In this talk we are going to present a technique of deformation of Riemannian metrics that allows us to modify the behavior of a geodesic flow. In particular we are going to show how to construct partially hyperbolic geodesic flows that are not of Anosov type. Geodesic flows are particular examples of a more general class of flows called "contact flows", so we are going to present a few very preliminary results about the general setting of partially hyperbolic contact flows.