The fluid structure interaction for an aerostatic bearing and a substrate is solved numerically by a semi-analytical model, programmed in the software package MATLAB. This semi-analytical model uses a fluidic network of resistances and capacities to solve the pressure field in the bearing channel. These pressures are sent to a mechanical module, which computes the substrate deformations by the direct stiffness method. This semi-analytical model is verified by a second model, built into the commercial software package ANSYS. The ANSYS model includes a two-way coupled FEM and FVM solver. Position and time-dependent bearing height variations are computed by means of a dynamic mesh. The implementation of the semi-analytical model is done and verified by three cases. The first case verifies the pressure profile inside a parallel plate configuration with a moving top wall. The last two cases verify the time-dependent position of a rigid and flexible substrate supported by an aerostatic bearing. The semianalytical model is proved to be an effective tool for aerostatic bearing design, since it is able to solve the FSI within a couple of minutes instead of days for a coupled FEM and FVM solver