A cell-automaton model for a binary eutectic system has been developed. This study examines a Bridgeman-type temperature field with periodic boundary conditions. A stable operating range of lamellar spacings is obtained based on the parameters of the temperature field. The undercooling of the liquid phase ahead of the solid/liquid interface is also estimated in the calculations. The estimated lamellar spacings and undercoolings agree well with the predictions of the Jackson-Hunt model.