Continuous gravity settlers are widely used for liquid liquid separations in solvent extraction processes. In the present work, the effects of settler design [geometry, settling area (A), locations of inlet and outlet] and internals (baffles, picket fence, end-plate) on the separation performance were investigated. An experimentally validated Eulerian CFD model implemented in OpenFOAM was used. For a fixed flow rate of dispersion (Q(t)), an increase in the settler length led to a reduction in the dispersion-band thickness. For settlers with length-to-width ratios (L/W) of <1.5, the settler performance was found to be improved by combined use of baffle and picket fence. The organic-to-aqueous phase ratio (a(org)/a(aq)), end-plate height, and aqueous outlet location were found to influence the phase separation significantly. An empirical correlation was developed to predict the dispersion-band thickness as a function of Q(t), A, rho(org)/rho(aq), inlet baffle opening slot position, and alpha(org)/alpha(aq). The present work will be useful for the design of optimal settler configurations.