The performance of aquatic locomotion is closely related to the circulation of the flow around the animal's body and primarily to the intensity of the induced flow downstream of the tail and its characteristics. This developing wake consists in a Von Karman street vortices whose vortices are periodically emitted with each flap of the tail. The way the tail moves in the fluid (angle of attack, amplitude, frequency ...) determines the swimming performance. Animals can adjust their swimming kinematics to optimize their performance. Different criteria can define performance, such as energy efficiency, maximum speed (prey-predator system), or even stealth. The shape of the body and the tribological properties of the skin, which influence the propulsion and drag produced by swimming animals, must be taken into account. The central objective of this thesis is to contribute to the development of a numerical model based on real data such as geometry, kinematics, skin texture (data-driven numerical modeling) in order to simulate the complex phenomena of unsteady fluid-structure interaction (FSI), involved in anguilliform swimming within an incompressible viscous flow in the presence of a free surface.The aim is to identify the hydrodynamic mechanisms that will allow us to obtain estimates of the efficiency of this swimming in terms of propulsive force and energy efficiency, based on the kinematic and velocimetric data that characterize the swimming of snakes. This thesis work is part of a larger ANR (Dragon II) project in which biologists, fluid mechanics, mathematicians and roboticists are involved. A strong link will be maintained with the experimentalists of the project and experimental data on the swimming of real snakes and bio-inspired robots will be made available in order to validate the numerical model. The candidate will be required to participate in measurement campaigns at the Ecole Supérieure de Physique et de Chimie Industrielles in Paris, at the PPRIME Institute in Poitiers and at the Center for Biological Studies in Chizé .
BIOMIMETISM AND BIOINSPIRATION OF THE ANGUILLIFORM SWIM OF A SNAKE
The proposed studies will relate to a low Reynolds laminar flow of a two-dimensional mixture layer of a highly viscous dielectric fluid. The fluid / fluid interface will be studied experimentally under different conditions. This subject is part of action 5.1 of the INTERACTIVES labex, action which concerns the manipulation of internal flow by electrical discharge and charge injection.
We propose to numerically derive closed-loop control strategies of different flows. We will treat the numerical simulation aspects of physical mechanisms (electrodynamics and fluid mechanics) and the development of innovative control strategies (Data Driven approaches based on machine learning methods).
We will study two rather emblematic types of flows:
- The flow behind an obstacle (cylinder, wing profile, backward facing step). This type of strongly separated flow is particularly interesting in cases where the objective of the control is to increase aircraft stealth.