Dictionary:Cole-Cole relaxation model
(kōl kōl) A model for induced polarization (IP) effects in which the effective impedance varies as a power of the frequency. The complex resistivity ρ(ω) is given by
where Ro is the dc resistivity, τ is the time constant, and c is the frequency dependence. Typical ranges for parameters are m=0.1 to 1.0, depending on the mineral content, τ=10–4 to 104 depending on grain size, and c=0.2 to 0.6 depending on the particle size distribution. Compare Warburg impedance, for which the value of c is 0.5.