NUMERICAL COMPUTATIONS OF CONDUCTIVITY IN CONTINUUM PERCOLATION FOR OVERLAPPING SPHEROIDS

2010 ◽  
Vol 21 (06) ◽  
pp. 709-729 ◽  
Author(s):  
SHIGEKI MATSUTANI ◽  
YOSHIYUKI SHIMOSAKO ◽  
YUNHONG WANG

By numerically solving the generalized Laplace equations by means of the finite difference method, we investigated isotropic electric conductivity of a three-dimensional continuum percolation model consisting of overlapped spheroids of revolution in continuum. Since the computational results strongly depend upon parameters in the discretization methods of the finite difference method, we explored the dependences in details to construct the computational scheme which can represent the continuum percolation model well. Using the discrete scheme, we obtained the conductivity curves, σ =c (p -pc)t, depending upon aspect ratio of the conductive spheroids for the volume fraction p. We found the fact that the critical exponent t is not universal, which depends upon the shape of spheroids with a range varying from 1.58 ± 0.08 to 1.94 ± 0.18 whereas 1.85 is reported as the standard one of cubic lattice case [A. B. Harris, Phys. Rev. B28, 2614 (1983)]. We also discussed its relation to the nonuniversality in the broad distribution continuum percolation models.

2011 ◽  
Vol 243-249 ◽  
pp. 2638-2642
Author(s):  
Xu Dong Cheng ◽  
Wen Shan Peng ◽  
Lei Liu

This paper adopts the Finite-difference method to research the distribution of ground additional stress and distortion in differently isotropic and non-isotropic foundation conditions, and uses the Finite-difference method to compare with the Finite-element method and the three-dimensional settlement method used by the code. Through comparative analysis, the reliability and superiority of Finite-difference method used for calculating ground additional stress and settlement are justified.


Author(s):  
M.A. Mansour ◽  
M.A. Bakeir ◽  
A. Chamkha

Purpose – The purpose of this paper is to investigate natural convection fluid flow and heat transfer inside C-shaped enclosures filled with Cu-Water nanofluid numerically using the finite difference method. Design/methodology/approach – In this investigation, the finite difference method is employed to solve the governing equations with the boundary conditions. Central difference quotients were used to approximate the second derivatives in both the X and Y directions. Then, the obtained discretized equations are solved using a Gauss-Seidel iteration technique. Findings – It was found from the obtained results that the mean Nusselt number increased with increase in Rayleigh number and volume fraction of Cu nanoparticles regardless aspect ratio of the enclosure. Moreover the obtained results showed that the rate of heat transfer increased with decreasing the aspect ratio of the cavity. Also, it was found that the rate of heat transfer increased with increase in nanoparticles volume fraction. Also at low Rayleigh numbers, the effect of Cu nanoparticles on enhancement of heat transfer for narrow enclosures was more than that for wide enclosures. Originality/value – This paper is relatively original for considering C-shaped cavity with nanofluids.


1986 ◽  
Vol 108 (1) ◽  
pp. 6-11 ◽  
Author(s):  
Shou-Rue Chen ◽  
Samuel S. Lee ◽  
Yuan Mao Huang

A three-dimensional mathematical model has been developed to simulate the flow condition in a scroll. Coordinate transformations are used as an effective tool to make the model universal, and the final governing equations are solved by the finite difference method. Three cases of scroll geometry have been investigated and the results are compared with one another to show the effects of scroll geometry on the flow condition at the outlet of the scroll.


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