Mardi 2 décembre 2025 à 11h00, salle des séminaires IRPHE
Abstract: Internal waves (IWs) are ubiquitous in stratified media such as the Earth’s oceans and atmosphere. They play a key-role in the energy budget of our oceans. One of the ways in which these waves are generated is through interaction with topography. Motivated by the goal of understanding the physics of scattering, generation and possible energy extraction by viscous IWs in a stratified fluid, we look at Boundary Integral Equation approaches that can be used with arbitrary geometries. These require an appropriate Green’s function. The inviscid Green’s function of IWs is well known, for example using the Hurley analytical continuation procedure, but the viscous case is less well understood. We examine its properties asymptotically and numerically, focusing on the case of small viscosity (appropriately nondimensionalized). This approach can be extended to other viscous flow systems, including anisotropic Brinkman flow and internal waves incorporating density diffusion. We then employ techniques which take advantage of the Green’s function’s singularity structure to numerically solve the boundary integral equations.
We will also look at fluid-fluid interactions, specifically the theoretical modeling of intrusion of a secondary fluid into a stratified ambient at a neutrally buoyant level. This penetration of secondary fluid generates IWs in the ambient; through a feedback mechanism, these waves affect the self-similar profiles of height and velocity of the intrusion, when compared with a homogeneous ambient.
Saikumar Bheemarasetty University of California, San Diego