Loading...
Search for:
heterogeneous-media
0.006 seconds
Dynamic renormalization group analysis of propagation of elastic waves in two-dimensional heterogeneous media
, Article Physical Review B - Condensed Matter and Materials Physics ; Volume 77, Issue 1 , 2008 ; 10980121 (ISSN) ; Bahraminasab, A ; Sahimi, M ; Rahimi Tabar, M. R ; Sharif University of Technology
2008
Abstract
We study localization of elastic waves in two-dimensional heterogeneous solids with randomly distributed Lamé coefficients, as well as those with long-range correlations with a power-law correlation function. The Matin-Siggia-Rose method is used, and the one-loop renormalization group (RG) equations for the coupling constants are derived in the limit of long wavelengths. The various phases of the coupling constants space, which depend on the value ρ, the exponent that characterizes the power-law correlation function, are determined and described. Qualitatively different behaviors emerge for ρ<1 and ρ>1. The Gaussian fixed point (FP) is stable (unstable) for ρ<1 (ρ>1). For ρ<1, there is a...
Elastic Analysis of a Functionally Graded Solid with Quadratic Variation under Various Types of Loading
, M.Sc. Thesis Sharif University of Technology ; Eskandari, Morteza (Supervisor)
Abstract
In this study, elastic analysis of a functionally graded full-space with quadratic variations under various types of loading is addressed. The elastic responses of the medium are obtained in closed-form under various types of loading including point load, concentrated moment, distributed patch load of rectangular and circular shape, normal ring load, and concentrated torsion. The displacement fields are derived by virtue of the appropriate Green’s functions corresponding to the FGMs with a quadratic variation of elastic moduli and constant poisons ratio of = 0.25 .For the special case of homogeneous medium, the results are verified with available solutions. Furthermore, effects of degree of...
Numerical Simulation of Acoustics Wave Propagation in Bubbly Media, Using Lattice Boltzmann Method
, M.Sc. Thesis Sharif University of Technology ; Taeibi Rahni, Mohammad (Supervisor) ; Massah, Hamid Reza (Supervisor)
Abstract
The Phenomena of generation and propagation of pressure waves (e.g. sounds) are of fundamental importance in studying fluid dynamics. Conventional computational fluid dynamics (CFD) simulations has always been part of the investigation. On the other hand, the lattice Boltzmann method (LBM) has been developed into an alternative and promising numerical method for simulating sound propagation in heterogeneous media with complex geometries. In this project, propagation of sound waves in a liquid was simulated, using lattice Boltzmann method (LBM) and particularly phononic model. To survey effect of different viscosities on this phenomenon, the kinematic viscosity of the medium was varied and...
Percolation-based effective permeability estimation in real heterogeneous porous media
, Article 15th European Conference on the Mathematics of Oil Recovery, 29 August 2016 through 1 September 2016 ; 2016 ; 9462821933 (ISBN); 9789462821934 (ISBN) ; Gago, P ; King, P ; DCSE; Schlumberger; Shell ; Sharif University of Technology
European Association of Geoscientists and Engineers
Abstract
It has long been understood that flow behavior in heterogeneous porous media is largely controlled by the continuity of permeability contrasts. With this in mind, we are looking in new methods for a fast estimation of the effective permeability which concentrates on the properties of the percolating cluster. From percolation concepts we use a threshold permeability value (Kth) by which the gridblocks with the highest permeability values connect two opposite side of the system in the direction of the flow. Those methods can be applied to heterogeneous media of a range of permeabilities distribution and various underlying structures. We use power law relations and weighted power averages that...
Surface Growth in Non-Homogeneous Environments and the Elevated Noise
, M.Sc. Thesis Sharif University of Technology ; Moghimi-Araghi, Saman (Supervisor) ; Naji, Ali (Supervisor)
Abstract
Surface Growth processes, as critical phenomena, have long attracted physicists’ attention. In many cases, the surfaces exhibit scale-free properties and they become fractals. Based on the large scale dy- namics of each model, one can divide the different models into niversality classes. Two well-known universality classes are Edwards-Wilkinson and KPZ. the kind of noise present in the stochastic differ- ential equation describing the model, can determine the large-scale dynamics to a large extent. In this research, we have perturbed the Edwards-Wilkinson dynamics to make it suitable for describing growth processes in non-homogeneous environments, such that the noise gets stronger in higher...
Characterization of viscous fingering during displacements of low tension natural surfactant in fractured multi-layered heavy oil systems
, Article Chemical Engineering Research and Design ; Volume 96 , 2015 , Pages 23-34 ; 02638762 (ISSN) ; Shokrollahi, A ; Ghazanfari, M. H ; Rashtchian, D ; Sharif University of Technology
Institution of Chemical Engineers
2015
Abstract
Characterization of viscous fingering in low tension displacements especially for heavy oil surfactant pair in heterogeneous systems is neither straight forward nor well understood. In this work layered porous models containing fractures with different geometrical properties were used and the finger behavior during displacement of LTNS, as a new EOR agent, in heavy oil was quantified. Dynamic propagation of the fingers independent to the type of heterogeneity is well correlated with the dimensionless displacement time in a linearly form. And also, the rate of finger growth is nearly independent to the type of medium heterogeneity. When injection is scheduled through high permeable region in...
Nanofluid flooding in a randomized heterogeneous porous media and investigating the effect of capillary pressure and diffusion on oil recovery factor
, Article Journal of Molecular Liquids ; Volume 320 , December , 2020 ; Esfandeh, S ; Hosseinizadeh, E ; Sharif University of Technology
Elsevier B.V
2020
Abstract
In the initial recovery stage, only 5 to 15% of hydrocarbons can be extracted from oil reservoirs, so it is necessary to supply energy from an external reservoir or to use advanced solutions to increase oil recovery. By using secondary recovery method and flooding, greater amount of oil can be extracted. In this study, a new procedure of flooding using nanofluid was simulated. The nanofluid and source rock were modeled as a single phase and heterogeneous porous media, respectively. The geometry was considered as a two-dimensional rectangular area. Two phase Darcy equations and mass transfer equations were utilized to simulate this process. Moreover, the effects of different volume fractions...
Propagation and localization of acoustic and elastic waves in heterogeneous materials: Renormalization group analysis and numerical simulations
, Article Acta Mechanica ; Volume 205, Issue 1-4 , 2009 , Pages 197-222 ; 00015970 (ISSN) ; Rahimi Tabar, M. R ; Bahraminasab, A ; Sepehrinia, R ; Vaez Allaei, S. M ; Sharif University of Technology
2009
Abstract
We describe and discuss the recent progress in the study of propagation and localization of acoustic and elastic waves in heterogeneous media. The heterogeneity is represented by a spatial distribution of the local elastic moduli. Both randomly distributed elastic moduli as well as those with long-range correlations with a nondecaying power-law correlation function, are considered. The motivation for the study is twofold. One is that recent analysis of experimental data for the spatial distribution of the elastic moduli of rock indicated that the distribution is characterized by the type of long-range correlations that we consider in this study. The second motivation for the problem is to...