It's done all the time. The other answers are tending towards behavior but computer models are made everyday for physical problems. Computer graphic parts for an aircraft are referred to as models. The are virtual copies of the real world. Computer models are created to simulate air flow for aerodynamic studies before real life models are placed in a wind tunnel. Mechanisms such as landing gear showing relative movement of all components are produced. In the non-aerospace world, heat and mass simulations are produced for fluid flow in heat producing operations such as nuclear reactor cooling equipment. Fluid flow through electricity producing turbines are among the other uses of models.