scholarly journals Attenuation and dispersion of P-waves in porous rocks with planar fractures: Comparison of theory and numerical simulations

Geophysics ◽  
2006 ◽  
Vol 71 (3) ◽  
pp. N41-N45 ◽  
Author(s):  
Gracjan Lambert ◽  
Boris Gurevich ◽  
Miroslav Brajanovski
Keyword(s):  
Numerical Simulation ◽  
Wave Propagation ◽  
Theoretical Model ◽  
Random Distribution ◽  
Constant Thickness ◽  
Porous Rocks ◽  
P Waves ◽  
Periodic Distribution ◽  
Attenuation And Dispersion ◽  
Good Agreement

To explore the validity and limitations of the theoretical model of wave propagation in porous rocks with periodic distribution of planar fractures, we perform numerical simulation using a poroelastic reflectivity algorithm. The numerical results are found to be in good agreement with the analytical model, not only for periodic fractures, but also for random distribution of constant thickness fractures.

Further discussion on attenuation and dispersion of electromagnetic wave propagation in fluid‐saturated porous rocks and applications to dielectric‐constant well logging

Geophysics ◽  
1983 ◽  
Vol 48 (10) ◽  
pp. 1373-1380 ◽  
Author(s):  
H. Pascal
Keyword(s):  
Dielectric Constant ◽  
Wave Propagation ◽  
Electromagnetic Wave ◽  
Electromagnetic Wave Propagation ◽  
Phase Model ◽  
Phase System ◽  
Porous Rocks ◽  
Two Phase ◽  
Advantages And Disadvantages ◽  
Attenuation And Dispersion

This paper presents a more detailed analysis of some basic problems of electromagnetic wave propagation through a porous medium saturated with fluid, associated directly with quantitative interpretation of dielectric constant logging. The advantages and disadvantages of a new approach, in which fluid‐saturated porous rock is considered as a two‐phase system, are discussed and compared with those obtained from the single‐phase model. It is shown that the two‐phase model may provide a better interpretation of dielectric constant logging.

scholarly journals Numerical Simulation of 980 nm-LD-Pumped Yb3+-Er3+-Tm3+-Codoped Fiber Amplifier for 1500 nm and 1600 nm Bands

2009 ◽  
Vol 2009 ◽  
pp. 1-8
Author(s):  
Chun Jiang
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Pump Power ◽  
Fiber Length ◽  
Fiber Amplifier ◽  
Numerical Results ◽  
Experimental Result ◽  
Signal Wavelength ◽  
Gain Spectra ◽  
Good Agreement

The theoretical model of Yb3+-Er3+-Tm3+-codoped fiber amplifier pumped by 980 nm laser is proposed, and the rate and power propagation equations are numerically solved to analyze the dependences of the gains at 1500 nm and 1600 nm bands on the activator concentrations, fiber length, pump power, and signal wavelength. The numerical results show that our model is in good agreement with experimental result, and with pump power of 200 mW and fiber length varying from 0.15 to 1.5 m, the gains at the two bands may reach 10.0–20.0 dB when the codoping concentrations of Yb3+, Er3+, and Tm3+ are in the ranges 1.0–3.0×1025, 1.0–3.0×1024, and 1.0–3.0×1024 ions/m3, respectively. The fiber parameters may be optimized to flatten the gain spectra.

Numerical Simulation on the Effective Thermal Conductivity of Porous Material

2012 ◽  
Vol 557-559 ◽  
pp. 2388-2395
Author(s):  
Shan Qi Liu ◽  
Yong Bing Li ◽  
Xu Yao Liu ◽  
Bo Jing Zhu ◽  
Hui Quan Tian ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Porous Material ◽  
Effective Thermal Conductivity ◽  
Random Distribution ◽  
Simulation Method ◽  
Solid Skeleton ◽  
Material Models ◽  
Application Prospects ◽  
Good Agreement

The thermal conductivity of porous material is an important basic parameter, but it is not easy to study, due to the complexity of the structure of porous material. In the present work, we show a numerical simulation method to study the thermal conductivity of the porous material. We generate 200 material models with random distribution of solid skeleton and air for a fixed porosity, then we get the effective thermal conductivity of the porous material by Monte Carlo statistical analysis. The results are in good agreement with the previous empirical formula. The numerical results show that the effective thermal conductivity of porous material depends on the thermophysical properties of solid skeleton and air, the pore distribution and pore structure, the numerical error decreases with the increase in the number of grids, this finite element method can be used to estimate the effective thermal conductivity of composites and maybe has broad application prospects in terms of computing the effective thermal conductivity and other physical properties of composite material with known components.

scholarly journals Numerical Simulation of Propagation and Run-Up of Long Waves in U-Shaped Bays

Fluids ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 146
Author(s):  
S. R. Pudjaprasetya ◽  
Vania M. Risriani ◽  
Iryanto
Keyword(s):  
Numerical Simulation ◽  
Wave Propagation ◽  
Long Waves ◽  
Staggered Grid ◽  
Wave Focusing ◽  
Consistent Approximation ◽  
Saint Venant Equations ◽  
Wave Shoaling ◽  
Run Up ◽  
Good Agreement

Wave propagation and run-up in U-shaped channel bays are studied here in the framework of the quasi-1D Saint-Venant equations. Our approach is numerical, using the momentum conserving staggered-grid (MCS) scheme, as a consistent approximation of the Saint-Venant equations. We carried out simulations regarding wave focusing and run-ups in U-shaped bays. We obtained good agreement with the existing analytical results on several aspects: the moving shoreline, wave shoaling, and run-up heights. Our findings also confirm that the run-up height is significantly higher in the parabolic bay than on a plane beach. This assessment shows the merit of the MCS scheme in describing wave focusing and run-up in U-shaped bays. Moreover, the MCS scheme is also efficient because it is based on the quasi-1D Saint-Venant equations.

On White’s model of attenuation in rocks with partial gas saturation

Geophysics ◽  
1979 ◽  
Vol 44 (11) ◽  
pp. 1806-1812 ◽  
Author(s):  
N. C. Dutta ◽  
A. J. Seriff
Keyword(s):  
Seismic Waves ◽  
Numerical Calculations ◽  
Porous Solids ◽  
Approximate Theory ◽  
Porous Rocks ◽  
Low Frequencies ◽  
Exact Calculations ◽  
Attenuation And Dispersion ◽  
Gas Compressibility ◽  
Good Agreement

In two important papers, J. E. White and coauthors (White, 1975; White et al, 1976) have given an approximate theory for the calculation of attenuation and dispersion of compressional seismic waves in porous rocks filled mostly with brine but containing gas‐filled regions. Modifications of White’s formulas for [Formula: see text] and Q in the case of gas‐filled spheres brings the results into good agreement with the more exact calculations of Dutta and Odé (1979a, b, this issue), who used Biot’s theory for porous solids. In particular, the modified formulas give the expected Gassmann‐Wood velocity at very low frequencies. Inclusion of the finite gas compressibility in numerical calculations for gas‐filled spheres shows an interesting maximum of the attenuation at low gas saturations which is not seen if the gas is ignored. A comparison of the attenuation calculated for the same rock and fluids but for three different geometries of the gas‐filled regions suggests that the configuration of the gas‐filled zones does not have an important effect on the magnitude of the attenuation.

scholarly journals Numerical simulation of shock wave propagation in 2-D channels with obstacles filled with chemically reacting gas suspensions

2019 ◽  
Vol 23 (Suppl. 2) ◽  
pp. 623-630 ◽  
Author(s):  
Yulia Kratova ◽  
Alexander Kashkovsky ◽  
Anton Shershnev
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Wave Propagation ◽  
Shock Wave Propagation ◽  
Test Case ◽  
Test Cases ◽  
Fortran Code ◽  
Speed Up ◽  
Chemically Reacting ◽  
Good Agreement

Modification of the serial Fortran code for solving unsteady 2-D Euler equations for the mixture of compressible gas and polydisperse particles was carried out using OpenMP technology. Modified code was verified and parallel speed-up was measured. Analysis showed that the data on parallel efficiency is in a good agreement with the Amdahls law, which gives the estimate for serial code fraction about 30%. Parallel code was used for the numerical simulation of two test-cases, namely shock wave propagation in 2-D channel with obstacles filled with reactive Al-O2 gas particle mixture and heterogeneous detonation propagation in polydisperse suspensions. For the first test-case the data on particles distribution in the flow was obtained, the existense of particle free zones inside the vortices was demonstrated and the attenuation of a shock wave was studied. In the second test, numerical simulation of detonation shock wave propagation in plain 2-D channel for the three polydisperse mixtures was carried out and data on detonation regimes was also obtained.

Modeling of mass transfer in biofilms in oscillatory flow conditions using k-ɛ turbulence model

2003 ◽  
Vol 3 (1-2) ◽  
pp. 201-207
Author(s):  
H. Nagaoka ◽  
T. Nakano ◽  
D. Akimoto
Keyword(s):  
Numerical Simulation ◽  
Mass Transfer ◽  
Turbulence Model ◽  
Uptake Rate ◽  
Oscillatory Flow ◽  
Substrate Uptake ◽  
Flow Conditions ◽  
Mass Transfer Mechanism ◽  
Substrate Uptake Rate ◽  
Good Agreement

The objective of this research is to investigate mass transfer mechanism in biofilms under oscillatory flow conditions. Numerical simulation of turbulence near a biofilm was conducted using the low Reynold’s number k-ɛ turbulence model. Substrate transfer in biofilms under oscillatory flow conditions was assumed to be carried out by turbulent diffusion caused by fluid movement and substrate concentration profile in biofilm was calculated. An experiment was carried out to measure velocity profile near a biofilm under oscillatory flow conditions and the influence of the turbulence on substrate uptake rate by the biofilm was also measured. Measured turbulence was in good agreement with the calculated one and the influence of the turbulence on the substrate uptake rate was well explained by the simulation.

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