INFLUENCE OF WAVES ON LAGRANGIAN ACCELERATION IN TWO-DIMENSIONAL TURBULENT FLOWS ∗, ∗∗, ∗∗∗

Abstract. The Lagrangian statistics in rotating Saint-Venant turbulence are studied by means of direct numerical simulation using a pseudo-spectral discretization fully resolving, both in time and space, all the inertio-gravity waves present in the system. To understand the influence of waves, three initial conditions are considered, one which is dominated by waves, one which is dominated by vortices, and one which is intermediate between these two extreme cases. It is found that Lagrangian acceleration is strongly influenced by the presence of waves, as are the Lagrangian velocity increments, for incremements that are sufficiently short, and that vortex motion influences mostly the component of Lagrangian acceleration which is perpendicular to the local velocity. 1