Plain bearings are devices used in large equipment, for example in generator shafts of hydroelectric power plants. For this application, some type of lubricant oil is commonly used in order to reduce both friction and heating of the sliding parts. However, in such application, the lubricant oil film is exposed not only to high temperature caused by friction between sliding parts, but also to high tangential velocity due to the dimensions of the shaft. These factors contribute to the atomization and spraying effect of the lubricant oil in the bearing, generating a kind of vapor which is then projected onto the other parts of the equipment, and may cause failures in other systems and even accidents at work. The literature presents some attempts to solve the problem, but, up to now, none of them has achieved this goal. Thus, the present dissertation proposes, from numerical studies with the Finite Element Method, a sealing solution for the lubricant oil of these equipments, using a ferrofluid as a barrier to the passage of oil vapor. The literature review showed that the application of ferrofluid in bearings is vastly explored in precision equipment because it provides enough stiffness to the sealing material, in such a way it guarantees the seal and viscosity, thus reducing the friction between the parts. The finite element analysis, used as a tool, helps develop the design of the fence. Since ferrofluid will serve only as a barrier when exposed to a magnetic field, in general, the bearing assembly is just a concentrator of the magnetic field in the region of interest. Thus, the numerical simulation makes it possible to optimize the design, allowing the evaluation of several models of magnetic circuits, without the need to construct several prototypes. As results of the work, we have the finite element modeling of the bearing and its magnetic parts, and also the verification of the magnetic field density in the ferrofluid. Experimental validation of the numerical model is also presented. This is done by means of measurements of the magnetic field surrounding a prototype of the fence, showing that the numerical simulation and the proposed model are able to represent the actual model of the bearing.