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Effective diffusion in 2D. Effective diffusivities for ellipses with χ = 1, 1/2, and 1/5 obtained by homogenization method are plotted as a function of area density A and compared to fα,ϕc(ϕ(A))=(1−ϕ(A)∕ϕc)αϕc (solid curves) and gα(ϕ(A)) = (1 − ϕ(A))α = e−αA (dashed curves) with the corresponding values of α and ϕc from Table 4. The number of obstacles used in the computations is n = 40 000. Error bars are comparable to the symbol sizes.
