scholarly journals Direct numerical simulation of wave propagation in saturated random granular packings using coupled LBM-DEM

2021 ◽  
Vol 249 ◽  
pp. 14003
Author(s):  
Hongyang Cheng ◽  
Stefan Luding ◽  
Jens Harting ◽  
Vanessa Magnanimo
Keyword(s):  
Granular Media ◽  
Volume Fraction ◽  
Saturated Porous Medium ◽  
Pore Fluid ◽  
Frequency Space ◽  
Wave Velocities ◽  
Shear Wave Velocities ◽  
Confining Pressures ◽  
Granular Packings ◽  
Boltzmann Method

Poroelasticity theory predicts wave velocities in a saturated porous medium through a coupling between the bulk deformation of the solid skeleton and porous fluid flow. The challenge emerges below the characteristic wavelengths at which hydrodynamic interactions between grains and pore fluid become important. We investigate the pressure and volume fraction dependence of compressional- and shear-wave velocities in fluid-saturated, random, isotropic, frictional granular packings. The lattice Boltzmann method (LBM) and discrete element method (DEM) are two-way coupled to capture the particle-pore fluid interactions; an acoustic source is implemented to insert a traveling wave from the fluid reservoir to the saturated medium. We extract wave velocities from the acoustic branches in the wavenumber-frequency space, for a range of confining pressures and volume fractions. For random isotropic granular media the pressure-wave velocity data collapse on a single curve when scaled properly by the volume fraction.

scholarly journals Relationships between Dynamic Elastic Moduli in Shale Reservoirs

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6001
Author(s):  
Sheyore John Omovie ◽  
John P. Castagna
Keyword(s):  
Organic Carbon ◽  
Shear Modulus ◽  
Elastic Moduli ◽  
Volume Fraction ◽  
P Wave ◽  
Wave Velocities ◽  
Shear Wave Velocities ◽  
Average Formation ◽  
Dynamic Elastic Moduli ◽  
Shale Reservoirs

Sonic log compressional and shear-wave velocities combined with logged bulk density can be used to calculate dynamic elastic moduli in organic shale reservoirs. We use linear multivariate regression to investigate modulus prediction when shear-wave velocities are not available in seven unconventional shale reservoirs. Using only P-wave modulus derived from logged compressional-wave velocity and density as a predictor of dynamic shear modulus in a single bivariate regression equation for all seven shale reservoirs results in prediction standard error of less than 1 GPa. By incorporating compositional variables in addition to P-wave modulus in the regression, the prediction standard error is reduced to less than 0.8 GPa with a single equation for all formations. Relationships between formation bulk and shear moduli are less well defined. Regressing against formation composition only, we find the two most important variables in predicting average formation moduli to be fractional volume of organic matter and volume of clay in that order. While average formation bulk modulus is found to be linearly related to volume fraction of total organic carbon, shear modulus is better predicted using the square of the volume fraction of total organic carbon. Both Young’s modulus and Poisson’s ratio decrease with increasing TOC while increasing clay volume decreases Young’s modulus and increases Poisson’s ratio.

Elastic Properties of Low Density Core (LDC) Ti-6Al-4V Sandwich Cores

1998 ◽  
Vol 521 ◽  
Author(s):  
D. T. Queheillalt ◽  
H. N. G. Wadley ◽  
D. S. Schwartz
Keyword(s):  
Elastic Properties ◽  
Volume Fraction ◽  
Analytical Models ◽  
Low Density ◽  
Ultrasonic Methods ◽  
Wave Velocities ◽  
Shear Wave Velocities ◽  
High Temperature Anneal ◽  
Porous Microstructure ◽  
Gas Expansion

ABSTRACTLightweight, structurally efficient low density core (LDC) sandwich structures can be produced by entrapping argon gas within a finely dispersed distribution of pores in a microstructure and using a high temperature anneal to cause pore growth by gas expansion. This results in a porous microstructure with a relative density as low as ∼0.70. Laser ultrasonic methods have been used to measure the longitudinal and shear wave velocities and hence the elastic properties of LDC Ti-6Al-4V cores prior to, and after gas expansion treatments of up to 48 hr at 920°C. The data was compared with several analytical models for predicting the volume fraction of porosity dependent elastic properties of porous materials.

TEMPERATURE DEPENDENCE OF COMPRESSIONAL AND SHEAR WAVE VELOCITIES IN ROCKS

Geophysics ◽  
1977 ◽  
Vol 42 (5) ◽  
pp. 950-956 ◽  
Author(s):  
Aytekin Timur
Keyword(s):  
Temperature Dependence ◽  
Shear Wave ◽  
Compressional Wave ◽  
Pore Fluid ◽  
Wave Velocities ◽  
Shear Wave Velocities

Concurrent measurements of compressional and shear wave velocities were conducted as functions of temperature on two sandstone and seven carbonate samples subjected to simulated overburden and pore fluid pressures. On the average, the compressional wave velocities decreased by 1.7 percent and the shear wave velocities by 0.9 percent for a 100°C increase in temperature.

scholarly journals Waterfall Algorithm as a tool of investigation the geometrical features of granular porous media

2021 ◽  
Author(s):  
Wojciech Sobieski
Keyword(s):  
Particle Size ◽  
Porous Media ◽  
Lattice Boltzmann ◽  
Granular Media ◽  
Density Ratio ◽  
Geometrical Features ◽  
Granular Porous Media ◽  
Collision Density ◽  
Boltzmann Method ◽  
The Impact

AbstractThe paper describes the so-called Waterfall Algorithm, which may be used to calculate a set of parameters characterising the spatial structure of granular porous media, such as shift ratio, collision density ratio, consolidation ratio, path length and minimum tortuosity. The study is performed for 1800 different two-dimensional random pore structures. In each geometry, 100 individual paths are calculated. The impact of porosity and the particle size on the above-mentioned parameters is investigated. It was stated in the paper, that the minimum tortuosity calculated by the Waterfall Algorithm cannot be used directly as a representative tortuosity of pore channels in the Kozeny or the Carman meaning. However, it may be used indirect by making the assumption that a unambiguous relationship between the representative tortuosity and the minimum tortuosity exists. It was also stated, that the new parameters defined in the present study are sensitive on the porosity and the particle size and may be therefore applied as indicators of the geometry structure of granular media. The Waterfall Algorithm is compared with other methods of determining the tortuosity: A-Star Algorithm, Path Searching Algorithm, Random Walk technique, Path Tracking Method and the methodology of calculating the hydraulic tortuosity based on the Lattice Boltzmann Method. A very short calculation time is the main advantage of the Waterfall Algorithm, what meant, that it may be applied in a very large granular porous media.

scholarly journals Experimental Investigation of Wave Velocity-Permeability Model for Granite Subjected to Different Temperature Processing

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Guanghui Jiang ◽  
Jianping Zuo ◽  
Teng Ma ◽  
Xu Wei
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Wave Velocity ◽  
Pore Fluid ◽  
Rock Matrix ◽  
Permeability Model ◽  
Wave Velocities ◽  
Before And After ◽  
Different Temperatures ◽  
Increasing Temperature

Understanding the change of permeability of rocks before and after heating is of great significance for exploitation of hydrocarbon resources and disposal of nuclear waste. The rock permeability under high temperature cannot be measured with most of the existing methods. In this paper, quality, wave velocity, and permeability of granite specimen from Maluanshan tunnel are measured after high temperature processing. Quality and wave velocity of granite decrease and permeability of granite increases with increasing temperature. Using porosity as the medium, a new wave velocity-permeability model is established with modified wave velocity-porosity formula and Kozeny-Carman formula. Under some given wave velocities and corresponding permeabilities through experiment, the permeabilities at different temperatures and wave velocities can be obtained. By comparing the experimental and the theoretical results, the proposed formulas are verified. In addition, a sensitivity analysis is performed to examine the effect of particle size, wave velocities in rock matrix, and pore fluid on permeability: permeability increases with increasing particle size, wave velocities in rock matrix, and pore fluid; the higher the rock wave velocity, the lower the effect of wave velocities in rock matrix and pore fluid on permeability.

Soil moisture assessment by means of compressional and shear wave velocities: Theoretical analysis and experimental setup

Measurement ◽  
2010 ◽  
Vol 43 (3) ◽  
pp. 344-352 ◽  
Author(s):  
F. Adamo ◽  
F. Attivissimo ◽  
L. Fabbiano ◽  
N. Giaquinto ◽  
M. Spadavecchia
Keyword(s):  
Soil Moisture ◽  
Theoretical Analysis ◽  
Shear Wave ◽  
Experimental Setup ◽  
Wave Velocities ◽  
Shear Wave Velocities
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