A computer-simulation model is introduced to study the transport properties of a binary fluid mixture in which the constituents of one fluid (the tracer particles) carry charges in a linear charge-density gradient in the background charge of the second fluid. In the steady-state equilibrium, an effective conductivity ${\mathrm{\sigma }}_{\mathit{c}}$(p,r) is estimated as a function of the carrier concentration p and the range of interactions r. The conductivity is observed to vary nonmonotonically with the concentration p, and it exhibits a maximum at a characteristic value ${\mathit{p}}_{\mathit{c}}$. The conductivity decreases when the range of interaction is increased until a characteristic value ${\mathit{r}}_{\mathit{c}}$, beyond which (r>${\mathit{r}}_{\mathit{c}}$) it begins to saturate as the onset of screening spans with r-${\mathit{r}}_{\mathit{c}}$.

• Received 5 February 1990

DOI:https://doi.org/10.1103/PhysRevA.42.3363