  An uncoupled multi-scale homogenization approach is used to estimate the
effective thermal conductivities of plain weave C/C composites with a high
degree of porosity. The geometrical complexity of the material system on
individual scales is taken into account through the construction of a suitable
representative volume element (RVE), a periodic unit cell, exploiting the
information provided by the image analysis of a real composite system on every
scale. Two different solution procedures are examined. The first one draws on
the classical first order homogenization technique assuming steady state
conditions and periodic distribution of the fluctuation part of the temperature
field. The second approach is concerned with the solution of a transient flow
problem. Although more complex, the latter approach allows for a detailed
simulation of heat transfer in the porous system. Effective thermal
conductivities of the laminate derived from both approaches through a
consistent homogenization on individual scales are then compared with those
obtained experimentally. A reasonably close agreement between individual
results then promotes the use of the proposed multi-scale computational
approach combined with the image analysis of real material systems.
