In pressure infiltration processing of metal-matrix composites, molten metal is injected under external pressure into a porous preform of the reinforcing phase and solidified, either during infiltration or after the mold is filled. If infiltration is isothermal, the physics of the process are similar to drainage phenomena encountered in soil mechanics. Using this similarity, a finite-element software is developed to simulate metal-matrix composite infiltration by adaptation of a code originally developed for soil mechanics. Solutions are given for isothermal infiltration of porous preforms by a molten metal under any increasing function of the applied pressure vs time, taking into account capillary phenomena. Experimental validation is performed using SAFFIL alumina fiber preforms infiltrated with an aluminum matrix in a series of isothermal infiltration experiments in unidirectional and axisymmetric configurations. Numerical and experimental data show good agreement, both in terms of infiltration kinetics and porosity distribution. The simulation tool can, thus, be applied for isothermal infiltration of complex geometries and boundary conditions and aid mold design and process parameter optimization.