scholarly journals Fast Fourier Transformation method for computing the permeability of periodic porous media

2017 ◽  
Vol 39 (2) ◽  
pp. 121-133
Author(s):  
Nguyen Trung Kien ◽  
Nguyen Duy Hung

A Fourier-based method is adopted to determine the permeability of periodic porous media made up of a rigid skeleton saturated by viscous fluid. The flow, induced by a prescribed macroscopic gradient of pressure, adopts the Stokes equations with incorporating a condition of adherence at the surface of the solid. The permeability is determined by solving a linear problem on a unit cell for which we determine the local velocity fields due to a prescribed gradient of pressure. The method uses the Fourier Transformation and exact expressions of the periodic Green tensor in the Fourier space. It is shown that the resolution of the problem requires an introducing of undetermined forces acting within the solid phase.

2015 ◽  
Vol 37 (3) ◽  
pp. 169-176
Author(s):  
Nguyen Van Luat ◽  
Nguyen Trung Kien

Article introduces the Fast-Fourier transformation method (FFT) and an approximation method to calculate the conductivity of compound-inclusion composites in two-dimensional space. The approximation compares favorably with the numerical results for a number of periodic and random models over a range of volume proportions of phases, but divers at large volume proportions of the included phases when the interactions between the inclusions are more pronounced.


1995 ◽  
Vol 2 (3) ◽  
pp. 205-218 ◽  
Author(s):  
T. Ge ◽  
A. Y. T. Leung

A semianalytical algorithm is proposed for the solutions and their stability of a piecewise nonlinear system. The conventional harmonic balance method is modified by the introduction of Toeplitz Jacobian matrices (TJM) and by the alternative applications of fast Fourier transformation (FFT) and its inverse. The TJM/FFT method substantially reduces the amount of computation and circumvents the necessary numerical differentiation for the Jacobian. An arc-length algorithm and a branch switching procedure are incorporated so that the secondary branches can be independently traced. Oscillators with piecewise nonlinear characteristics are taken as illustrative examples. Flip, fold, and Hopf bifurcations are of interest.


2015 ◽  
Vol 23 (3) ◽  
pp. 3341
Author(s):  
Raoul-Amadeus Lorbeer ◽  
Heiko Meyer ◽  
Tammo Ripken

2012 ◽  
Vol 9 (1) ◽  
pp. 65-68
Author(s):  
R.N. Gafiyatov

The mathematical model of two-fractional mixture of liquid with vapor-gas bubbles of different gases and sizes with phase transformations is presented. The dispersive equation is received, dispersive curves that determine the propagation of acoustic disturbances was plotted. Calculations on the propagation of impulse pressure perturbations were performed by means of a fast Fourier transformation method.


2009 ◽  
Vol 25 (09) ◽  
pp. 1835-1840
Author(s):  
ZHAO Jian-Wei ◽  
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WANG Fen-Ying ◽  
JIANG Lu-Yun ◽  
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