions, the opposite can occur. Furthermore, it is known that in a two-phase aggregate with a porosity-weakening viscosity, matrix shear causes porosity perturbations to grow into a banded or sheeted structure. We show that viscous anisotropy reduces the angle between these emergent high-porosity features and the shear plane. Laboratory experiments produce similar, high-porosity features. We hypothesize that the low angle of porosity bands in such experiments is the result of viscous anisotropy. We therefore predict that experiments incorporating a gradient in shear stress will develop sample-wide liquid–solid segregation due to viscous anisotropy.

scholarly journals 3D radiative transfer modelling of the dusty tori around active galactic nuclei as a clumpy two-phase medium

2012 ◽  
Vol 420 (4) ◽  
pp. 2756-2772 ◽  
Author(s):  
Marko Stalevski ◽  
Jacopo Fritz ◽  
Maarten Baes ◽  
Theodoros Nakos ◽  
Luka Č. Popović
Keyword(s):  
Radiative Transfer ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Two Phase ◽  
Phase Medium ◽  
Transfer Modelling

scholarly journals Understanding dislocation mechanics at the mesoscale using phase field dislocation dynamics

2016 ◽  
Vol 374 (2066) ◽  
pp. 20150166 ◽  
Author(s):  
I. J. Beyerlein ◽  
A. Hunter
Keyword(s):  
Phase Field ◽  
Dislocation Dynamics ◽  
Atomic Scale ◽  
Two Phase ◽  
Cubic Metals ◽  
Cubic Materials ◽  
Dislocation Mechanics ◽  
Recent Developments ◽  
Continuum Scale ◽  
Field Dislocation

In this paper, we discuss the formulation, recent developments and findings obtained from a mesoscale mechanics technique called phase field dislocation dynamics (PFDD). We begin by presenting recent advancements made in modelling face-centred cubic materials, such as integration with atomic-scale simulations to account for partial dislocations. We discuss calculations that help in understanding grain size effects on transitions from full to partial dislocation-mediated slip behaviour and deformation twinning. Finally, we present recent extensions of the PFDD framework to alternative crystal structures, such as body-centred cubic metals, and two-phase materials, including free surfaces, voids and bi-metallic crystals. With several examples we demonstrate that the PFDD model is a powerful and versatile method that can bridge the length and time scales between atomistic and continuum-scale methods, providing a much needed understanding of deformation mechanisms in the mesoscale regime.

scholarly journals The Effect of Pore-Scale Two-Phase Flow on Mineral Reaction Rates

2022 ◽  
Vol 3 ◽  
Author(s):  
Pei Li ◽  
Hang Deng ◽  
Sergi Molins
Keyword(s):  
Multiphase Flow ◽  
Aqueous Phase ◽  
Two Phase Flow ◽  
Reaction Rates ◽  
Phase Flow ◽  
Pore Scale ◽  
Two Phase ◽  
Calcite Dissolution ◽  
Mineral Reaction ◽  
Continuum Scale

In various natural and engineered systems, mineral–fluid interactions take place in the presence of multiple fluid phases. While there is evidence that the interplay between multiphase flow processes and reactions controls the evolution of these systems, investigation of the dynamics that shape this interplay at the pore scale has received little attention. Specifically, continuum scale models rarely consider the effect of multiphase flow parameters on mineral reaction rates or apply simple corrections as a function of the reactive surface area or saturation of the aqueous phase, without developing a mechanistic understanding of the pore-scale dynamics. In this study, we developed a framework that couples the two-phase flow simulator of OpenFOAM (open field operation and manipulation) with the geochemical reaction capability of CrunchTope to examine pore-scale dynamics of two phase flow and their impacts on mineral reaction rates. For our investigations, flat 2D channels and single sine wave channels were used to represent smooth and rough geometries. Calcite dissolution in these channels was quantified with single phase flow and two phase flow at a range of velocities. We observed that the bulk calcite dissolution rates were not only affected by the loss of reactive surface area as it becomes occupied by the non-reactive non-aqueous phase, but also largely influenced by the changes in local velocity profiles, e.g., recirculation zones, due to the presence of the non-aqueous phase. The extent of the changes in reaction rates in the two-phase systems compared to the corresponding single phase system is dependent on the flow rate (i.e., capillary number) and channel geometry, and follows a non-monotonic relationship with respect to aqueous saturation. The pore-scale simulation results highlight the importance of interfacial dynamics in controlling mineral reactions and can be used to better constrain reaction rate descriptions in multiphase continuum scale models. These results also emphasize the need for experimental studies that underpin the development of mechanistic models for multiphase flow in reactive systems.

scholarly journals Experimental study of radiative transfer in semi-transparent composite materials at different temperatures

2021 ◽  
Vol 2116 (1) ◽  
pp. 012062
Author(s):  
F Retailleau ◽  
V Allheily ◽  
L Merlat ◽  
J-F Henry ◽  
J Randrianalisoa
Keyword(s):  
Radiative Transfer ◽  
Glass Fibers ◽  
Homogeneous Medium ◽  
Radiative Properties ◽  
Resin Matrix ◽  
Two Phase ◽  
Heated Sample ◽  
Phase Medium ◽  
Different Temperatures ◽  
Transparent Composite

Abstract This study deals with the analysis of the propagation of radiation within a diffusing semi-transparent composite medium with rough boundaries. The two-phase medium (resin matrix and glass fibers reinforcement) is treated as an equivalent homogeneous medium characterized by volumetric radiative properties (extinction coefficient, albedo and phase function) and boundary scattering properties. The aim is to identify the radiative properties at different temperatures ranging from room temperature to 200°C. The identification method (Gauss-Newton) uses bidirectional reflectance and transmittance values. The experimental results are obtained using a spectrophotometer equipped with a goniometer and a heated sample holder. The Monte Carlo method is used to solve the Radiative Transfer Equation (RTE) in order to obtain the theoretical values.

Consequences of viscous anisotropy in a deforming, two-phase aggregate. Part 2. Numerical solutions of the full equations

2013 ◽  
Vol 734 ◽  
pp. 456-485 ◽  
Author(s):  
Richard F. Katz ◽  
Yasuko Takei
Keyword(s):  
Simple Shear ◽  
Poiseuille Flow ◽  
Numerical Solutions ◽  
High Porosity ◽  
Two Phase ◽  
Band Formation ◽  
Porosity Evolution ◽  
The Matrix ◽  
Continuum Scale ◽  
Torsional Flow

AbstractIn partially molten regions of Earth, rock and magma coexist as a two-phase aggregate in which the solid grains of rock form a viscously deformable framework or matrix. Liquid magma resides within the permeable network of pores between grains. Deviatoric stress causes the distribution of contact area between solid grains to become anisotropic; this, in turn, causes anisotropy of the matrix viscosity at the continuum scale. In the second of a two-paper set, we use numerical methods to solve the full, nonlinear, time-dependent equations governing this system. We consider porosity evolution in simple shear, Poiseuille and torsional flow. Under viscous anisotropy, there are two modes of porosity evolution: base-state segregation, which modifies the domain-scale porosity distribution, and growth of porosity perturbations into melt-rich bands. Simulation results with fixed anisotropy confirm and extend the linearized analysis of Part 1 (Takei & Katz, J. Fluid Mech., vol. 734, 2013, pp. 424–455). Most importantly, numerical solutions capture the interaction of the two modes: under Poiseuille flow, base-state segregation enhances band formation; under torsional flow, bands are suppressed. Simulations also show that low band angle is maintained by nonlinear processes such as reconnection of high-porosity segments and by back-rotation of the compacted regions between bands. Simulations with dynamic anisotropy modify these results, further lowering the average band angle. The effective viscosity of each flow is controlled by base-state segregation; it does not evolve under simple shear, decreases in Poiseuille flow and increases in torsion. We propose a reinterpretation of experimental results in terms of the consequences of viscous anisotropy.

Radiative Transfer in Two-Phase Dispersed Materials

2010 ◽  
pp. 187-234
Author(s):  
Jaona Randrianalisoa ◽  
Rémi Coquard ◽  
Dominique Baillis
Keyword(s):  
Radiative Transfer ◽  
Two Phase
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