scholarly journals Upscaling Fractured Heterogeneous Media: Permeability and Mass Exchange Coefficient

2005 ◽  
Vol 73 (1) ◽  
pp. 41-46 ◽  
Author(s):  
Moussa Kfoury ◽  
Rachid Ababou ◽  
Benoît Noetinger ◽  
Michel Quintard
Keyword(s):  
Large Scale ◽  
Fluid Transport ◽  
Heterogeneous Media ◽  
Porous Matrix ◽  
Exchange Coefficient ◽  
Flow Equations ◽  
Unit Scale ◽  
Homogenization Methods ◽  
Fracture Distribution ◽  
Equivalent Properties

In order to optimize oil recuperation, to secure waste storage, CO2 sequestration and describe more precisely many environmental problems in the underground, we need to improve some homogenization methods that calculate petrophysical parameters. In this paper, we discuss the upscaling of fluid transport equations in fractured heterogeneous media consisting of the fractures themselves and a heterogeneous porous matrix. Our goal is to estimate precisely the fluid flow parameters like permeability and fracture/matrix exchange coefficient at large scale. Two approaches are possible. The first approach consists in calculating the large-scale equivalent properties in one upscaling step, starting with a single continuum flow model at the local scale. The second approach is to perform upscaling in two sequential steps: first, calculate the equivalent properties at an intermediate scale called the ”unit scale,” and, second, average the flow equations up to the large scale. We have implemented the two approaches and applied them to randomly distributed fractured systems. The results allowed us to obtain valuable information in terms of sizes of representative elementary volume associated to a given fracture distribution.

Characterization of fluid transport properties of reservoirs using induced microseismicity

Geophysics ◽  
2002 ◽  
Vol 67 (1) ◽  
pp. 212-220 ◽  
Author(s):  
Serge A. Shapiro ◽  
Elmar Rothert ◽  
Volker Rath ◽  
Jan Rindschwentner
Keyword(s):  
Large Scale ◽  
Eikonal Equation ◽  
Fluid Transport ◽  
Heterogeneous Media ◽  
Reservoir Characterization ◽  
Homogeneous Medium ◽  
Front Propagation ◽  
Characteristic Size ◽  
Permeability Tensor ◽  
Heterogeneous Rock

We systematically describe an approach to estimate the large‐scale permeability of reservoirs using seismic emission (microseismicity) induced by fluid injection. We call this approach seismicity‐based reservoir characterization (SBRC). A simple variant of the approach is based on the hypothesis that the triggering front of hydraulically‐induced microseismicity propagates like a diffusive process (pore pressure relaxation) in an effective homogeneous anisotropic poroelastic fluid‐saturated medium. The permeability tensor of this effective medium is the permeability tensor upscaled to the characteristic size of the seismically active heterogeneous rock volume. We show that in a homogeneous medium the surface of the seismicity triggering front has the same form as the group‐velocity surface of thelow‐frequency anisotropic, second‐type Biots wave describing kinematic aspects of triggering‐front propagation in a way similar to the eikonal equation for seismic wavefronts. In the case of isotropic heterogeneous media, the inversion for the hydraulic properties of rocks follows from a direct application of this equation. In the case of an anisotropic heterogeneous medium, only the magnitude of a global effective permeability tensor can be mapped in a 3‐D spatial domain. We demonstrate the method on several field examples and also test the eikonal equation‐based inversion.

scholarly journals Heat Transfer in Rotating Serpentine Passages With Trips Normal to the Flow

1992 ◽  
Vol 114 (4) ◽  
pp. 847-857 ◽  
Author(s):  
J. H. Wagner ◽  
B. V. Johnson ◽  
R. A. Graziani ◽  
F. C. Yeh
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Large Scale ◽  
Flow Direction ◽  
Operating Conditions ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Flow Equations ◽  
Turbine Blade Cooling ◽  
Heat Transfer Coefficients

Experiments were conducted to determine the effects of buoyancy and Coriolis forces on heat transfer in turbine blade internal coolant passages. The experiments were conducted with a large-scale, multipass, heat transfer model with both radially inward and outward flow. Trip strips on the leading and trailing surfaces of the radial coolant passages were used to produce the rough walls. An analysis of the governing flow equations showed that four parameters influence the heat transfer in rotating passages: coolant-to-wall temperature ratio, Rossby number, Reynolds number, and radius-to-passage hydraulic diameter ratio. The first three of these four parameters were varied over ranges that are typical of advanced gas turbine engine operating conditions. Results were correlated and compared to previous results from stationary and rotating similar models with trip strips. The heat transfer coefficients on surfaces, where the heat transfer increased with rotation and buoyancy, varied by as much as a factor of four. Maximum values of the heat transfer coefficients with high rotation were only slightly above the highest levels obtained with the smooth wall model. The heat transfer coefficients on surfaces where the heat transfer decreased with rotation, varied by as much as a factor of three due to rotation and buoyancy. It was concluded that both Coriolis and buoyancy effects must be considered in turbine blade cooling designs with trip strips and that the effects of rotation were markedly different depending upon the flow direction.

Large-scale analysis of focused ultrasound in heterogeneous media

2010 ◽  
Author(s):  
Junko Uebayashi ◽  
Yoshiaki Tamura ◽  
Yoichiro Matsumoto ◽  
Kullervo Hynynen ◽  
Jacques Souquet
Keyword(s):  
Large Scale ◽  
Focused Ultrasound ◽  
Heterogeneous Media ◽  
Scale Analysis ◽  
Large Scale Analysis

scholarly journals A Multiple-Grid Lattice Boltzmann Method for Natural Convection under Low and High Prandtl Numbers

Fluids ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 148
Author(s):  
Seyed Amin Nabavizadeh ◽  
Himel Barua ◽  
Mohsen Eshraghi ◽  
Sergio D. Felicelli
Keyword(s):  
Natural Convection ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Large Scale ◽  
Bgk Model ◽  
Flow Equations ◽  
Wide Range ◽  
Prandtl Numbers ◽  
Boltzmann Method ◽  
Benchmark Solutions

A multi-distribution lattice Boltzmann Bhatnagar–Gross–Krook (BGK) model with a multiple-grid lattice Boltzmann (MGLB) model is proposed to efficiently simulate natural convection over a wide range of Prandtl numbers. In this method, different grid sizes and time steps for heat transfer and fluid flow equations are chosen. The model is validated against natural convection in a square cavity, since extensive benchmark solutions are available for that problem. The proposed method can resolve the computational difficulty in simulating problems with very different time scales, in particular, when using extremely low or high Prandtl numbers. The technique can also enhance computational speed and stability while keeping the simplicity of the BGK method. Compared with the conventional lattice Boltzmann method, the simulation time can be reduced up to one-tenth of the time while maintaining the accuracy in an acceptable range. The proposed model can be extended to other lattice Boltzmann collision models and three-dimensional cases, making it a great candidate for large-scale simulations.

Large-scale Structure and Turbulence Transport in the Young Solar Wind – Comparison of Parker Solar Probe Observations with a Global 3D Reynolds-averaged MHD Model

2021 ◽  
Author(s):  
Rohit Chhiber ◽  
Arcadi Usmanov ◽  
William Matthaeus ◽  
Melvyn Goldstein ◽  
Riddhi Bandyopadhyay
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Transport Equations ◽  
Turbulence Energy ◽  
Reynolds Stresses ◽  
Mean Flow ◽  
Coulomb Collisions ◽  
Flow Equations ◽  
Simulation Results ◽  
Turbulence Transport

<div>Simulation results from a global <span>magnetohydrodynamic</span> model of the solar corona and the solar wind are compared with Parker Solar <span>Probe's</span> (<span>PSP</span>) observations during its first several orbits. The fully three-dimensional model (<span>Usmanov</span> <span>et</span> <span>al</span>., 2018, <span>ApJ</span>, 865, 25) is based on Reynolds-averaged mean-flow equations coupled with turbulence transport equations. The model accounts for effects of electron heat conduction, Coulomb collisions, Reynolds stresses, and heating of protons and electrons via nonlinear turbulent cascade. Turbulence transport equations for turbulence energy, cross <span>helicity</span>, and correlation length are solved concurrently with the mean-flow equations. We specify boundary conditions at the coronal base using solar synoptic <span>magnetograms</span> and calculate plasma, magnetic field, and turbulence parameters along the <span>PSP</span> trajectory. We also accumulate data from all orbits considered, to obtain the trends observed as a function of heliocentric distance. Comparison of simulation results with <span>PSP</span> data show general agreement. Finally, we generate synthetic fluctuations constrained by the local rms turbulence amplitude given by the model, and compare properties of this synthetic turbulence with PSP observations.</div>

scholarly journals A Flow Perspective on Nonlinear Least-Squares Problems

2020 ◽  
Vol 48 (4) ◽  
pp. 987-1003
Author(s):  
Hans Georg Bock ◽  
Jürgen Gutekunst ◽  
Andreas Potschka ◽  
María Elena Suaréz Garcés
Keyword(s):  
Least Squares ◽  
Newton Method ◽  
Large Scale ◽  
Gradient Flow ◽  
Nonlinear Least Squares ◽  
Bundle Adjustment ◽  
Least Squares Problems ◽  
Flow Equations ◽  
Backward Euler ◽  
Forward Euler

AbstractJust as the damped Newton method for the numerical solution of nonlinear algebraic problems can be interpreted as a forward Euler timestepping on the Newton flow equations, the damped Gauß–Newton method for nonlinear least squares problems is equivalent to forward Euler timestepping on the corresponding Gauß–Newton flow equations. We highlight the advantages of the Gauß–Newton flow and the Gauß–Newton method from a statistical and a numerical perspective in comparison with the Newton method, steepest descent, and the Levenberg–Marquardt method, which are respectively equivalent to Newton flow forward Euler, gradient flow forward Euler, and gradient flow backward Euler. We finally show an unconditional descent property for a generalized Gauß–Newton flow, which is linked to Krylov–Gauß–Newton methods for large-scale nonlinear least squares problems. We provide numerical results for large-scale problems: An academic generalized Rosenbrock function and a real-world bundle adjustment problem from 3D reconstruction based on 2D images.

Industrial biomanufacturing: The future of chemical production

Science ◽  
2017 ◽  
Vol 355 (6320) ◽  
pp. aag0804 ◽  
Author(s):  
James M. Clomburg ◽  
Anna M. Crumbley ◽  
Ramon Gonzalez
Keyword(s):  
Large Scale ◽  
Current Model ◽  
Small Scale ◽  
Process Conditions ◽  
Test Bed ◽  
Chemical Production ◽  
Distributed Resources ◽  
Chemical Manufacturing ◽  
Unit Scale ◽  
Capital Efficiency

The current model for industrial chemical manufacturing employs large-scale megafacilities that benefit from economies of unit scale. However, this strategy faces environmental, geographical, political, and economic challenges associated with energy and manufacturing demands. We review how exploiting biological processes for manufacturing (i.e., industrial biomanufacturing) addresses these concerns while also supporting and benefiting from economies of unit number. Key to this approach is the inherent small scale and capital efficiency of bioprocesses and the ability of engineered biocatalysts to produce designer products at high carbon and energy efficiency with adjustable output, at high selectivity, and under mild process conditions. The biological conversion of single-carbon compounds represents a test bed to establish this paradigm, enabling rapid, mobile, and widespread deployment, access to remote and distributed resources, and adaptation to new and changing markets.

Metamorphic fluids and transtension in the Cantabrian Mountains of northern Spain: an application of the conodont colour alteration index

1986 ◽  
Vol 123 (6) ◽  
pp. 673-681 ◽  
Author(s):  
J. G. M. Raven ◽  
Ben A. Van Der Pluijm
Keyword(s):  
Large Scale ◽  
Fluid Transport ◽  
Spatial Relationship ◽  
Structural Features ◽  
Lower Permian ◽  
Low Grade ◽  
Northern Spain ◽  
Cantabrian Zone ◽  
Conodont Colour Alteration Index ◽  
Colour Alteration

AbstractConodont colour alteration index (CAI) values from Upper Paleozoic rocks in the Cantabrian zone of northern Spain show that temperatures during Hercynian metamorphism locally exceeded 300 °C. Various temperature domains have been defined, which are generally separated by fundamental structures. These domains do not correspond with the tripartite subdivision based on stratigraphic analysis.The observed CAI values of conodonts are in general agreement with the mineral paragenesis. Areas with high CAI values display extensive alteration and mineralization, and where CAI values exceed 4–4.5 (>200 °C) slaty cleavage has developed.The Cantabrian zone is an area of very low grade metamorphism, where peak conditions were reached in Upper Carboniferous to Lower Permian times. The characteristics of the metamorphism and its spatial relationship with major faults suggest that fluids were the main source for regional heating and that fluid transport was focussed along crustal-scale structural features.The overall deformation regime in this part of the Variscan orogen of western Europe is interpreted to be large-scale transtension. This is in agreement with earlier proposed models for the formation of Upper Palaeozoic basins in this area.

scholarly journals Heat Transfer in Rotating Serpentine Passages With Trips Normal to the Flow

1991 ◽  
Author(s):  
J. H. Wagner ◽  
B. V. Johnson ◽  
R. A. Graziani ◽  
F. C. Yeh
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Large Scale ◽  
Flow Direction ◽  
Operating Conditions ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Flow Equations ◽  
Turbine Blade Cooling ◽  
Heat Transfer Coefficients

Experiments were conducted to determine the effects of buoyancy and Coriolis forces on heat transfer in turbine blade internal coolant passages. The experiments were conducted with a large scale, multi–pass, heat transfer model with both radially inward and outward flow. Trip strips on the leading and trailing surfaces of the radial coolant passages were used to produce the rough walls. An analysis of the governing flow equations showed that four parameters influence the heat transfer in rotating passages: coolant–to–wall temperature ratio, Rossby number, Reynolds number and radius–to–passage hydraulic diameter ratio. The first three of these four parameters were varied over ranges which are typical of advanced gas turbine engine operating conditions. Results were correlated and compared to previous results from stationary and rotating similar models with trip strips. The heat transfer coefficients on surfaces, where the heat transfer increased with rotation and buoyancy, varied by as much as a factor of four. Maximum values of the heat transfer coefficients with high rotation were only slightly above the highest levels obtained with the smooth wall model. The heat transfer coefficients on surfaces, where the heat transfer decreased with rotation, varied by as much as a factor of three due to rotation and buoyancy. It was concluded that both Coriolis and buoyancy effects must be considered in turbine blade cooling designs with trip strips and that the effects of rotation were markedly different depending upon the flow direction.

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