Dukhin number
= Dukhin number
{c}
{title2=$\mathrm{Du}$}
A dimensionless ratio comparing surface conduction with bulk conduction over a characteristic length. With pore radius r and surface conductance $K_s$, one convention is $\mathrm{Du}=K_s/(\sigma r)$; the cylindrical surface-to-bulk conductance ratio is twice this value.