A numerical simulation model for the convective mass transport occurring during the liquid phase epitaxial growth of GaInAs is presented. The mass transport and fluid flow equations in the liquid phase, mass transport equation in the solid phase and the relationships between concentrations and temperature obtained from the phase diagram constitute the governing equations. These equations together with appropriate interface and boundary conditions were solved numerically by the finite element method for a sandwich growth system. Numerical results show that the solutal convection plays an important role in this materials processing technique, enhances growth rate and influences compositional uniformity of the grown crystals.