NUMERICAL-CALCULATIONS OF THE THERMAL-CONDUCTIVITIES OF COMPOSITES - A 3-D MODEL

A 3-D numerical finite-difference model to calculate the thermal condu ctivity of a composite with Two or more constituents has been develope d to better understand how the relative quantities and distributions o f the component materials within a sample affect the whole sample cond uctivity. It is found that different distributions of similar componen ts within a sample can yield whole sample conductivity differences gre ater than a factor of 2. Comparisons are made between the numerical mo del results and the geometric and real-space renormalization group the ory (RSRG) models and the effective medium approximation (EMA) for ran dom distributions. Although good agreement exists between the numerica l model and the EMA for the ranges of constituent conductivities consi dered, the geometric and RSRG models give lower values.