Two stable POD-based approximations to the Navier–Stokes equations

Abstract.The governing equations of viscous flows, the Navier–Stokes equations, are approximated by means of a low order model based on proper orthogonal decomposition (POD). Numerical evidence and analysis of simplified models show that the resulting time-wise semidiscretization is only marginally stable. Here, two methods providing additional stabilization are described: the first is based on a Lax–Wendroff type artificial diffusion term, while the second is a reinterpretation of POD in the frame of the finite element functional least square method.